Draft California 2026 Integrated Report (303(d) List/305(b) Report)

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): Dissolved oxygen concentrations for waters not listed in Table 3-1, and where dissolved oxygen objectives are not prescribed, shall not be reduced below 7.0 mg/L for waters designated as SPWN.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One sample was collected from the Larabee Creek station (111PS0013).

Temporal Representation:

One sample was collected in August 2008.

Environmental Conditions:

QAPP Information:

SWAMP QAPP

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 155284, Oxygen, Dissolved	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318840

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Aquatic Life Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed dissolved oxygen data for Adventure Scientists (Volunteer)* and determined that 0 of 0 samples are less than the July-October minimum of 6.0 mg/L and 1 of 1 sample is less than the November-June minimum of 9.0 mg/L, so that 1 of 1 sample exceeds the water quality objective.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Basin, Chapter III, General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states: Dissolved oxygen concentrations shall conform to those limits listed in Section 3.3.5. Section 3.3.5 lists dissolved oxygen concentration limits for COLD beneficial use waters to be a daily minimum of 6.0 mg/L and a 7-day moving minimum average of 8.0 mg/L and dissolved oxygen concentration limits for SPWN beneficial use waters to be a daily minimum of 9.0 mg/L and a 7-day moving average of 11.0 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

This sample was collected at sampling station: Eel Wild and Scenic River-40.64.124.28; station code: ADVENTURESCIENTISTS-40.64.124.28.

Temporal Representation:

This sample was collected on 6/25/2021.

Environmental Conditions:

QAPP Information:

QAPP for Adventure Scientists (Volunteer)*

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 155284, Oxygen, Dissolved	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318767

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Aquatic Life Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed dissolved oxygen data for EPA National Aquatic Resources Survey (NARS) and determined that 0 of 2 samples are less than the July-October minimum of 6.0 mg/L and 0 of 0 samples are less than the November-June minimum of 9.0 mg/L, so that 0 of 2 samples exceed the water quality objective.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

These samples were collected at sampling station name: Eel River; station code: NARS_WQX-CARM-1012.

Temporal Representation:

These samples were collected from 8/18/2014-8/19/2014.

Environmental Conditions:

QAPP Information:

QAPP for EPA National Aquatic Resources Survey (NARS)

QAPP Information Reference(s):

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

Line of Evidence (LOE) for Decision ID 155284, Oxygen, Dissolved	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318241

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Aquatic Life Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed dissolved oxygen data for SWAMP Perennial Stream Surveys and determined that 0 of 0 samples exceed the July-October minimum of 6.0 mg/L and 1 of 1 sample exceeds the November-June minimum of 9.0 mg/L, so that 1 of 1 sample exceeds the water quality objective.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

This sample was collected from sampling station name: Larabee Creek ~0.5mi above Frost Creek; station code: 111PS0322.

Temporal Representation:

This sample was collected on 6/20/2017.

Environmental Conditions:

QAPP Information:

QAPP for SWAMP Perennial Stream Surveys

QAPP Information Reference(s):

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

Line of Evidence (LOE) for Decision ID 155284, Oxygen, Dissolved	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318028

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Aquatic Life Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assess data for parent project SWAMP Stream Pollution Trends and determined that 0 of 4 samples exceeded the July-October daily minimum of 6.0 mg/L and 0 of 0 samples exceeded the November-June daily minimum of 9 mg/L, so that 0 of 4 samples exceed the water quality objective for dissolved oxygen.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

These samples were collected at sampling station name: Eel River at Fernbridge; station code: 111EELFRN

Temporal Representation:

These samples were collected from 9/23/2013-9/15/2022

Environmental Conditions:

QAPP Information:

QAPP for SWAMP Stream Pollution Trends

QAPP Information Reference(s):

WQX from the NWQMP for the 2026 Integrated Report in Region 1

Line of Evidence (LOE) for Decision ID 155284, Oxygen, Dissolved	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318828

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Aquatic Life Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed dissolved oxygen data for Adventure Scientists (Volunteer)* and determined that 0 of 0 samples are less than the July-October minimum of 6.0 mg/L and 0 of 1 sample is less than the November-June minimum of 9.0 mg/L, so that 0 of 1 sample exceeds the water quality objective.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

This sample was collected at sampling station name: Eel Wild and Scenic River-40.45.123.99; station code: ADVENTURESCIENTISTS-40.45.123.99.

Temporal Representation:

This sample was collected on 6/4/2021.

Environmental Conditions:

QAPP Information:

QAPP for Adventure Scientists (Volunteer)*

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 155284, Oxygen, Dissolved	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318832

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Aquatic Life Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

This sample was collected at sampling station name: Eel Wild and Scenic River-40.47.124.11; station code: ADVENTURESCIENTISTS-40.47.124.11.

Temporal Representation:

This sample was collected on 6/24/2021.

Environmental Conditions:

QAPP Information:

QAPP for Adventure Scientists (Volunteer)*

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 155284, Oxygen, Dissolved	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

129864

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total Dissolved

Beneficial Use:

Cold Freshwater Habitat

Aquatic Life Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Twenty-four of the 34 minimum dissolved oxygen (DO) values calculated from samples collected in the Eel River Delta exceed the objectives. Samples were collected by the Wiyot Tribe and data are summarized by the Tribe (Wiyot 2007). This LOE is a copy of LOE 46837 from the 2012 Integrated Report. The data was reassessed based on new minimum thresholds for DO.

Data Reference:

Data for Dissolved Oxygen in McNulty Slough, December 2004 to December 2006. Table Bluff Reservation - Wiyot Tribe

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Basin, Chapter III, General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states: Dissolved oxygen concentrations shall conform to those limits listed in Section 3.3.5. Section 3.3.5 lists dissolved oxygen concentration limits for SPAWN beneficial use waters to be a daily minimum of 9.0 mg/L and a 7-day moving average of 11.0 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids. Implications for California's North Coast TMDLs. California Regional Water Quality Control Board, North Coast Region

Spatial Representation:

The samples were collected by the Wiyot Tribe at McNulty Slough. The site is on the seaward side of the tide gate located just south of McNulty Lane, adjacent to the old Wiyot Rancheria.

Temporal Representation:

The samples were collected every two weeks from December 2004 to December 2006. Samples were collected during mid and high tides. The sonde was deployed for approximately 15 minutes, with a 3-5 minute equilibration period and an 8-10 minute sample period with 4 second intervals. The minimum dissolved oxygen sample collected during the 8-10 minute sample period was used to determine exceedance of the objective.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Samples were collected according to Wiyot Tribe's "Draft Quality Assurance Program Plan (QAPP) for Water Quality Assessment and Monitoring" (McKernan et al. 2004).

QAPP Information Reference(s):

Draft Quality Assurance Program Plan (QAPP) for Water Quality Assessment and Monitoring. Table Bluff Reservation - Wiyot Tribe. Tribal Environmental Department. Prepared by Yurok Tribe Environmental Program. September 2004

Line of Evidence (LOE) for Decision ID 155284, Oxygen, Dissolved	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

101332

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

If DO concentrations fall below the numeric objectives set forth by the Basin Plan (2018). If NO, then the waterbody is supporting that beneficial use, if YES, then that waterbody is considered impaired.

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2018): Dissolved oxygen (DO) concentrations shall conform to the numeric objectives expressed in section 3.3.5.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

EVIDENCE OF SALMONID PRESENCE & LIFE CYCLE USE: Coho, steelhead and Chinook are present in the Lower Eel River HA (USEPA 2007). Rearing occurs year round and spawning/ incubation/ emergence occurs from November to June (Busby et al. 1996; CDFG 2004; Myers et al. 1998). Non-core rearing occurs in the mainstem Eel River, while core rearing occurs in tributaries.

Guideline Reference:

Status Review of Chinook Salmon from Washington, Idaho, Oregon, and California.

Guideline Reference:

Status Review of West Coast Steelhead from Washington, Idaho, Oregon, and California

Guideline Reference:

Recovery Strategy for California Coho Salmon: Report to the California Fish and Game Commission

Spatial Representation:

Information pertains to the Eel River HU, Lower Eel River HA (includes the Eel River Delta).

Temporal Representation:

Data are reflective of current conditions in this water body.

Environmental Conditions:

QAPP Information:

Information is considered to be of adequate quality for the Integrated Report process.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 155284, Oxygen, Dissolved	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318836

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Aquatic Life Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed dissolved oxygen data for QAPP for Adventure Scientists (Volunteer)* and determined that 0 of 0 samples are less than the July-October minimum of 6.0 mg/L and 1 of 1 sample is less than the November-June minimum of 9.0 mg/L, so that 1 of 1 sample exceeds the water quality objective.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

This sample was collected at sampling station name: Eel Wild and Scenic River-40.58.124.15; station code: ADVENTURESCIENTISTS-40.58.124.15.

Temporal Representation:

This sample was collected on 6/24/2021.

Environmental Conditions:

QAPP Information:

QAPP for Adventure Scientists (Volunteer)*

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 155284, Oxygen, Dissolved	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

129865

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

One of the one minimum dissolved oxygen (DO) values calculated from samples collected in the Eel River Delta exceed the objectives. This LOE is a copy of LOE ID 33875 from the 2012 Integrated Report. The data was reassessed based on new minimum thresholds for DO.

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One sample was collected from the Larabee Creek station (111PS0013).

Temporal Representation:

One sample was collected in August 2008.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

SWAMP QAPP

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 155284, Oxygen, Dissolved	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

46837

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Thirty-seven of the 52 minimum dissolved oxygen (DO) values calculated from samples collected in the Eel River Delta exceed the objectives. Data were divided into two categories, 1) no spawning and incubation occurring and 2) spawning and incubation occurring. Information on the timing of spawning and incubation for the Eel River was not readily available and thus information from the neighboring Russian River Watershed was used to determine periodicity (Steiner 1996). The minimum DO values when no spawning and incubation were occurring range from 2.71 mg/L to 11.85 mg/L (16 exceedences of the objective). Minimum DO values during times of spawning and incubation range from 4.77 mg/L to 10.39 mg/L (21 exceedences of the objective). Samples were collected by the Wiyot Tribe and data are summarized by the Tribe (Wiyot 2007). This LOE is a copy of LOE 23454 from the 2010 Integrated Report. The only edit made to the original LOE was to change the pollutant fraction from "Dissolved" to "Total Dissolved".

Data Reference:

Data for Dissolved Oxygen in McNulty Slough, December 2004 to December 2006. Table Bluff Reservation - Wiyot Tribe

A History of the Salmonid Decline in the Russian River.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Per the Basin Plan (NCRWQCB 2007): For waters not listed in Table 3-1 and where dissolved oxygen objectives are not prescribed the dissolved oxygen concentrations shall not be reduced below 7.0 mg/l for waters designated with the SPWN beneficial use, and shall not be reduced below 9.0 mg/l for waters
designated with the SPWN beneficial use during critical spawning and egg incubation periods.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - North Coast Region (Region 1)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected by the Wiyot Tribe at McNulty Slough. The site is on the seaward side of the tide gate located just south of McNulty Lane, adjacent to the old Wiyot Rancheria.

Temporal Representation:

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Samples were collected according to Wiyot Tribe¿s ¿Draft Quality Assurance Program Plan (QAPP) for Water Quality Assessment and Monitoring¿ (McKernan et al. 2004).

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 155284, Oxygen, Dissolved	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

129863

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Seven of the 17 daily minimum dissolved oxygen (DO) values calculated from samples collected in the Eel River Delta exceed the objectives. Samples were collected by the Wiyot Tribe and data are summarized by the Tribe (Wiyot 2007). This LOE is a copy of LOE 46837 from the 2012 Integrated Report. The data was reassessed based on new minimum thresholds for DO.

Data Reference:

Data for Dissolved Oxygen in McNulty Slough, December 2004 to December 2006. Table Bluff Reservation - Wiyot Tribe

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected by the Wiyot Tribe at McNulty Slough. The site is on the seaward side of the tide gate located just south of McNulty Lane, adjacent to the old Wiyot Rancheria.

Temporal Representation:

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Samples were collected according to Wiyot Tribe's "Draft Quality Assurance Program Plan (QAPP) for Water Quality Assessment and Monitoring" (McKernan et al. 2004).

QAPP Information Reference(s):


DECISION ID	155286	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Temperature, water
Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)(2018)
Revision Status	Revised
Sources:	Erosion/Siltation \| Flow Alteration/Regulation/Modification \| Removal of Riparian Vegetation
TMDL Name:	Eel River, Lower Mainstem Sediment & Temperature TMDLs
TMDL Project Code:	1206
Date TMDL Approved by USEPA:	12/18/2007
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal on the CWA section 303(d) List under sections 2.2 and SECTION of the Listing Policy. Under 4.2 of the Policy, a minimum of one line of evidence is needed to assess listing status. Thirteen lines of evidence are available in the administrative record to assess this pollutant. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the CWA section 303(d) List. There is sufficient justification to place it in the Being Addressed portion of the CWA 303(d) List because a TMDL has been completed and approved by RWQCB and USEPA, and is expected to result in attainment of the standard. DO NOT LIST For MCNULTY SLOUGH, there is one line of evidence (LOE 318906) and 1 of 45 samples exceed the objective, which does not exceed the allowable frequency in Table 3.2 of the Listing Policy. DO NOT DELIST For EEL RIVER, there are ten lines of evidence (LOEs 3661, 46504, 46793, 31520, 318031, 318770, 318831, 318835, 318839, 318843). Four of 66 samples exceed the objective and there is evidence that water temperatures do not reflect natural conditions, which impairs aquatic organisms. For LARABEE CREEK, there are two lines of evidence (LOEs 43802, 318244) and 0 of 2 samples exceed the objective, which is insufficient data to apply Table 4.2 of the Listing Policy. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. For Eel River, water temperatures impair aquatic organisms and this exceeds the evaluation guideline. 4. The "Lower Eel River TMDLs for Temperature and Sediment" were approved by the USEPA on December 30, 2002 and thus, this water body-pollutant combination is being addressed with a USEPA TMDL. 5. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. This listing does not apply to McNulty Slough, which lies within the Eel River HU, Lower Eel River HA (includes the Eel River Delta) water body. This listing does not apply to McNulty Slough, which lies within the Eel River HU, Lower Eel River HA (includes the Eel River Delta) water body.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be removed from the section 303(d) list because applicable water quality standards for the pollutant are being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:	This listing does not apply to McNulty Slough, which lies within the Eel River HU, Lower Eel River HA (includes the Eel River Delta) water body.

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 155286, Temperature, water	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318835

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Aquatic Life Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed temperature data for Adventure Scientists (Volunteer)* and determined that 0 of 0 samples are greater than the July-October maximum of 24 degrees Celcius and 1 of 1 sample is greater than the November-June maximum of 20 degrees, so that 1 of 1 sample exceeds the water quality objective.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Basin, Chapter III, General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states: Natural receiving water temperature of intrastate waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Water Board that such alteration in temperature does not adversely affect beneficial uses. At no time or place shall the temperature of any COLD water be increased more than 5 degrees Fahrenheit (F) above natural receiving water temperature.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

According to Carter (2008) the lethal temperature for spawning, incubation, and emergence life stages are 20 degrees C. The lethal temperatures for adult migration and holding, and juvenile migration and rearing is 24 degrees C.

Guideline Reference:

Spatial Representation:

This sample was collected at sampling station name: Eel Wild and Scenic River-40.47.124.11; station code: ADVENTURESCIENTISTS-40.47.124.11.

Temporal Representation:

This sample was collected on 6/24/2021.

Environmental Conditions:

QAPP Information:

QAPP for Adventure Scientists (Volunteer)*

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 155286, Temperature, water	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318244

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Aquatic Life Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed temperature data for SWAMP Perennial Stream Surveys and determined that 0 of 0 samples exceed the July-October maximum of 24 degrees Celcius and 0 of 1 sample exceeds the November-June maximum of 20 degrees Celcius, so that 0 of 1 sample exceeds the water quality objective.

Data Reference:

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

This sample was collected from sampling station name: Larabee Creek ~0.5mi above Frost Creek; station code: 111PS0322.

Temporal Representation:

This sample was collected on 6/20/2017.

Environmental Conditions:

QAPP Information:

QAPP for SWAMP Perennial Stream Surveys

QAPP Information Reference(s):

WQX from the NWQMP for the 2026 Integrated Report in Region 1

Line of Evidence (LOE) for Decision ID 155286, Temperature, water	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318770

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Aquatic Life Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed temperature data for EPA National Aquatic Resources Survey (NARS) and determined that 1 of 2 samples are greater than the July-October maximum of 24 degrees Celcius and 0 of 0 samples are greater than the November-June maximum of 20 degrees Celcius, so that 1 of 2 samples exceed the water quality objective.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

These samples were collected at sampling station name: Eel River; station code: NARS_WQX-CARM-1012.

Temporal Representation:

These samples were collected from 8/18/2014-8/19/2014.

Environmental Conditions:

QAPP Information:

QAPP for EPA National Aquatic Resources Survey (NARS)

QAPP Information Reference(s):

WQX from the NWQMP for the 2026 Integrated Report in Region 1

Line of Evidence (LOE) for Decision ID 155286, Temperature, water	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318906

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Aquatic Life Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed temperature data for Wiyot Tribe, California (Tribal) and determined that 0 of 17 samples are greater than the July-October maximum of 24 degrees Celcius and 1 of 28 samples are greater than the November-June maximum of 20 degrees Celcius, so that 1 of 45 samples exceed the water quality objective.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

These samples were collected at sampling station name: McNulty Slough; station code: WIYOT_WQX-MNS-1.

Temporal Representation:

These samples were collected from 9/2/2010-2/23/2012.

Environmental Conditions:

QAPP Information:

QAPP for Wiyot Tribe, California (Tribal)

QAPP Information Reference(s):

Data collected by a California Tribe QAPP Approved by U.S. EPA QAPP Reference

Line of Evidence (LOE) for Decision ID 155286, Temperature, water	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318839

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Aquatic Life Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed temperature data for QAPP for Adventure Scientists (Volunteer)* and determined that 0 of 0 samples are greater than the July-October maximum of 24 degrees C and 0 of 1 sample is greater than the November-June maximum of 20 degrees Celcius, so that 0 of 1 sample exceeds the water quality objective.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

This sample was collected at sampling station name: Eel Wild and Scenic River-40.58.124.15; station code: ADVENTURESCIENTISTS-40.58.124.15.

Temporal Representation:

This sample was collected on 6/24/2021.

Environmental Conditions:

QAPP Information:

QAPP for Adventure Scientists (Volunteer)*

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 155286, Temperature, water	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43802

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Water Temperature.

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): Natural receiving water temperature of intrastate waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Water Board that such alteration in temperature does not adversely affect beneficial uses. At no time or place shall the temperature of any COLD water be increased more than 5 degrees Fahrenheit (F) above natural receiving water temperature.

Objective/Criterion Reference:

Evaluation Guideline:

Per "Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids" (Carter 2008): The lethal temperature evaluation guideline for both steelhead adult migration & holding and juvenile growth & rearing of 24°C applies in this water body July-October. The lethal temperature evaluation guideline for salmonid spawning, egg incubation & fry emergence is 20C and applies November-June in this water body. See LOE ID 31520 for more information on natural temperature alterations and salmonid presence and periodicity in this water body.

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Larabee Creek - 111PS0013 ]

Temporal Representation:

Data was collected on a single day 8/19/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 155286, Temperature, water	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

3661

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Not Specified

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

This LOE is a placeholder to support a 303(d) listing decision made prior to 2006.

Data Reference:

Placeholder reference pre-2006 303(d)

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Unknown

Temporal Representation:

Unknown

Environmental Conditions:

Unknown

QAPP Information:

Unknown

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 155286, Temperature, water	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318831

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Aquatic Life Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

This sample was collected at sampling station name: Eel Wild and Scenic River-40.45.123.99; station code: ADVENTURESCIENTISTS-40.45.123.99.

Temporal Representation:

This sample was collected on 6/4/2021.

Environmental Conditions:

QAPP Information:

QAPP for Adventure Scientists (Volunteer)*

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 155286, Temperature, water	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318031

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Aquatic Life Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assess data for parent project SWAMP Stream Pollution Trends and determined that 0 of 7 samples exceed the July-October minimum temperature of 24 degrees Celcius and 0 of 0 samples exceed the November-June minimum temperature of 20 degrees Celcius, so that 0 of 7 sample exceed the water quality objective for temperature.

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

These samples were collected at sampling station name: Eel River at Fernbridge; station code: 111EELFRN

Temporal Representation:

These samples were collected from 9/23/2013-9/15/2022

Environmental Conditions:

QAPP Information:

QAPP for SWAMP Stream Pollution Trends

QAPP Information Reference(s):

WQX from the NWQMP for the 2026 Integrated Report in Region 1

Line of Evidence (LOE) for Decision ID 155286, Temperature, water	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318843

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Aquatic Life Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed temperature data for Adventure Scientists (Volunteer)* and determined that 0 of 0 sample is greater than the July-October maximum of 24 degrees Celcius and 0 of 1 sample is greater than the November-June maximum of 20 degree Celcius, so that 0 of 1 sample exceeds the water quality objective.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

This sample was collected at sampling station: Eel Wild and Scenic River-40.64.124.28; station code: ADVENTURESCIENTISTS-40.64.124.28.

Temporal Representation:

This sample was collected on 6/25/2021.

Environmental Conditions:

QAPP Information:

QAPP for Adventure Scientists (Volunteer)*

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 155286, Temperature, water	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

46504

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

One of the 53 samples exceeded the lethal temperature evaluation guideline. This LOE re-analyzes the data from LOE 5590, which incorrectly stated that data could not be compared to the lethal threshold.

Data Reference:

Wiyot Tribe Water Quality Monitoring Program. Data for multiple parameters in McNultly Slough, Humboldt Bay Entrance, Indian Island, Mad River Slough, and Reservation Wetland, December 2004 to December 2006

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Per the Thermal Plan (SWRCB 1972) for estuaries: (A) For existing discharges: (1) Elevated temperature waste discharges shall comply with the following: (a) The maximum temperature shall not exceed the natural receiving water temperature by more than 20°F. (b) Elevated temperature waste discharges either individually or combined with other discharges shall not create a zone, defined by water temperatures of more than 1°F above natural receiving water temperature, which exceeds 25 percent of the cross-sectional area of a main river channel at any point. (c) No discharge shall cause a surface water temperature rise greater than 4°F above the natural temperature of the receiving waters at any time or place. (d) Additional limitations shall be imposed when necessary to assure protection of beneficial uses. (2) Thermal waste discharges shall comply with the provisions of (A)(1) above and, in addition, the maximum temperature of thermal waste discharges shall not exceed 86°F. (B) For new discharges: (1) Elevated temperature waste discharges shall comply with item (A)(1) above. (2) Thermal waste discharges having a maximum temperature greater than 4°F above the natural temperature of the receiving water are prohibited. (3) Additional limitations shall be imposed when necessary to assure protection of beneficial uses. Per the Basin Plan (NCRWQCB 2011): The natural receiving water temperature of intrastate waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Water Board that such alteration in temperature does not adversely affect beneficial uses. At no time or place shall the temperature of any COLD water be increased by more than 5°F above natural receiving water temperature.

Objective/Criterion Reference:

Water Quality Control Plan for Control of Temperature in the Coastal and Interstate Waters and Enclosed Bays and Estuaries of California (Thermal Plan). State Water Resources Control Board

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The temperatures samples were collected by the Wiyot Tribe at McNulty Slough. The site is on the seaward side of the tide gate located just south of McNulty Lane, adjacent to the old Wiyot Rancheria.

Temporal Representation:

The temperature samples were collected every two weeks from December 2004 to December 2006. Samples were collected during mid and high tides. The sonde was deployed for approximately 15 minutes, with a 3-5 minute equilibration period and an 8-10 minute sample period with 4 second intervals.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Samples were collected according to Wiyot Tribe¿s ¿Draft Quality Assurance Program Plan (QAPP) for Water Quality Assessment and Monitoring¿ (McKernan et al. 2004).

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 155286, Temperature, water	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

46793

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

The Lower Eel River TMDLs for Temperature and Sediment were approved by the USEPA on December 18, 2007 (USEPA 2007). The conclusions from the TMDL document for the mainstem and tributaries respectively are as follows.

MAINSTEM LOWER EEL RIVER: The USEPA concludes that a temperature TMDL is not needed for the mainstem of the Lower Eel River as modeling results reflect that alterations in shade and flow have not resulted in water temperature changes. However, the TMDL document states that while modeling estimated that changes in riparian vegetation do not result in significant changes in shade on the main channel, this is primarily due to the fact that the stream channel is so wide. USEPA concluded that sediment has contributed to channel widening, thereby resulting in less shading over the channel and contributing to temperature impairment. In other words, sediment in the mainstem of the Lower Eel River is causing temperature impairment. Thus, a sediment TMDL was established, which will address the temperature impairment of the mainstem of the Lower Eel River.

TRIBUTARIES TO THE LOWER EEL RIVER: The USEPA concludes that tributary streams do not meet water quality standards for temperature to significant changes in stream shading. Therefore, temperature TMDLs are established for the tributaries to the Lower Eel River.

Data Reference:

Lower Eel River Total Maximum Daily Loads for Temperature and Sediment.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Information pertains to the Eel River HU, Lower Eel River HA (includes the Eel River Delta).

Temporal Representation:

Data are reflective of current conditions in this water body.

Environmental Conditions:

QAPP Information:

Information is considered to be of adequate quality for the Integrated Report process.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 155286, Temperature, water	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

31520

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

The following process is utilized to interpret the narrative temperature objective in the Basin Plan for impairment assessments. Step 1: Determine if temperatures reflect natural conditions. If Yes, then the water body is not considered impaired, if No, then go to Step 2. Step 2: Determine if temperatures adversely affect beneficial uses. If Yes, then the water body is considered impaired, if No , then go to Step 3. Step 3: Determine if temperatures are increased by 5 degrees F. If Yes, then water body is impaired, if No, then water body is not impaired.

Data Reference:

Presentation: Interpreting Temperature Standards in the North Coast Region. North Coast Regional Water Quality Control Board.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

EVIDENCE OF ALTERATION OF NATURAL RECEIVING WATER TEMPERATURE: Water temperatures in the Eel River HU, Lower Eel River HA (includes the Eel River Delta), have been altered and do not reflect natural receiving water temperatures. For instance, the Lower Eel River TMDLs for Temperature and Sediment states that shade and temperature modeling, which compared current conditions to historical vegetation conditions, found that estimated natural temperatures are cooler than current temperatures (USEPA 2007). EVIDENCE OF SALMONID PRESENCE & LIFE CYCLE USE: Coho, steelhead and Chinook are present in the Lower Eel River HA (USEPA 2007). Rearing occurs year round and spawning/ incubation/ emergence occurs from November to June (Busby et al. 1996; CDFG 2004; Myers et al. 1998). Non-core rearing occurs in the mainstem Eel River, while core rearing occurs in tributaries.

Guideline Reference:

Recovery Strategy for California Coho Salmon: Report to the California Fish and Game Commission

Guideline Reference:

Lower Eel River Total Maximum Daily Loads for Temperature and Sediment.

Guideline Reference:

Status Review of Chinook Salmon from Washington, Idaho, Oregon, and California.

Guideline Reference:

Status Review of West Coast Steelhead from Washington, Idaho, Oregon, and California

Spatial Representation:

Information pertains to the Eel River HU, Lower Eel River HA (includes the Eel River Delta).

Temporal Representation:

Data are reflective of current conditions in this water body.

Environmental Conditions:

QAPP Information:

Information is considered to be of adequate quality for the Integrated Report process.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 155286, Temperature, water	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

5590

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Aquatic Life Use:

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

The water temperatures of McNulty Slough do not reflect natural conditions as the environmental factors that influence water temperature have been altered by human activities in the Eel River watershed. For instance, the Lower Eel River TMDLs for Temperature and Sediment (USEPA 2007) states that shade and temperature modeling, which compared current conditions to historical vegetation conditions, found that natural temperatures are cooler than estimated current temperatures. The two modeled tributaries are Salt River and Larabee Creek, with the results applied to all other tributaries, including McNulty Slough. In order to determine if temperature adversely affects beneficial uses, staff attempted to compare temperature data to the 24°C lethal temperature evaluation guideline from Carter (2008). The Wiyot Tribe collected 53 surface water temperature samples in McNulty Slough. None of these samples were collected over 7 consecutive days and staff were therefore unable to compare them to the guideline. There was 1 instance where the average water temperature over a 3-minute period on 06/29/2005 exceeded 24°C. Data are summarized by the Wiyot Tribe (Wiyot 2007).

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Per the Thermal Plan (SWRCB 1972) for estuaries: (A) For existing discharges: (1) Elevated temperature waste discharges shall comply with the following: (a) The maximum temperature shall not exceed the natural receiving water temperature by more than 20°F. (b) Elevated temperature waste discharges either individually or combined with other discharges shall not create a zone, defined by water temperatures of more than 1°F above natural receiving water temperature, which exceeds 25 percent of the cross-sectional area of a main river channel at any point. (c) No discharge shall cause a surface water temperature rise greater than 4°F above the natural temperature of the receiving waters at any time or place. (d) Additional limitations shall be imposed when necessary to
assure protection of beneficial uses. (2) Thermal waste discharges shall comply with the provisions of (A)(1) above and, in addition, the maximum temperature of thermal waste discharges shall not exceed 86°F. (B) For new discharges: (1) Elevated temperature waste discharges shall comply with item (A)(1) above. (2) Thermal waste discharges having a maximum temperature greater than 4°F above the natural temperature of the receiving water are prohibited.
(3) Additional limitations shall be imposed when necessary to assure protection of beneficial uses. Per the Basin Plan (NCRWQCB 2007): The natural receiving water temperature of intrastate waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Water Board that such alteration in temperature does not adversely affect beneficial uses. At no time or place shall the temperature of any COLD water be increased by more than 5°F above natural receiving water temperature.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - North Coast Region (Region 1)

Objective/Criterion Reference:

Water Quality Control Plan for Control of Temperature in the Coastal and Interstate Waters and Enclosed Bays and Estuaries of California (Thermal Plan). State Water Resources Control Board

Evaluation Guideline:

Per "Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids" (Carter 2008), the lethal temperature evaluation guideline for both the steelhead adult migration and holding and the steelhead juvenile growth and rearing life stages is 24°C. This guideline is for chronic exposure and requires data that is measured for at least 7 consecutive days as salmonids may survive brief periods at these levels.

Guideline Reference:

Spatial Representation:

The temperatures samples were collected by the Wiyot Tribe at McNulty Slough. The site is on the seaward side of the tide gate located just south of McNulty Lane, adjacent to the old Wiyot Rancheria.

Temporal Representation:

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Samples were collected according to Wiyot Tribe¿s ¿Draft Quality Assurance Program Plan (QAPP) for Water Quality Assessment and Monitoring¿ (McKernan et al. 2004).

QAPP Information Reference(s):


DECISION ID	101135	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Aldrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3 of the Listing Policy. Under section 3 a single line(s) of evidence are necessary to assess listing status. One lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3.None of the samples exceeded the objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

Line of Evidence (LOE) for Decision ID 101135, Aldrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122336

Pollutant:

Aldrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Aldrin, Total. Ten sample results were not used in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to (1) update the numeric objective, and (2) evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. The established numeric criteria for aldrin to protect of human health from the consumption of water and organisms is 0.00013 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Objective/Criterion Reference:

Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	157226	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Alkalinity as CaCO3
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 157226, Alkalinity as CaCO3	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

323072

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP Perennial Stream Surveys data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Alkalinity as CaCO3.

Data Reference:

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The USEPA recommended alkalinity criterion continuous concentration (CCC) for the protection of aquatic life in freshwater is a minimum value of 20,000 ug/L (4-day average).

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 111PS0322 (Larabee Creek ~0.5mi above Frost Creek).

Temporal Representation:

The samples were collected between the dates of 2017-06-20 and 2017-06-20

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for DFW_ABL_Monitoring.


DECISION ID	76587	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Ammonia
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2016)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	"This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line(s) of evidence are necessary to assess listing status. Three lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None of the fifteen samples exceeded the objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met."

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

Line of Evidence (LOE) for Decision ID 76587, Ammonia	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

104152

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed DFW_ABL_Monitoring data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality standard for Ammonia as N.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The USEPA Health Advisory for lifetime exposure to Ammonia as a drinking water level is a concentration of 30 mg/L

Guideline Reference:

2012 Edition of the Drinking Water Standards and Health Advisories

Spatial Representation:

The samples were collected at 1 monitoring site(s) (111CR1012)

Temporal Representation:

The samples were collected between the dates of 2014-08-18 and 2014-08-18

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program

Line of Evidence (LOE) for Decision ID 76587, Ammonia	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

34575

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

The sample does not exceed the water USEPA Temperature and pH-Dependent values of the CCC (Chronic Criterion) for Fish Early Life Stages Present for ammonia. The datum was reported as a quantitation limit. This quantitation limit is less than or equal to the water quality standard, the value will be considered as meeting the water quality standard, objective, criterion, or evaluation guideline.

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Update of Ambient Water Quality Criteria for Ammonia (USEPA 1999): Where salmonids and fish early life stages are present, the 30-day average concentration (criterion continuous concentration or CCC) of total ammonia (as mg N/L) in freshwater are not to be exceeded more than once every three years on average. The CCC values are based on pH, temperature, and the presence of early life stages of fish. The CCC formula is found on p.83 and the table of CCC values are found on p.87.

Guideline Reference:

1999 Update of Ambient Water Quality Criteria for Ammonia

Spatial Representation:

Samples were collected at 111PS0013 (Larabee Creek).

Temporal Representation:

The sample was collected on 8/19/2008.

Environmental Conditions:

QAPP Information:

SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 76587, Ammonia	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

26316

Pollutant:

Ammonia as Nitrogen

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Aquatic Life Use:

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

None of the 15 ammonia as nitrogen samples collected from Lower Mainstem Eel River exceed the objective. The samples were collected as part of the Surface Water Ambient Water Monitoring Program (SWAMP). The data are found in the SWAMP Summary Report for the North Coast Region for Years 2000-2006 (NCRWQCB 2008).

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Per the Basin Plan (NCRWQCB 2007): All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - North Coast Region (Region 1)

Evaluation Guideline:

Per the National Recommended Water Quality Criteria (USEPA 2006): The 1-hour average concentration (acute criterion or CMC) of total ammonia nitrogen (in mg N/L) for freshwater where salmonid fish are present, which is not to be exceeded more than once every three years on average, is calculated using the following equation: CMC=0.275/(1+10^(7.204 - pH)) + 39.0/(1+10^(pH - 7.204)).

Guideline Reference:

Spatial Representation:

Samples were collected from the Lower Mainstem Eel River at Holmes (SWAMP Station ID 111EELHOL). Samples were collected from well-mixed flows in glides or riffles.

Temporal Representation:

Samples were collected from 14 site visits from February 2002 to June 2005. Most of the site visits corresponded to fall, winter, spring and early summer seasonal conditions.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (Puckett 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	157207	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Arsenic
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 157207, Arsenic	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322003

Pollutant:

Arsenic

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The evaluation guideline for arsenic is the probable effect concentration (PEC) of 33 mg/kg dry weight (MacDonald et al., 2000a).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2020-08-26

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 157207, Arsenic	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43250

Pollutant:

Arsenic

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for arsenic is 33 mg/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN ]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157207, Arsenic	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43260

Pollutant:

Arsenic

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for arsenic is 33 mg/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN ]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157207, Arsenic	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122339

Pollutant:

Arsenic

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for Arsenic, Total. This LOE re-assesses data from LOE 21528 from the 2010 Integrated Report. Data were re-assessed in order to (1) update the numeric objective, and (2) evaluate these data in their own LOE, instead of being evaluated in the same LOE as other metals data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): Waters designated for use as domestic or municipal supply (MUN) shall not contain concentrations of chemical constituents in excess of the limits specified in California Code of Regulations, Title 22, Chapter 15. The maximum contaminant level listed in Table 64431-A for arsenic is 0.010 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	165747	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Atrazine
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165747, Atrazine	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122340

Pollutant:

Atrazine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Atrazine, Total. Seven sample results were not used in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to (1) update the numeric objective, and (2) evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): Waters designated for use as domestic or municipal supply (MUN) shall not contain concentrations of chemical constituents in excess of the limits specified in California Code of Regulations, Title 22, Chapter 15. The maximum contaminant level listed in Table 64431-A for atrazine is 1 ug/L.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 6/9/2002-4/25/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	104136	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Azinphos, Ethyl (Ethyl Guthion)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line(s) of evidence are necessary to assess listing status. One line(s) of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None samples exceeded the objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

Line of Evidence (LOE) for Decision ID 104136, Azinphos, Ethyl (Ethyl Guthion)	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122341

Pollutant:

Azinphos, Ethyl (Ethyl Guthion)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Azinphos Ethyl, Total. Ten sample results were not used in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Per the Basin Plan (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. There shall be no bioaccumulation of pesticide concentrations found in bottom sediments or aquatic life. Waters designated for use as domestic or municipal supply shall not contain concentrations of pesticides in excess of the limiting concentrations set forth in California Code of Regulations, Title 22, Division 4, Chapter 15, Article 4, Section 64444, and listed in Table 3.2 of the Basin Plan.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

According to National Academy of Sciences Water Quality Criteria (1972), the Azinphos, Ethyl (Ethyl Guthion) criteria is 0.0875 mg/L. (EPA-R3-73-033)

Guideline Reference:

National Academy of Sciences. Water Quality Criteria 1972. EPA-R3-73-033. Washington, D.C.: U.S. Environmental Protection Agency

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	169270	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Benthic Community Effects
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Benthic Community Effects are being considered for placement on the CWA section 303(d) List under sections 3.9 of the Listing Policy. Under section 3.9, additional lines of evidence (LOEs) associating the Benthic Community Effects decision with a water or sediment concentration of pollutants other than benthic-macroinvertebrate bioassessment or habitat assessment LOEs are necessary to place a water body on the 303(d) List for Benthic Community Effects. Two lines of evidence evaluating benthic-macroinvertebrate bioassessment data are available in the administrative record to assess this indicator. Zero of one benthic-macroinvertebrate samples exceed the Index of Biological Integrity (IBI) impairment threshold. Zero of one benthic-macroinvertebrate samples exceed the California Stream Condition Index (CSCI) impairment threshold. These data indicate that the waterbody is likely unimpaired for Benthic Community Effects and therefore no other pollutant LOEs need be associated with this decision at this time. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing Benthic Community Effects in this waterbody segment on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one benthic-macroinvertebrate bioassessment samples had CSCI scores below 0.79. Therefore, this water body is not exceeding the water quality threshold for the protection of the COLD beneficial use. The available information indicates that the waterbody/pollutant combination should not be placed on the 303(d) List of impaired waters at this time. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 169270, Benthic Community Effects	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

32167

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

The one samples collected had an IBI score above 52. The IBI score was 60.

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The Index of Biological Integrity (IBI) is a multi-metric assessment that employs biological metrics that respond to a habitat or water quality impairment. Each of the biological metrics measured at a site are converted to an IBI score then summed. These cumulative scores are then ranked. For the Northern California IBI, sites with scores below 52 are considered to have impaired conditions.

Guideline Reference:

Development of a Benthic Index of Biotic Integrity (B-IBI) for Wadeable Streams in Northern Coastal California and its Application to Regional 305(b) Assessment

Spatial Representation:

The sample was collected at Larabee Creek, station code 111PS0013.

Temporal Representation:

The sample was collected on August 19, 2008.

Environmental Conditions:

QAPP Information:

The sample was collected for the SWAMP Perennial Streams Assessment.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 169270, Benthic Community Effects	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

352584

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 111PS0322 to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the water quality standard. CSCI scores were from 1.017644257 to 1.017644257 .

Data Reference:

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. Compliance with this objective will be determined by use of indicator organisms, analyses of species diversity, population density, growth anomalies, bioassays of appropriate duration, or other appropriate methods as specified by the Regional Water Board (NCRWQCB 2018).

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The California Stream Condition Index (CSCI) is a biological scoring tool that helps aquatic resource managers translate complex data about benthic macroinvertebrates found living in a stream into an overall measure of stream health. The CSCI score is calculated by comparing the expected condition with actual (observed) results (Rhen, A.C. et al., 2015). CSCI scores range from 0 (highly degraded) to greater than 1 (equivalent to reference). CSCI scoring of biological condition are as follows (per the scientific paper supporting the development of the CSCI scoring tool): greater than or equal to 0.92 = likely intact condition, 0.91 to 0.80 = possibly altered condition, 0.79 to 0.63 = likely altered condition, less than or equal to 0.62 = very likely altered condition. Sites with scores below 0.79 are considered to have exceeded the water quality objective for the aquatic life beneficial use.)

Guideline Reference:

Bioassessment in complex environments: designing an index for consistent meaning in different settings

Spatial Representation:

The samples were collected at 1 monitoring site: 111PS0322 (Larabee Creek ~0.5mi above Frost Creek).

Temporal Representation:

Samples were collected from 2017-06-20 to 2017-06-20.

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):


DECISION ID	157224	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Bifenthrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 157224, Bifenthrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43499

Pollutant:

Bifenthrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for bifenthrin is the median lethal concentration (LC50) of 0.43 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.43 ug/g is the geometric mean of LC50 values for bifenthrin from Amweg et al. (2005) and Amweg and Weston (2007).

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Guideline Reference:

Effect of sediment-associated pyrethroids, fipronil, and metabolites on Chironomus tentans growth rate, body mass, condition index, immobilization, and survival. Environ. Toxicol. Chem. 27(12):2582-2590.

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157224, Bifenthrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43498

Pollutant:

Bifenthrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Guideline Reference:

Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157224, Bifenthrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322021

Pollutant:

Bifenthrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. There shall be no bioaccumulation of pesticide concentrations found in bottom sediments or aquatic life. (Water Quality Control Plan for the North Coast Region)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Guideline Reference:

Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2018-09-12

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008


DECISION ID	165748	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Bolstar
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165748, Bolstar	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122342

Pollutant:

Bolstar

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Bolstar, Total. Ten samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	157208	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Cadmium
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 157208, Cadmium	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322033

Pollutant:

Cadmium

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The evaluation guideline for cadmium is the probable effect concentration (PEC) of 4.98 mg/kg dry weight (MacDonald et al., 2000a).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2020-08-26

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

Line of Evidence (LOE) for Decision ID 157208, Cadmium	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122343

Pollutant:

Cadmium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for Cadmium, Total. This LOE re-assesses data from LOE 21528 from the 2010 Integrated Report. Data were re-assessed in order to (1) update the numeric objective, and (2) evaluate these data in their own LOE, instead of being evaluated in the same LOE as other metals data.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): Waters designated for use as domestic or municipal supply (MUN) shall not contain concentrations of chemical constituents in excess of the limits specified in California Code of Regulations, Title 22, Chapter 15. The maximum contaminant level listed in Table 64431-A for cadmium 0.005 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 157208, Cadmium	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43634

Pollutant:

Cadmium

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for cadmium is 4.98 mg/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN ]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157208, Cadmium	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43633

Pollutant:

Cadmium

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for cadmium is 4.98 mg/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN ]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	157209	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Chlordane
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 157209, Chlordane	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322045

Pollutant:

Chlordane

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. There shall be no bioaccumulation of pesticide concentrations found in bottom sediments or aquatic life. (Water Quality Control Plan for the North Coast Region)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The evaluation guideline for chlordane is the probable effect concentration (PEC) of 17.6 ug/kg dry weight (MacDonald et al., 2000a).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2017-09-20

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 157209, Chlordane	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

33673

Pollutant:

Chlordane

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Zero of 1 sample collected did not exceed the criteria for chlordane concentration (Sum of trans-Chlordane, cis-Chlordane, cis-Nonachlor, trans-Nonachlor, and Oxychlordane).

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. Waters shall not contain substances in concentrations that result in deposition of material that causes nuisance or adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

The Probable Effect Concentration for Chlordane in freshwater sediments is 17.6 ug/kg.

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected at the following station 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

One sample was collected on 10/15/2008.

Environmental Conditions:

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	158429	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Chloride
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 158429, Chloride	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

25432

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

None of the 14 chloride samples collected in the Lower Mainstem Eel River exceed the evaluation guideline. The samples were collected as part of the Surface Water Ambient Water Monitoring Program (SWAMP). The data are found in the SWAMP Summary Report for the North Coast Region for Years 2000-2006 (NCRWQCB 2008).

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Per the Basin Plan (NCRWQCB 2007): Waters shall not contain taste- or odor-producing substances in concentrations that impart undesirable tastes or odors to fish flesh or other edible products of aquatic origin, or that cause nuisance or adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - North Coast Region (Region 1)

Evaluation Guideline:

Per 22 CCR 64449: The recommended Secondary Maximum Contaminant Level for chloride is 250 mg/L.

Guideline Reference:

Title 22. Division 4. Chapter 15. Sections 64400 et seq. California Code of Regulations

Spatial Representation:

Samples were collected from the Lower Mainstem Eel River at Holmes (SWAMP Station ID 111EELHOL). Samples were collected from well-mixed flows in glides or riffles.

Temporal Representation:

Samples were collected from 14 site visits from February 2002 to June 2005. Most of the site visits corresponded to fall, winter, spring and early summer seasonal conditions.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 158429, Chloride	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

328137

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed EPA National Aquatic Resources Survey (NARS) data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chloride.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2018): Waters designated for use as domestic or municipal supply (MUN) shall not contain concentrations of chemical constituents in excess of the limits specified in California Code of Regulations, Title 22, Chapter 15. The secondary maximum contaminant level listed in Table 64449-B for chloride is 250 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: NARS_WQX-CARM-1012 (Eel River).

Temporal Representation:

The samples were collected between the dates of 2014-08-18 and 2014-08-18

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 158429, Chloride	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

44093

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Secondary Maximum Contaminant Levels and Compliance. CCR Title 22 section 64449.

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Larabee Creek - 111PS0013 ]

Temporal Representation:

Data was collected on a single day 8/19/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 158429, Chloride	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

106756

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for DFW_ABL_Monitoring.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s) (111CR1012)

Temporal Representation:

The samples were collected between the dates of 2014-08-18 and 2014-08-18

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program


DECISION ID	157210	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Chlorpyrifos
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 157210, Chlorpyrifos	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43517

Pollutant:

Chlorpyrifos

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for chlorpyrifos is the median lethal concentration (LC50) of 1.77 ug/g and is normalized by the percentage of organic carbon in the sediment sample (Amweg and Weston, 2007).

Guideline Reference:

Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157210, Chlorpyrifos	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322057

Pollutant:

Chlorpyrifos

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. There shall be no bioaccumulation of pesticide concentrations found in bottom sediments or aquatic life. (Water Quality Control Plan for the North Coast Region)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The evaluation guideline for chlorpyrifos is the median lethal concentration (LC50) of 1.77 ug/g and is normalized by the percentage of organic carbon in the sediment sample (Amweg and Weston, 2007).

Guideline Reference:

Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2017-09-20

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 157210, Chlorpyrifos	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43516

Pollutant:

Chlorpyrifos

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for chlorpyrifos is the median lethal concentration (LC50) of 1.77 ug/g and is normalized by the percentage of organic carbon in the sediment sample (Amweg and Weston, 2007).

Guideline Reference:

Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	104165	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Chlorpyrifos, methyl
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One lines of evidence is available in the administrative record to assess this pollutant. None of the samples exceed the objective for the MUN beneficial use(s). Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of 20 samples exceed the objective for the MUN beneficial use(s) and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

Line of Evidence (LOE) for Decision ID 104165, Chlorpyrifos, methyl	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122344

Pollutant:

Chlorpyrifos, methyl

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 20 samples exceed the criterion for Chlorpyrifos Methyl, Total. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. The USEPA Health Advisory for life time exposure to Chlorpyrifos is 0.002 mg/L (EPA 820-R-11-002 Drinking Water Standards and Health Advisories, 2011).

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	157230	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Chromium
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Five lines of evidence are available in the administrative record to assess this pollutant. Four of seven sediment samples exceed the objective, but there is no toxicity data. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Four of seven sediment samples exceed the objective, but there is no toxicity data and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 157230, Chromium	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322067

Pollutant:

Chromium

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The evaluation guideline for chromium is the probable effect concentration (PEC) of 111 mg/kg dry weight (MacDonald et al., 2000a).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2020-08-26

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

Line of Evidence (LOE) for Decision ID 157230, Chromium	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

46851

Pollutant:

Chromium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Zero of fifteen samples exceeded the chromium objective. This LOE re-assesses data from LOE 21528 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other metals data.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): Waters designated for use as domestic or municipal supply (MUN) shall not contain concentrations of chemical constituents in excess of the limits specified in California Code of Regulations, Title 22, Chapter 15. The maximum contaminant level listed in Table 64431-A for chromium 0.05 mg/L.

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected from the Lower Mainstem Eel River at Holmes (SWAMP Station ID 111EELHOL). Samples were collected from well-mixed flows in glides or riffles.

Temporal Representation:

Samples were collected from 15 site visits from February 2002 to June 2005. Most of the site visits corresponded to fall, winter, spring and early summer seasonal conditions.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 157230, Chromium	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

46849

Pollutant:

Chromium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Zero of 6 samples exceeded the chromium objective. This LOE re-assesses data from LOE 25250 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other metals data.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): Waters designated for use as domestic or municipal supply (MUN) shall not contain concentrations of chemical constituents in excess of the limits specified in California Code of Regulations, Title 22, Chapter 15. The maximum contaminant level listed in Table 64431-A for chromium 0.05 mg/L.

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected by the Wiyot Tribe at McNulty Slough. The site is on the seaward side of the tide gate located just south of McNulty Lane, adjacent to the old Wiyot Rancheria.

Temporal Representation:

Samples were collected as grab samples on May 4, August 19, and December 2, 2005, and on March 17, July 20, and November 3, 2006.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Samples were collected according to Wiyot Tribes "Draft Quality Assurance Program Plan (QAPP) for Water Quality Assessment and Monitoring" (McKernan et al. 2004).

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 157230, Chromium	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43713

Pollutant:

Chromium

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 1 of 1 samples exceed the criterion for Chromium.

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for chromium is 111 mg/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN ]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157230, Chromium	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43697

Pollutant:

Chromium

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for chromium is 111 mg/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN ]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	165749	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Ciodrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165749, Ciodrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122346

Pollutant:

Ciodrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Ciodrin, Total. Ten samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	157211	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Copper
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 157211, Copper	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43777

Pollutant:

Copper

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for copper is 149 mg/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN ]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157211, Copper	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322090

Pollutant:

Copper

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The evaluation guideline for copper is the probable effect concentration (PEC) of 149 mg/kg dry weight (MacDonald et al., 2000a).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2020-08-26

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

Line of Evidence (LOE) for Decision ID 157211, Copper	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122348

Pollutant:

Copper

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for Copper, Total. This LOE re-assesses data from LOE 21528 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other metals data.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Objective/Criterion Reference:

Secondary Maximum Contaminant Levels and Compliance. CCR Title 22 section 64449.

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 157211, Copper	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43778

Pollutant:

Copper

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for copper is 149 mg/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN ]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	157227	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Cyfluthrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 157227, Cyfluthrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322101

Pollutant:

Cyfluthrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. There shall be no bioaccumulation of pesticide concentrations found in bottom sediments or aquatic life. (Water Quality Control Plan for the North Coast Region)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The evaluation guideline for cyfluthrin is the median lethal concentration (LC50) of 1.1 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 1.1 ug/g is the geometric mean of LC50 values for cyfluthrin (Amweg et al., 2005).

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2017-09-20

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 157227, Cyfluthrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43535

Pollutant:

Cyfluthrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157227, Cyfluthrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43534

Pollutant:

Cyfluthrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	157229	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Cyhalothrin, Lambda
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 157229, Cyhalothrin, Lambda	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322105

Pollutant:

Cyhalothrin, Lambda

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. There shall be no bioaccumulation of pesticide concentrations found in bottom sediments or aquatic life. (Water Quality Control Plan for the North Coast Region)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The evaluation guideline for lambda-cyhalothrin is the median lethal concentration (LC50) of 0.44 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.44 ug/g is the geometric mean of LC50 values for lambda-cyhalothrin (Amweg et al., 2005).

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2017-09-20

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 157229, Cyhalothrin, Lambda	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43573

Pollutant:

Cyhalothrin, Lambda

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157229, Cyhalothrin, Lambda	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43572

Pollutant:

Cyhalothrin, Lambda

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	157225	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Cypermethrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 157225, Cypermethrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322122

Pollutant:

Cypermethrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP Stream Pollution Trends data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for Cypermethrin, Total. Although a total of 6 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. There shall be no bioaccumulation of pesticide concentrations found in bottom sediments or aquatic life. (Water Quality Control Plan for the North Coast Region)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The evaluation guideline for cypermethrin is the median lethal concentration (LC50) of 0.3 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.3 ug/g is the geometric mean of LC50 values for cypermethrin from Maund et al., (2002).

Guideline Reference:

Partitioning, bioavailability, and toxicity of the pyrethroid insecticide cypermethrin in sediments. Environmental Toxicology and Chemistry 21:9-15

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2017-09-20

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 157225, Cypermethrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43620

Pollutant:

Cypermethrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Partitioning, bioavailability, and toxicity of the pyrethroid insecticide cypermethrin in sediments. Environmental Toxicology and Chemistry 21:9-15

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157225, Cypermethrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43546

Pollutant:

Cypermethrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Partitioning, bioavailability, and toxicity of the pyrethroid insecticide cypermethrin in sediments. Environmental Toxicology and Chemistry 21:9-15

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	161335	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	DDD (Dichlorodiphenyldichloroethane)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 161335, DDD (Dichlorodiphenyldichloroethane)	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

33565

Pollutant:

DDD (Dichlorodiphenyldichloroethane)

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Zero of 1 sample collected for sum DDD (DDD(o,p') + DDD(p,p')) exceeded the evaluation guideline.

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. Waters shall not contain substances in concentrations that result in deposition of material that causes nuisance or adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for sum of DDD is 28.0 ug/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected at the following station 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

The samples were collected on 10/15/2008.

Environmental Conditions:

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 161335, DDD (Dichlorodiphenyldichloroethane)	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122443

Pollutant:

DDD (Dichlorodiphenyldichloroethane)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for DDD(o,p'), Total. Twenty samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 161335, DDD (Dichlorodiphenyldichloroethane)	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322130

Pollutant:

DDD (Dichlorodiphenyldichloroethane)

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. There shall be no bioaccumulation of pesticide concentrations found in bottom sediments or aquatic life. (Water Quality Control Plan for the North Coast Region)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The evaluation guideline for the sum of DDD is the probable effect concentration (PEC) of 28 ug/kg dry weight (MacDonald et al., 2000a).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2017-09-20

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008


DECISION ID	161324	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	DDE (Dichlorodiphenyldichloroethylene)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 161324, DDE (Dichlorodiphenyldichloroethylene)	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122456

Pollutant:

DDE (Dichlorodiphenyldichloroethylene)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for DDE(o,p'), Total. Twenty samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 161324, DDE (Dichlorodiphenyldichloroethylene)	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

33551

Pollutant:

DDE (Dichlorodiphenyldichloroethylene)

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Zero of 1 sample collected for sum DDE (DDE(o,p') + DDE(p,p')) exceeded the evaluation guideline.

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. Waters shall not contain substances in concentrations that result in deposition of material that causes nuisance or adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for sum of DDE is 31.3 ug/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected at the following station 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

The samples were collected on 10/15/2008.

Environmental Conditions:

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 161324, DDE (Dichlorodiphenyldichloroethylene)	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322139

Pollutant:

DDE (Dichlorodiphenyldichloroethylene)

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. There shall be no bioaccumulation of pesticide concentrations found in bottom sediments or aquatic life. (Water Quality Control Plan for the North Coast Region)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The evaluation guideline for Sum DDE from MacDonald et al., 2000a which states that the probable effect concentration for Sum DDE is 31.3 ug/kg. (dw = Dry Weight)

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2017-09-20

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):


DECISION ID	161309	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	DDT (Dichlorodiphenyltrichloroethane)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 161309, DDT (Dichlorodiphenyltrichloroethane)	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

33605

Pollutant:

DDT (Dichlorodiphenyltrichloroethane)

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Zero of 1 sample collected for Total DDTs (sum DDD + sum DDE + sum DDT) exceeded the evaluation guideline.

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. Waters shall not contain substances in concentrations that result in deposition of material that causes nuisance or adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for total DDTs is 572 ug/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected at the following station 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

The samples were collected on 10/15/2008.

Environmental Conditions:

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 161309, DDT (Dichlorodiphenyltrichloroethane)	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

25626

Pollutant:

DDT (Dichlorodiphenyltrichloroethane)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

One DDT sample collected in the Lower Eel River HA had a detectable level of DDT and the sample exceeds the evaluation guideline. The sample concentration was reported as detected not quantifiable (DNQ), with estimated value of .003 ug/l (method detection limit of 0.002 ug/l, reporting limit of .005 ug/l). There were also an additional 9 samples from the Lower Eel River HA, which were non-detect. However, these non-detect data could not be utilized in this assessment because the detection limit for DDT is above the evaluation guideline. Per the listing policy, when a sample value is less than the quantitation limit, and the quantitation limit is greater than the evaluation guideline, the result shall not be used in the analysis. The samples were collected as part of the Surface Water Ambient Water Monitoring Program (SWAMP) (NCRWQCB 2008).

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). DDT, DDE, and DDD data from SWAMP Sampling for Years 2001-2006. North Coast Regional Water Quality Control Board.

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Per the Basin Plan (NCRWQCB 2007): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. There shall be no bioaccumulation of pesticide concentrations found in bottom sediments or aquatic life. Waters designated for use as domestic or municipal supply shall not contain concentrations of pesticides in excess of the limiting concentrations set forth in California Code of Regulations, Title 22, Division 4, Chapter 15, Article 4, Section 64444, and listed in Table 3.2 of the Basin Plan.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - North Coast Region (Region 1)

Evaluation Guideline:

Per the National Recommended Water Quality Criteria (USEPA 2006): The recommended criterion for DDT for the protection of source waters for human health consumption of water and organisms is 0.00022 ug/l.

Guideline Reference:

Spatial Representation:

Samples were collected from the Lower Mainstem Eel River at Holmes (SWAMP Station ID 111EELHOL). Samples were collected from well-mixed flows in glides or runs.

Temporal Representation:

Samples were collected from 10 site visits from February 2002 to June 2005. Most of the site visits corresponded to fall, winter, spring and early summer seasonal conditions.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 161309, DDT (Dichlorodiphenyltrichloroethane)	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

33572

Pollutant:

DDT (Dichlorodiphenyltrichloroethane)

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Zero of 1 sample collected for sum DDT (DDT(o,p') + DDT (p,p')) exceeded the evaluation guideline.

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. Waters shall not contain substances in concentrations that result in deposition of material that causes nuisance or adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for sum of DDT is 62.9 ug/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected at the following station 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

The samples were collected on 10/15/2008.

Environmental Conditions:

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 161309, DDT (Dichlorodiphenyltrichloroethane)	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322159

Pollutant:

DDT (Dichlorodiphenyltrichloroethane)

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. There shall be no bioaccumulation of pesticide concentrations found in bottom sediments or aquatic life. (Water Quality Control Plan for the North Coast Region)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The evaluation guideline for the sum of DDT is the probable effect concentration (PEC) of 62.9 ug/kg dry weight (MacDonald et al., 2000a).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2017-09-20

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

Line of Evidence (LOE) for Decision ID 161309, DDT (Dichlorodiphenyltrichloroethane)	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322354

Pollutant:

Total DDT (sum of 4,4'- and 2,4'- isomers of DDT, DDE, and DDD)

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. There shall be no bioaccumulation of pesticide concentrations found in bottom sediments or aquatic life. (Water Quality Control Plan for the North Coast Region)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The evaluation guideline for total DDTs is the probable effect concentration (PEC) of 572 ug/kg dry weight (MacDonald et al., 2000a).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2017-09-20

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008


DECISION ID	165738	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Dacthal
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165738, Dacthal	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122349

Pollutant:

Dacthal

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Dacthal, Total. Ten sample results were not used in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. USEPA's Lifetime Health advisory level for Dacthal is 0.07 mg/L as stated on page 3 of the 2011 edition of the drinking water standards and health advisories.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Objective/Criterion Reference:

2011 Edition of the Drinking Water Standards and Health Advisories

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	157228	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Deltamethrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 157228, Deltamethrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43593

Pollutant:

Deltamethrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for deltamethrin is the median lethal concentration (LC50) of 0.79 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.79 ug/g is the geometric mean of LC50 values for deltamethrin from Amweg et al. (2005).

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157228, Deltamethrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43594

Pollutant:

Deltamethrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157228, Deltamethrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322171

Pollutant:

Deltamethrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. There shall be no bioaccumulation of pesticide concentrations found in bottom sediments or aquatic life. (Water Quality Control Plan for the North Coast Region)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2017-09-20

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008


DECISION ID	103400	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Demeton
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line(s) of evidence are necessary to assess listing status. One line of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None samples exceeded the objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

Line of Evidence (LOE) for Decision ID 103400, Demeton	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122457

Pollutant:

Demeton

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Demeton-s, Total. Ten samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	157212	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Diazinon
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 157212, Diazinon	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43566

Pollutant:

Diazinon

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for diazinon is the median lethal concentration (LC50) of 11 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 11 ug/g is the geometric mean of LC50 values for diazinon from Ding et al. (2011).

Guideline Reference:

Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157212, Diazinon	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322184

Pollutant:

Diazinon

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. There shall be no bioaccumulation of pesticide concentrations found in bottom sediments or aquatic life. (Water Quality Control Plan for the North Coast Region)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2017-09-20

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 157212, Diazinon	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43567

Pollutant:

Diazinon

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	165750	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Dichlofenthion
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165750, Dichlofenthion	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122458

Pollutant:

Dichlofenthion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Dichlofenthion, Total. Twenty samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	157213	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Dieldrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 157213, Dieldrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122470

Pollutant:

Dieldrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Dieldrin, Total. Ten sample results were not used in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. The established numeric criteria for dieldrin to protect human health from the consumption of water and organisms is 0.00014 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Objective/Criterion Reference:

Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 157213, Dieldrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43661

Pollutant:

Dieldrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for dieldrin is 61.8 ug/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN ]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157213, Dieldrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43677

Pollutant:

Dieldrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for dieldrin is 61.8 ug/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN ]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157213, Dieldrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322195

Pollutant:

Dieldrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. There shall be no bioaccumulation of pesticide concentrations found in bottom sediments or aquatic life. (Water Quality Control Plan for the North Coast Region)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The evaluation guideline for dieldrin is the probable effect concentration (PEC) of 61.8 ug/kg dry weight (MacDonald et al., 2000a).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2017-09-20

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008


DECISION ID	104161	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Dimethoate
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line(s) of evidence are necessary to assess listing status. One lines of evidence is available in the administrative record to assess this pollutant. None of the samples exceed the objectives. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None of the samples exceeded the objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to Section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

Line of Evidence (LOE) for Decision ID 104161, Dimethoate	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122471

Pollutant:

Dimethoate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Dimethoate, Total. Ten samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	157214	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Endrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 157214, Endrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43741

Pollutant:

Endrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for endrin is 207 ug/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN ]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157214, Endrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43742

Pollutant:

Endrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for endrin is 207 ug/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN ]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157214, Endrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322207

Pollutant:

Endrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. There shall be no bioaccumulation of pesticide concentrations found in bottom sediments or aquatic life. (Water Quality Control Plan for the North Coast Region)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The evaluation guideline for endrin is the probable effect concentration (PEC) of 207 ug/kg dry weight (MacDonald et al., 2000a).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2017-09-20

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008


DECISION ID	104607	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Endrin Ketone
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the objective for the MUN beneficial use(s). Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None of the samples exceed the objective for the MUN beneficial use(s) and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

Line of Evidence (LOE) for Decision ID 104607, Endrin Ketone	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122472

Pollutant:

Endrin Ketone

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 20 samples exceed the criterion for Endrin Ketone, Total. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. The established numeric criteria for endrin to protect of human health from the consumption of water and organisms is 0.76 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	157232	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Esfenvalerate/Fenvalerate
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 157232, Esfenvalerate/Fenvalerate	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43614

Pollutant:

Esfenvalerate/Fenvalerate

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for esfenvalerate/fenvalerate is the median lethal concentration (LC50) of 1.5 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 1.5 ug/g is the geometric mean of LC50 values for esfenvalerate/fenvalerate from Amweg et al. (2005).

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157232, Esfenvalerate/Fenvalerate	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43615

Pollutant:

Esfenvalerate/Fenvalerate

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157232, Esfenvalerate/Fenvalerate	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322220

Pollutant:

Esfenvalerate/Fenvalerate

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. There shall be no bioaccumulation of pesticide concentrations found in bottom sediments or aquatic life. (Water Quality Control Plan for the North Coast Region)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2015-10-13

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008


DECISION ID	165751	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Ethion
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165751, Ethion	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122483

Pollutant:

Ethion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Ethion, Total. Ten samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	165752	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Ethoprop
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165752, Ethoprop	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122484

Pollutant:

Ethoprop

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Ethoprop, Total. Ten samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	165753	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Famphur
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165753, Famphur	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122485

Pollutant:

Famphur

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Famphur , Total. Ten samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	165754	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Fenchlorphos
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165754, Fenchlorphos	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122497

Pollutant:

Fenchlorphos

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Fenchlorphos, Total. Ten samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	165755	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Fenitrothion
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165755, Fenitrothion	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122498

Pollutant:

Fenitrothion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Fenitrothion, Total. Ten samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	157231	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Fenpropathrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 157231, Fenpropathrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43996

Pollutant:

Fenpropathrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for fenpropathrin is the median lethal concentration (LC50) of 1 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 1 ug/g is the geometric mean of LC50 values for fenpropathrin from Ding et al. ( 2011).

Guideline Reference:

Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157231, Fenpropathrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322226

Pollutant:

Fenpropathrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. There shall be no bioaccumulation of pesticide concentrations found in bottom sediments or aquatic life. (Water Quality Control Plan for the North Coast Region)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2017-09-20

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 157231, Fenpropathrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43997

Pollutant:

Fenpropathrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	165756	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Fensulfothion
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165756, Fensulfothion	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122499

Pollutant:

Fensulfothion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Fensulfothion, Total. Ten samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	103355	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Fenthion
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line(s) of evidence are necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None samples exceed the objectives. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None of the samples exceeded the objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to Section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

Line of Evidence (LOE) for Decision ID 103355, Fenthion	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122510

Pollutant:

Fenthion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Fenthion, Total. Ten samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	165757	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Heptachlor epoxide
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165757, Heptachlor epoxide	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122511

Pollutant:

Heptachlor epoxide

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Heptachlor Epoxide, Total. Twenty sample results were not used in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to (1) update the numeric objective, and (2) evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. The established numeric criteria for heptachlor to protect of human health from the consumption of water and organisms is 0.00021 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Objective/Criterion Reference:

Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	157215	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Lead
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 157215, Lead	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322258

Pollutant:

Lead

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The evaluation guideline for lead is the probable effect concentration (PEC) of 128 mg/kg dry weight (MacDonald et al., 2000a).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2020-08-26

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

Line of Evidence (LOE) for Decision ID 157215, Lead	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122512

Pollutant:

Lead

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for Lead, Total. This LOE re-assesses data from LOE 21528 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other metals data.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): Waters designated for MUN shall not contain concentrations of chemical constituents in excess of values listed in Table 3-2 of the Basin Plan. The value for lead is 0.05 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):


DECISION ID	165758	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Leptophos
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165758, Leptophos	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122523

Pollutant:

Leptophos

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Leptophos, Total. Ten samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	157216	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 157216, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43485

Pollutant:

Lindane/gamma Hexachlorocyclohexane (gamma-HCH)

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for Lindane (gamma-HCH) is 4.99 ug/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN ]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157216, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43641

Pollutant:

Lindane/gamma Hexachlorocyclohexane (gamma-HCH)

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for Lindane (gamma-HCH) is 4.99 ug/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN ]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157216, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322244

Pollutant:

Lindane/gamma Hexachlorocyclohexane (gamma-HCH)

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP Stream Pollution Trends data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and the results are as follows: 0 of the 1 samples exceeded the evaluation guideline for HCH, gamma-. Although a total of 4 samples were collected, 3 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. There shall be no bioaccumulation of pesticide concentrations found in bottom sediments or aquatic life. (Water Quality Control Plan for the North Coast Region)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The evaluation guideline for lindane is the probable effect concentration (PEC) for Lindane is 4.99 ug/kg dry weight (MacDonald et al., 2000a).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2013-09-25

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):


DECISION ID	161346	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Mercury
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 161346, Mercury	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43769

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for mercury is 1.06 mg/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN ]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 161346, Mercury	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43785

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for mercury is 1.06 mg/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN ]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 161346, Mercury	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122524

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 14 samples exceed the criterion for Mercury, Total. This LOE re-assesses data from LOE 21528 from the 2010 Integrated Report. Data were re-assessed in order to (1) update the numeric objective, and (2) evaluate these data in their own LOE, instead of being evaluated in the same LOE as other metals data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. The established numeric criteria for mercury to protect of human health from the consumption of water and organisms is 0.050 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Objective/Criterion Reference:

Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 161346, Mercury	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322272

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The evaluation guideline for mercury is the probable effect concentration (PEC) of 1.06 mg/kg dry weight (MacDonald et al., 2000a).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2020-08-26

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008


DECISION ID	165759	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Merphos
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165759, Merphos	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122525

Pollutant:

Merphos

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Merphos, Total. Ten samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	104319	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Methidathion
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence are available in the administrative record to assess this pollutant. None of the 20 samples exceed the objective for the MUN beneficial use(s). Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None of the 20 samples exceed the objective for the MUN beneficial use(s) and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

Line of Evidence (LOE) for Decision ID 104319, Methidathion	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122537

Pollutant:

Methidathion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 20 samples exceed the criterion for Methidathion, Total. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): Waters designated for use as domestic or municipal supply (MUN) shall not contain concentrations of chemical constituents in excess of the limits specified in California Code of Regulations, Title 22, Chapter 15. The maximum contaminant level listed in Table 64444-A for methoxychlor is 0.03 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	157217	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Methyl Parathion
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 157217, Methyl Parathion	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

44085

Pollutant:

Methyl Parathion

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for methyl parathion is the median lethal concentration (LC50) of 6 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 6 ug/g is the geometric mean of LC50 values for methyl parathion from Ding et al. (2011).

Guideline Reference:

Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157217, Methyl Parathion	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

44067

Pollutant:

Methyl Parathion

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157217, Methyl Parathion	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322299

Pollutant:

Methyl Parathion

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. There shall be no bioaccumulation of pesticide concentrations found in bottom sediments or aquatic life. (Water Quality Control Plan for the North Coast Region)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2015-10-13

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008


DECISION ID	165760	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Mevinphos
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165760, Mevinphos	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122538

Pollutant:

Mevinphos

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Mevinphos, Total. Ten samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	165761	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Molinate
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165761, Molinate	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122539

Pollutant:

Molinate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Molinate, Total. Ten sample results were not used in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): Waters designated for use as domestic or municipal supply (MUN) shall not contain concentrations of chemical constituents in excess of the limits specified in California Code of Regulations, Title 22, Chapter 15. The maximum contaminant level listed in Table 64444-A for molinate is 0.02 mg/L

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	165762	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Naled
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165762, Naled	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122550

Pollutant:

Naled

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Naled, Total. Ten samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	157218	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Nickel
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal from the CWA section 303(d) List under section 4.1 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. Seven lines of evidence are available in the administrative record to assess pollutant. Zero of 36 samples exceed the Municipal & Domestic Supply beneficial use objective for the total fraction of water. Six of seven samples exceed the Cold Freshwater Habitat objective for the total fraction of sediment, but there is insufficient toxicity data to determine an impairment. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of 36 samples exceed the Municipal & Domestic Supply beneficial use objective for the total fraction of water and this exceeds the allowable frequency listed in Table 4.1 of the Listing Policy. 4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 157218, Nickel	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43669

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for nickel is 48.6 mg/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN ]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157218, Nickel	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43670

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for nickel is 48.6 mg/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN ]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157218, Nickel	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122551

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for Nickel, Total. This LOE re-assesses data from LOE 21528 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other metals data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): Waters designated for use as domestic or municipal supply (MUN) shall not contain concentrations of chemical constituents in excess of the limits specified in California Code of Regulations, Title 22, Chapter 15. The maximum contaminant level listed in Table 64431-A for nickel is 0.1 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 157218, Nickel	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

46850

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Zero of fifteen samples exceeded the nickel objective. This LOE re-assesses data from LOE 21528 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other metals data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): Waters designated for use as domestic or municipal supply (MUN) shall not contain concentrations of chemical constituents in excess of the limits specified in California Code of Regulations, Title 22, Chapter 15. The maximum contaminant level listed in Table 64431-A for nickel is 0.1 mg/L.

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected from the Lower Mainstem Eel River at Holmes (SWAMP Station ID 111EELHOL). Samples were collected from well-mixed flows in glides or riffles.

Temporal Representation:

Samples were collected from 15 site visits from February 2002 to June 2005. Most of the site visits corresponded to fall, winter, spring and early summer seasonal conditions.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 157218, Nickel	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

46848

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Zero of 6 samples exceeded the nickel objective. This LOE re-assesses data from LOE 25250 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other metals data.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): Waters designated for use as domestic or municipal supply (MUN) shall not contain concentrations of chemical constituents in excess of the limits specified in California Code of Regulations, Title 22, Chapter 15. The maximum contaminant level listed in Table 64431-A for nickel is 0.1 mg/L.

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected by the Wiyot Tribe at McNulty Slough. The site is on the seaward side of the tide gate located just south of McNulty Lane, adjacent to the old Wiyot Rancheria.

Temporal Representation:

Samples were collected as grab samples on May 4, August 19, and December 2, 2005, and on March 17, July 20, and November 3, 2006.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Samples were collected according to Wiyot Tribes "Draft Quality Assurance Program Plan (QAPP) for Water Quality Assessment and Monitoring" (McKernan et al. 2004).

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 157218, Nickel	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

32082

Pollutant:

Toxicity

LOE Subgroup:

Toxicity

Matrix:

Sediment

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

TOXICITY TESTING

Data Used to Assess Water Quality:

One sample was collected to evaluate sediment toxicity. Growth and/or survival of Hyalella azteca was examined between the sediment field sample and a sediment control, utilizing a 10-day toxicity test. The sample did not exhibit significant toxicity.

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Toxicity is defined as a statistically significant effect in the sample exposure compared to the control using EPA-recommended hypothesis testing. For SWAMP data exceedances are counted with the significant effect code SL. SL is defined as the result being significant compared to the negative control based on a statistical test, less than stated the alpha level, AND less than the evaluation threshold.

Guideline Reference:

Methods for Measuring the Toxicity and Bioaccumulation of Sediment-associated Contaminants with Freshwater Invertebrates, Second Edition. U.S. Environmental Protection Agency Office of Research and Development, Duluth, MI , U.S. Environmental Protection Agency Office of Water, Washington, DC EPA-600/R-99/064

Spatial Representation:

The sample was collected at station 111EELFRN, Eel River at Fernbridge.

Temporal Representation:

The sample was collected in October 15, 2008.

Environmental Conditions:

QAPP Information:

All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157218, Nickel	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322281

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The evaluation guideline for nickel is the probable effect concentration (PEC) of 48.6 mg/kg dry weight (MacDonald et al., 2000a).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2020-08-26

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for DFW_ABL_Monitoring.


DECISION ID	79134	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Nitrogen, Nitrite
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2016)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Pollutant name changed from "Nitrite as Nitrite NO2" to "Nitrogen, Nitrite" "This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line(s) of evidence are necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None of the one samples exceeded the objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met."

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

Line of Evidence (LOE) for Decision ID 79134, Nitrogen, Nitrite	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

105965

Pollutant:

Nitrogen, Nitrite

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2018): Waters designated for use as domestic or municipal supply (MUN) shall not contain concentrations of chemical constituents in excess of the limits specified in California Code of Regulations, Title 22, Chapter 15. The maximum contaminant level listed in Table 64431-A for Nitrite as N is 1.0 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s) (111CR1012)

Temporal Representation:

The samples were collected between the dates of 2014-08-18 and 2014-08-18

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program

Line of Evidence (LOE) for Decision ID 79134, Nitrogen, Nitrite	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

44006

Pollutant:

Nitrite as Nitrite NO2

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): Waters designated for use as domestic or municipal supply (MUN) shall not contain concentrations of chemical constituents in excess of the limits specified in California Code of Regulations, Title 22, Chapter 15. The maximum contaminant level listed in Table 64431-A for Nitrite as N is 1.0 mg/L.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Larabee Creek - 111PS0013 ]

Temporal Representation:

Data was collected on a single day 8/19/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	165763	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Oxadiazon
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165763, Oxadiazon	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122552

Pollutant:

Oxadiazon

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Oxadiazon, Total. Ten samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	165764	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Oxychlordane
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165764, Oxychlordane	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122360

Pollutant:

Oxychlordane

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Oxychlordane, Total. Ten samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	157219	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	PCBs (Polychlorinated biphenyls)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Zero samples exceeded the objectives, guidelines, or criteria for beneficial uses applicable to this water segment-pollutant combination, which is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for toxicants (Table 3.1 of the Listing Policy). The data used satisfies the data quality requirements (section 6.1.4) and data quantity requirements (section 6.1.5) of the Listing Policy. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 157219, PCBs (Polychlorinated biphenyls)	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

25468

Pollutant:

PCBs (Polychlorinated biphenyls)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

500

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

None of the 500 polychlorinated biphenyl (PCB) analytes collected in the lower mainstem Eel River watershed exceed the evaluation guideline. Each of the 10 samples were analyzed for 50 PCB cogeners. The samples were collected as part of the Surface Water Ambient Water Monitoring Program (SWAMP). The data are found in the 5-Year Monitoring Report (NCRWQCB 2008).

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Per the Basin Plan (NCRWQCB 2007, p. 3-4.00): All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - North Coast Region (Region 1)

Evaluation Guideline:

Per the "Public Health Goal for Water Soluble Polychlorinated Biphenyls Expected to Found in Drinking Water" (OEHHA 2007): The health-protective concentration of water-soluble PCBs in
drinking water associated with a one in one million extra lifetime cancer risk is 0.09 ug/L.

Guideline Reference:

Public Health Goal for Water Soluble Polychlorinated Biphenyls Expected to Be Found in Drinking Water. Pesticide and Environmental Toxicology Branch, Office of Environmental Health Hazard Assessment, California Environmental Protection Agency

Spatial Representation:

Samples were collected from the Lower Mainstem Eel River at Holmes (SWAMP Station ID 111EELHOL). Samples were collected from well-mixed flows in glides or riffles.

Temporal Representation:

Samples were collected from 14 site visits from February 2002 to June 2005. Most of the site visits corresponded to fall, winter, spring and early summer seasonal conditions.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 157219, PCBs (Polychlorinated biphenyls)	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322314

Pollutant:

PCBs (Polychlorinated biphenyls)

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The evaluation guideline for total PCBs is the probable effect concentration (PEC) of 676 ug/kg dry weight (MacDonald et al., 2000a).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2017-09-20

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 157219, PCBs (Polychlorinated biphenyls)	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

32999

Pollutant:

PCBs (Polychlorinated biphenyls)

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Zero of 1 sample collected for Total PCBs exceeded the evaluation guideline.

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. Waters shall not contain substances in concentrations that result in deposition of material that causes nuisance or adversely affect beneficial uses(NCRWQCB 2007).

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for total PCB is 676 ug/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected at the following station 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

The samples were collected on 10/15/2008.

Environmental Conditions:

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	157233	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Permethrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 157233, Permethrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43792

Pollutant:

Permethrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for permethrin is the median lethal concentration (LC50) of 8.9 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 8.9 ug/g is the geometric mean of LC50 values for permethrin from Amweg et al. (2005).

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157233, Permethrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322326

Pollutant:

Permethrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. There shall be no bioaccumulation of pesticide concentrations found in bottom sediments or aquatic life. (Water Quality Control Plan for the North Coast Region)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2017-09-20

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 157233, Permethrin	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43793

Pollutant:

Permethrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	165765	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Phorate
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165765, Phorate	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122362

Pollutant:

Phorate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Phorate, Total. Ten samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	165766	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Phosmet
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165766, Phosmet	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122373

Pollutant:

Phosmet

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Phosmet, Total. Twenty sample results were not used in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy. Twenty samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	165767	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Prometon (Prometone)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165767, Prometon (Prometone)	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122374

Pollutant:

Prometon (Prometone)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Prometon, Total. Fourteen sample results were not used in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

According to the 2006 USEPA Drinking Water Standards and Health Advisories, the Life-time Exposure Health Advisory for Prometon (Prometone) is 0.1 mg/L. (EPA 822-R-06-013, 2006)

Guideline Reference:

2006 edition of the drinking water standards and health advisories. EPA 822-R-03-013

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 6/9/2002-4/25/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	165768	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Propazine
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165768, Propazine	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122375

Pollutant:

Propazine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Propazine, Total. Seven sample results were not used in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

According to the 2006 USEPA Drinking Water Standards and Health Advisories, the Life-time Exposure Health Advisory for Propazine is 0.1 mg/L. (EPA 822-R-06-013, 2006)

Guideline Reference:

2006 edition of the drinking water standards and health advisories. EPA 822-R-03-013

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 6/9/2002-4/25/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	157223	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Pyrethroids
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 157223, Pyrethroids	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322343

Pollutant:

Pyrethroids

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The evaluation guideline for the protection of aquatic life from pyrethroids is one toxic unit. Individual pyrethroid concentrations in sediment were normalized to organic carbon content, divided by the respective LC50 and then summed. A sum over over one toxic unit is an exceedance of the evaluation guideline (Amweg et al. 2006).

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Guideline Reference:

Partitioning, bioavailability, and toxicity of the pyrethroid insecticide cypermethrin in sediments. Environmental Toxicology and Chemistry 21:9-15

Guideline Reference:

Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.

Guideline Reference:

Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.

Guideline Reference:

Compilation of freshwater OC-normalized sediment toxicity data for pyrethroids

Guideline Reference:

Pyrethroid insecticides and sediment toxicity in urban creeks from California and Tennessee. Environmental Science and Technology, 40(5): 1700-1706

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2018-09-12

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008


DECISION ID	165769	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Secbumeton
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165769, Secbumeton	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122386

Pollutant:

Secbumeton

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Secbumeton, Total. Seven samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 6/9/2002-4/25/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	104341	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Selenium
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line(s) of evidence are necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the 15 samples exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None of the 15 samples exceeded the objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

Line of Evidence (LOE) for Decision ID 104341, Selenium	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122387

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for Selenium, Total. This LOE re-assesses data from LOE 21528 from the 2010 Integrated Report. Data were re-assessed in order to (1) update the numeric objective, and (2) evaluate these data in their own LOE, instead of being evaluated in the same LOE as other metals data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): Waters designated for use as domestic or municipal supply (MUN) shall not contain concentrations of chemical constituents in excess of the limits specified in California Code of Regulations, Title 22, Chapter 15. The maximum contaminant level listed in Table 64431-A for selenium is 0.05 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	104852	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Silver
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	"This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line(s) of evidence are necessary to assess listing status. One lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None of the fifteen samples exceeded the objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met."

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

Line of Evidence (LOE) for Decision ID 104852, Silver	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122388

Pollutant:

Silver

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for Silver, Total. This LOE re-assesses data from LOE 21528 from the 2010 Integrated Report. Data were re-assessed in order to (1) update the numeric objective, and (2) evaluate these data in their own LOE, instead of being evaluated in the same LOE as other metals data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Objective/Criterion Reference:

Secondary Maximum Contaminant Levels and Compliance. CCR Title 22 section 64449.

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	165770	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Simazine
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165770, Simazine	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122389

Pollutant:

Simazine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Simazine, Total. Seven sample results were not used in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): Waters designated for use as domestic or municipal supply (MUN) shall not contain concentrations of chemical constituents in excess of the limits specified in California Code of Regulations, Title 22, Chapter 15. The maximum contaminant level listed in Table 64444-A for simazine is 0.004 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 6/9/2002-4/25/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	165771	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Simetryn
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165771, Simetryn	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122400

Pollutant:

Simetryn

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Simetryn, Total. Seven sample results were not used in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy. Seven samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 6/9/2002-4/25/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	158430	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Sodium
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 158430, Sodium	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

329091

Pollutant:

Sodium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Per the Drinking Water Standards and Health Advisories (USEPA 2012), the health advisory for sodium for individuals on a sodium-restricted diet is 20 mg/l.

Guideline Reference:

2012 Edition of the Drinking Water Standards and Health Advisories

Spatial Representation:

The samples were collected at 1 monitoring site: NARS_WQX-CARM-1012 (Eel River).

Temporal Representation:

The samples were collected between the dates of 2014-08-18 and 2014-08-18

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

WQX from the NWQMP for the 2026 Integrated Report in Region 1

Line of Evidence (LOE) for Decision ID 158430, Sodium	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

329135

Pollutant:

Sodium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Agricultural Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Water Quality for Agriculture, published by the Food and Agriculture Organization of the United Nations in 1985, contains criteria protective of various agricultural uses of water, including irrigation of various types of crops and stock watering. At or below the sodium threshold of 69 mg/L, agricultural uses of water should not be limited.

Guideline Reference:

Water Quality for Agriculture, Food and Agriculture Organization of the United Nations - Irrigation and Drainage Paper No. 29, Rev 1, Rome (1985)

Spatial Representation:

The samples were collected at 1 monitoring site: NARS_WQX-CARM-1012 (Eel River).

Temporal Representation:

The samples were collected between the dates of 2014-08-18 and 2014-08-18

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for DFW_ABL_Monitoring.

Line of Evidence (LOE) for Decision ID 158430, Sodium	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

112633

Pollutant:

Sodium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Agricultural Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Water Quality for Agriculture, Food and Agriculture Organization of the United Nations - Irrigation and Drainage Paper No. 29, Rev 1, Rome (1985)

Spatial Representation:

The samples were collected at 1 monitoring site(s) (111CR1012)

Temporal Representation:

The samples were collected between the dates of 2014-08-18 and 2014-08-18

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program

Line of Evidence (LOE) for Decision ID 158430, Sodium	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

105707

Pollutant:

Sodium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for DFW_ABL_Monitoring.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Per the Drinking Water Standards and Health Advisories (USEPA 2012), the health advisory for sodium for individuals on a sodium-restricted diet is 20 mg/l.

Guideline Reference:

2012 Edition of the Drinking Water Standards and Health Advisories

Spatial Representation:

The samples were collected at 1 monitoring site(s) (111CR1012)

Temporal Representation:

The samples were collected between the dates of 2014-08-18 and 2014-08-18

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program


DECISION ID	163001	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Specific Conductivity
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available. ***COLD FRESHWATER HABITAT BENEFICIAL USE: EEL RIVER has six lines of evidence (LOEs 318030, 318769, 318830, 318834, 318838, 318842) and 11 of 13 samples exceed the guideline, which exceeds the allowable frequency in Table 3.2 of the Listing Policy; however, 8 of 9 samples were collected in saline water. LARABEE CREEK has one line of evidence (LOE 318243) and 0 of 1 sample exceeds the guideline. MCNULTY SLOUGH has one line of evidence (LOE 318905) and 0 of 3 samples exceed the guideline.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:	***COLD FRESHWATER HABITAT BENEFICIAL USE: EEL RIVER has six lines of evidence (LOEs 318030, 318769, 318830, 318834, 318838, 318842) and 11 of 13 samples exceed the guideline, which exceeds the allowable frequency in Table 3.2 of the Listing Policy; however, 8 of 9 samples were collected in saline water. LARABEE CREEK has one line of evidence (LOE 318243) and 0 of 1 sample exceeds the guideline. MCNULTY SLOUGH has one line of evidence (LOE 318905) and 0 of 3 samples exceed the guideline.

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 163001, Specific Conductivity	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318838

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed specific conductivity data for QAPP for Adventure Scientists (Volunteer)* and determined that calendar year 2021 exceeds the 50% upper limit, so that 1 of 1 sample exceeds the water quality objective.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Per the Basin Plan (NCRWQCB 2007): The 90% upper limit specific conductance objective at 77 F is 375 micromhos (or mS/cm2). The 50% upper limit specific conductance objective at 77 F is 225 micromhos (or mS/cm2). The 90% and 50% upper limits represent the 90/50 percentile values for a calendar year. 90% or 50% or more of the values must be less than or equal to the upper limit.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

This sample was collected at sampling station name: Eel Wild and Scenic River-40.58.124.15; station code: ADVENTURESCIENTISTS-40.58.124.15.

Temporal Representation:

This sample was collected on 6/24/2021.

Environmental Conditions:

QAPP Information:

QAPP for Adventure Scientists (Volunteer)*

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 163001, Specific Conductivity	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318905

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed specific conductivity data for Wiyot Tribe, California (Tribal) and determined that calendar years 2010, 2011, and 2012 do not exceed either the 90% or 50% upper limit, so that 0 of 3 samples exceed the water quality objective.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

These samples were collected at sampling station name: McNulty Slough; station code: WIYOT_WQX-MNS-1.

Temporal Representation:

These samples were collected from 9/2/2010-2/23/2012.

Environmental Conditions:

QAPP Information:

QAPP for Wiyot Tribe, California (Tribal)

QAPP Information Reference(s):

Data collected by a California Tribe QAPP Approved by U.S. EPA QAPP Reference

Line of Evidence (LOE) for Decision ID 163001, Specific Conductivity	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

44469

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Secondary Maximum Contaminant Levels and Compliance. CCR Title 22 section 64449.

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Larabee Creek - 111PS0013]

Temporal Representation:

Data was collected on a single day 8/19/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 163001, Specific Conductivity	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

21301

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

None of the 14 specific conductivity grab samples collected from the Lower Mainstem Eel River exceed the objective. The samples were collected as part of the Surface Water Ambient Water Monitoring Program (SWAMP). The data are found in the SWAMP Summary Report for the North Coast Region for Years 2000-2006 (NCRWQCB 2008).

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - North Coast Region (Region 1)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected from the Lower Mainstem Eel River at Holmes (SWAMP Station ID 111EELHOL). Samples were collected from well-mixed flows in glides or riffles.

Temporal Representation:

Samples were collected from 14 site visits from February 2002 to June 2005. Most of the site visits corresponded to fall, winter, spring and early summer seasonal conditions.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (Puckett 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 163001, Specific Conductivity	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

100798

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed the data for this water body to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality standard for specific conductance. Data range from 270 microhmos.

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for DFW_ABL_Monitoring.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Basin, Chapter III, General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states the following: Specific conductivity shall conform to Table 3-1 which states that water quality objective for specific conductivity has an 90% upper limit of 375 micromhus and a 50% upper limit of 225 micromhos.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s) Eel River -1012
(111CR1012)

Temporal Representation:

The samples were collected between the dates 08/18/2014.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program

Line of Evidence (LOE) for Decision ID 163001, Specific Conductivity	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318769

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed specific conductivity data for EPA National Aquatic Resources Survey (NARS) and determined that calendar year 2014 exceeds the 50% upper limit, so that 1 of 1 sample exceeds the water quality objective.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

These samples were collected at sampling station name: Eel River; station code: NARS_WQX-CARM-1012.

Temporal Representation:

These samples were collected from 8/18/2014-8/19/2014.

Environmental Conditions:

QAPP Information:

QAPP for EPA National Aquatic Resources Survey (NARS)

QAPP Information Reference(s):

WQX from the NWQMP for the 2026 Integrated Report in Region 1

Line of Evidence (LOE) for Decision ID 163001, Specific Conductivity	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318834

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed specific conductivity data for Adventure Scientists (Volunteer)* and determined that calendar year 2021 exceeds the 50% upper limit, so that 1 of 1 sample exceeds the water quality objective.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

This sample was collected at sampling station name: Eel Wild and Scenic River-40.47.124.11; station code: ADVENTURESCIENTISTS-40.47.124.11.

Temporal Representation:

This sample was collected on 6/24/2021.

Environmental Conditions:

QAPP Information:

QAPP for Adventure Scientists (Volunteer)*

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 163001, Specific Conductivity	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318830

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

This sample was collected at sampling station name: Eel Wild and Scenic River-40.45.123.99; station code: ADVENTURESCIENTISTS-40.45.123.99.

Temporal Representation:

This sample was collected on 6/4/2021.

Environmental Conditions:

QAPP Information:

QAPP for Adventure Scientists (Volunteer)*

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 163001, Specific Conductivity	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318030

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assess data for parent project SWAMP Stream Pollution Trends and determined calendar years 2013, 2015, 2017, 2019, and 2021 exceed the 90% and 50% upper limits, calendar year 2022 exceeds the 50% upper limit, and calendar year 2020 does not exceed either the 90% or 50% upper limit, so that 6 of 7 samples exceed the water quality objective.

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

These samples were collected at sampling station name: Eel River at Fernbridge; station code: 111EELFRN

Temporal Representation:

These samples were collected from 9/23/2013-9/15/2022

Environmental Conditions:

QAPP Information:

QAPP for SWAMP Stream Pollution Trends

QAPP Information Reference(s):

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

Line of Evidence (LOE) for Decision ID 163001, Specific Conductivity	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318243

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed specific conductivity data for SWAMP Perennial Stream Surveys and determined that 0 of 1 sample for calendar year 2017 exceeds the water quality objective.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

This sample was collected from sampling station name: Larabee Creek ~0.5mi above Frost Creek; station code: 111PS0322.

Temporal Representation:

This sample was collected on 6/20/2017.

Environmental Conditions:

QAPP Information:

QAPP for SWAMP Perennial Stream Surveys

QAPP Information Reference(s):

WQX from the NWQMP for the 2026 Integrated Report in Region 1

Line of Evidence (LOE) for Decision ID 163001, Specific Conductivity	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318842

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed specific conductivity data for Adventure Scientists (Volunteer)* and determined that calendar year 2021 exceeds the 90% and 50% upper limits, so that 1 of 1 sample exceeds the water quality objective.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

This sample was collected at sampling station: Eel Wild and Scenic River-40.64.124.28; station code: ADVENTURESCIENTISTS-40.64.124.28.

Temporal Representation:

This sample was collected on 6/25/2021.

Environmental Conditions:

QAPP Information:

QAPP for Adventure Scientists (Volunteer)*

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638


DECISION ID	158431	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Sulfates
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 158431, Sulfates	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

44052

Pollutant:

Sulfates

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Secondary Maximum Contaminant Levels and Compliance. CCR Title 22 section 64449.

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Larabee Creek - 111PS0013 ]

Temporal Representation:

Data was collected on a single day 8/19/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 158431, Sulfates	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

25541

Pollutant:

Sulfates

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

None of the 15 sulfate samples collected in the Lower Mainstem Eel River watershed exceed the evaluation guideline. The samples were collected as part of the Surface Water Ambient Water Monitoring Program (SWAMP). The data are found in the 5-Year Monitoring Report (NCRWQCB 2008).

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Per the Basin Plan (NCRWQCB 2007, p. 3-3.00): Waters shall not contain taste- or odor-producing substances in concentrations that impart undesirable tastes or odors to fish flesh or other edible products of aquatic origin, or that cause nuisance or adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - North Coast Region (Region 1)

Evaluation Guideline:

Per 22 CCR 64449 (Table 64449-B): The recommended secondary maximum contaminant level for sulfate is 250 mg/L.

Guideline Reference:

Title 22. Division 4. Chapter 15. Sections 64400 et seq. California Code of Regulations

Spatial Representation:

Samples were collected from the Lower Mainstem Eel River at Holmes (SWAMP Station ID 111EELHOL). Samples were collected from well-mixed flows in glides or riffles.

Temporal Representation:

Samples were collected from 15 site visits from February 2002 to June 2005. Most of the site visits corresponded to fall, winter, spring and early summer seasonal conditions.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 158431, Sulfates	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

329231

Pollutant:

Sulfates

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: NARS_WQX-CARM-1012 (Eel River).

Temporal Representation:

The samples were collected between the dates of 2014-08-18 and 2014-08-18

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for DFW_ABL_Monitoring.

Line of Evidence (LOE) for Decision ID 158431, Sulfates	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

118385

Pollutant:

Sulfates

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s) (111CR1012)

Temporal Representation:

The samples were collected between the dates of 2014-08-18 and 2014-08-18

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program


DECISION ID	165772	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Sulfotep
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165772, Sulfotep	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122401

Pollutant:

Sulfotep

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Sulfotep, Total. Ten samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	165774	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Terbufos
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165774, Terbufos	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122410

Pollutant:

Terbufos

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Terbufos, Total. Twenty-four sample results were not used in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

According to the 2006 USEPA Drinking Water Standards and Health Advisories, the Life-time Exposure Health Advisory for Terbufos is 0.0004 mg/L. (EPA 822-R-06-013, 2006)

Guideline Reference:

2006 edition of the drinking water standards and health advisories. EPA 822-R-03-013

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	165775	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Tetrachlorvinphos
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165775, Tetrachlorvinphos	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122411

Pollutant:

Tetrachlorvinphos

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Tetrachlorvinphos, Total. Ten samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	169477	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Thiobencarb
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Zero samples exceeded the objectives, guidelines, or criteria for beneficial uses applicable to this water segment-pollutant combination, which is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for toxicants (Table 3.1 of the Listing Policy). The data used satisfies the data quality requirements (section 6.1.4) and data quantity requirements (section 6.1.5) of the Listing Policy. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 169477, Thiobencarb	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122412

Pollutant:

Thiobencarb/Bolero

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Thiobencarb, Total. Twenty sample results were not used in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to (1) update the numeric objective, and (2) evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Secondary Maximum Contaminant Levels and Compliance. CCR Title 22 section 64449.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	165777	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Tokuthion
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165777, Tokuthion	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122420

Pollutant:

Tokuthion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Tokuthion, Total. Ten samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	158773	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Toxicity
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 158773, Toxicity	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

333447

Pollutant:

Toxicity

LOE Subgroup:

Toxicity

Matrix:

Sediment

Fraction:

None

Beneficial Use:

Estuarine Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

TOXICITY TESTING

Data Used to Assess Water Quality:

1 of the 7 samples collected by SWAMP Stream Pollution Trends for Eel River HU, Lower Eel River HA (includes the Eel River Delta) exhibited toxicity. A sample may have multiple toxicity test results, but will only be counted once. A sample is defined as being collected on the same day and the same location. The following organisms and parameters were utilized for the toxicity tests: Hyalella azteca for Survival, Hyalella azteca for Growth (wt/surv indiv). The following tests exhibited toxicity: Hyalella azteca for Survival on 2010-10-20.

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The sample is toxic when the response of the organisms exposed to the sample is significantly different (worse) than the response of the organisms exposed to the laboratory control based on statistical hypothesis testing. An exceedance is counted when the significant effect code is "Significant; Less Similarity," which means that the sample result is significantly different than the control result, and the percent effect is greater than the evaluation threshold. The default evaluation threshold is 20% unless otherwise stated.

Guideline Reference:

Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms. Fourth Edition. Office of Water, U.S. Environmental Protection Agency. Washington, D.C. EPA-821-R-02-013

Spatial Representation:

The samples were collected at monitoring site: 111EELFRN ( Eel River at Fernbridge ).

Temporal Representation:

The samples were collected between the dates of 2010-10-20 and 2019-09-11.

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

Line of Evidence (LOE) for Decision ID 158773, Toxicity	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

333448

Pollutant:

Toxicity

LOE Subgroup:

Toxicity

Matrix:

Sediment

Fraction:

None

Beneficial Use:

Marine Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

TOXICITY TESTING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at monitoring site: 111EELFRN ( Eel River at Fernbridge ).

Temporal Representation:

The samples were collected between the dates of 2010-10-20 and 2019-09-11.

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

Line of Evidence (LOE) for Decision ID 158773, Toxicity	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

333446

Pollutant:

Toxicity

LOE Subgroup:

Toxicity

Matrix:

Sediment

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

TOXICITY TESTING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at monitoring site: 111EELFRN ( Eel River at Fernbridge ).

Temporal Representation:

The samples were collected between the dates of 2010-10-20 and 2019-09-11.

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008


DECISION ID	165778	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Trichlorfon
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165778, Trichlorfon	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122421

Pollutant:

Trichlorfon

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Trichlorfon, Total. Twenty samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	157221	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Turbidity
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 157221, Turbidity	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

327229

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Waters designated for use as domestic or municipal supply (MUN) shall not contain concentrations of chemical constituents in excess of the limits specified in California Code of Regulations, Title 22, Chapter 15, Division 4, Article 4, Section 64435 (Tables 2 and 3), and Section 64444.5 (Table 5), and listed in Table 3-2 of this Plan (Water Quality Control Plan, North Coast Basin).

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

California Maximum Contaminant Levels (MCLs) apply to ambient surface waters under the Basin Plan's 'Chemical Constituents' objective. The Secondary MCL for turbidity is 5 NTU. Calculation of a numeric objective for other beneficial uses requires comparison with upstream or other background data which may not be available as part of the data used for water quality assessment.

Guideline Reference:

California Code of Regulations, Title 22, Division 4, Chapter 15. Domestic Water Quality and Monitoring

Spatial Representation:

The samples were collected at 1 monitoring site: 111PS0322 (Larabee Creek ~0.5mi above Frost Creek).

Temporal Representation:

The samples were collected between the dates of 2017-06-20 and 2017-06-20

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

WQX from the NWQMP for the 2026 Integrated Report in Region 1

Line of Evidence (LOE) for Decision ID 157221, Turbidity	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

329372

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

California Code of Regulations, Title 22, Division 4, Chapter 15. Domestic Water Quality and Monitoring

Spatial Representation:

The samples were collected at 1 monitoring site: NARS_WQX-CARM-1012 (Eel River).

Temporal Representation:

The samples were collected between the dates of 2014-08-18 and 2014-08-18

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):


DECISION ID	157222	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Zinc
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 157222, Zinc	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43733

Pollutant:

Zinc

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for zinc is 459 mg/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN ]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 157222, Zinc	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

322366

Pollutant:

Zinc

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

The evaluation guideline for zinc is the probable effect concentration (PEC) of 459 mg/kg dry weight (MacDonald et al., 2000a).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 111EELFRN (Eel River at Fernbridge).

Temporal Representation:

Data for this waterbody were collected over the date range 2010-10-20 to 2020-08-26

Environmental Conditions:

QAPP Information:

QAPP for Surface Water Ambient Monitoring Program (SWAMP)

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

Line of Evidence (LOE) for Decision ID 157222, Zinc	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122422

Pollutant:

Zinc

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for Zinc, Total. This LOE re-assesses data from LOE 21528 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other metals data.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Objective/Criterion Reference:

Secondary Maximum Contaminant Levels and Compliance. CCR Title 22 section 64449.

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 157222, Zinc	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43749

Pollutant:

Zinc

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for zinc is 459 mg/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Fernbridge - 111EELFRN ]

Temporal Representation:

Data was collected on a single day 10/15/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	104026	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	alpha.-BHC (Benzenehexachloride or alpha-HCH)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line(s) of evidence are necessary to assess listing status. One line(s) of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None samples exceeded the objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

Line of Evidence (LOE) for Decision ID 104026, alpha.-BHC (Benzenehexachloride or alpha-HCH)	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122337

Pollutant:

alpha.-BHC (Benzenehexachloride or alpha-HCH)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for HCH, alpha-, Total. Thirty-nine sample results were not used in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to (1) update the numeric objective, and (2) evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. The established numeric criteria for alpha-BHC (HCH, alpha) to protect human health from the consumption of water and organisms is 0.0039 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Objective/Criterion Reference:

Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	165779	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	cis-Nonachlor
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165779, cis-Nonachlor	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122347

Pollutant:

cis-Nonachlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Nonachlor, cis-, Total. Twenty samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	165780	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	p,p'-DDMU
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 165780, p,p'-DDMU	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

122361

Pollutant:

p,p'-DDMU

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff re-assessed SWAMP data for Eel River HU, Lower Eel River HA (includes the Eel River Delta) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for DDMU(p,p'), Total. Ten samples were removed from assessment because an appropriate evaluation guideline for the water body-pollutant combination could not be obtained for this listing cycle. This LOE re-assesses data from LOE 29782 from the 2010 Integrated Report. Data were re-assessed in order to evaluate these data in their own LOE, instead of being evaluated in the same LOE as other pesticide data.

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Eel River HU, Lower Eel River HA (includes the Eel River Delta) was collected at 1 monitoring site [ Eel River at Holmes - 111ER1574]

Temporal Representation:

Data was collected over the time period 2/28/2002-6/20/2005.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	155285	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	pH
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Ten lines of evidence are available in the administrative record to assess this pollutant. Six of the 68 samples exceed the Objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Six of 68 samples exceeded the Objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 155285, pH	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318768

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed pH data for EPA National Aquatic Resources Survey (NARS) and determined that 0 samples are less than pH 6.5 and 1 sample is greater than pH 8.5, so that 1 of 2 samples exceed the water quality objective.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Basin, Chapter III, General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states the following: The pH shall conform to the values listed in Table 3-1 which states that the water quality objective for pH shall not be depressed below 6.5 or raised above 8.5.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

These samples were collected at sampling station name: Eel River; station code: NARS_WQX-CARM-1012.

Temporal Representation:

These samples were collected from 8/18/2014-8/19/2014.

Environmental Conditions:

QAPP Information:

QAPP for EPA National Aquatic Resources Survey (NARS)

QAPP Information Reference(s):

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

Line of Evidence (LOE) for Decision ID 155285, pH	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318242

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed pH data for SWAMP Perennial Stream Surveys and determined that 0 samples were less than pH 6.5 and 0 samples were greater than pH 8.5, so that 0 of 1 sample exceeds the water quality objective.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

This sample was collected from sampling station name: Larabee Creek ~0.5mi above Frost Creek; station code: 111PS0322.

Temporal Representation:

This sample was collected on 6/20/2017.

Environmental Conditions:

QAPP Information:

QAPP for SWAMP Perennial Stream Surveys

QAPP Information Reference(s):

WQX from the NWQMP for the 2026 Integrated Report in Region 1

Line of Evidence (LOE) for Decision ID 155285, pH	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318829

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed pH data for Adventure Scientists (Volunteer)* and determined that 0 samples are less than pH 6.5 and 1 sample is greater than pH 8.5, so that 1 of 1 sample exceeds the water quality objective.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

This sample was collected at sampling station name: Eel Wild and Scenic River-40.45.123.99; station code: ADVENTURESCIENTISTS-40.45.123.99.

Temporal Representation:

This sample was collected on 6/4/2021.

Environmental Conditions:

QAPP Information:

QAPP for Adventure Scientists (Volunteer)*

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 155285, pH	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318029

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assess data for parent project SWAMP Stream Pollution Trends and determined that 0 samples are less than pH 6.5 and 0 samples are greater than pH 8.5, so that 0 of 6 samples exceed the water quality objective for pH.

Data Reference:

Field, Habitat, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 1

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

These samples were collected at sampling station name: Eel River at Fernbridge; station code: 111EELFRN

Temporal Representation:

These samples were collected from 9/23/2013-9/15/2022

Environmental Conditions:

QAPP Information:

QAPP for SWAMP Stream Pollution Trends

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 155285, pH	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

33915

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

The sample collected did not exceed the objective.

Data Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Region (NCRWQCB 2011): The pH shall not be depressed below 6.5 nor raised above 8.5.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One sample was collected from the Larabee Creek station (111PS0013).

Temporal Representation:

One sample was collected in August 2008.

Environmental Conditions:

QAPP Information:

SWAMP QAPP

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 155285, pH	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

100809

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed the data for this water body to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality standard for pH. Data range from 8.6.

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for DFW_ABL_Monitoring.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s) Eel River -1012
(111CR1012)

Temporal Representation:

The samples were collected between the dates 08/18/2014.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program

Line of Evidence (LOE) for Decision ID 155285, pH	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318833

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

This sample was collected at sampling station name: Eel Wild and Scenic River-40.47.124.11; station code: ADVENTURESCIENTISTS-40.47.124.11.

Temporal Representation:

This sample was collected on 6/24/2021.

Environmental Conditions:

QAPP Information:

QAPP for Adventure Scientists (Volunteer)*

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 155285, pH	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318841

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed pH data for Adventure Scientists (Volunteer)* and determined that 0 samples are less than pH 6.5 and 0 samples are greater than pH 8.5, so that 0 of 1 sample exceeds the water quality objective.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

This sample was collected at sampling station: Eel Wild and Scenic River-40.64.124.28; station code: ADVENTURESCIENTISTS-40.64.124.28.

Temporal Representation:

This sample was collected on 6/25/2021.

Environmental Conditions:

QAPP Information:

QAPP for Adventure Scientists (Volunteer)*

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 155285, pH	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

318837

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed pH data for QAPP for Adventure Scientists (Volunteer)* and determined that 0 samples are less than pH 6.5 and 1 sample is greater than pH 8.5, so that 1 of 1 sample exceeds the water quality objective.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

This sample was collected at sampling station name: Eel Wild and Scenic River-40.58.124.15; station code: ADVENTURESCIENTISTS-40.58.124.15.

Temporal Representation:

This sample was collected on 6/24/2021.

Environmental Conditions:

QAPP Information:

QAPP for Adventure Scientists (Volunteer)*

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 155285, pH	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

25251

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Aquatic Life Use:

Estuarine Habitat | Fish Migration | Fish Spawning | Preservation of Rare & Endangered Species | Wildlife Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

One of the 53 mean pH values calculated from samples collected in the Eel River Delta exceed the objective. Mean pH concentrations range from 7.11 to 8.54. Samples were collected by the Wiyot Tribe and data are summarized by the Tribe (Wiyot 2007).

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Per the Basin Plan (NCRWQCB 2007): For waters not listed in Table 3-1 and where pH are not prescribed, the pH shall not be depressed below 6.5 nor raised above 8.5.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - North Coast Region (Region 1)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The temperatures samples were collected by the Wiyot Tribe at McNulty Slough. The site is on the seaward side of the tide gate located just south of McNulty Lane, adjacent to the old Wiyot Rancheria.

Temporal Representation:

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Samples were collected according to Wiyot Tribe¿s ¿Draft Quality Assurance Program Plan (QAPP) for Water Quality Assessment and Monitoring¿ (McKernan et al. 2004).

QAPP Information Reference(s):


DECISION ID	168389	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Sediment
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Sources:	A Source Unknown
TMDL Priority:	Low
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Regional Water Board Conclusion: This pollutant was considered for placement on the section 303(d) List in a previous Integrated Report cycle under the pollutant name Sedimentation/Siltation. No new information was reviewed for this current Integrated Report cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for listing under Section 2.2 of the Listing Policy. Under this section of the Policy, a minimum of one line of evidence is needed to assess listing status. The Lower Eel River Total Maximum Daily Loads for Temperature and Sediment were established by US EPA in December 18, 2007. Based on the readily available information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination in the Water Quality Limited Segments Being Addressed portion of the Section 303(d) List. This listing applies to the entire waterbody. This listing applies to the entire waterbody.

Regional Board Decision Recommendation:	This is a decision previously approved by the State Water Resources Control Board and the USEPA as sedimentation/siltation. No new data were assessed by the Regional Board for the current cycle. The decision has not changed.

State Board Review of Regional Board Conclusion and Recommendation:	This listing applies to the entire waterbody.

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 168389, Sediment	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

3660

Pollutant:

Sedimentation/Siltation

LOE Subgroup:

Pollutant-Water

Matrix:

Not Specified

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

This LOE is a placeholder to support a 303(d) listing decision made prior to 2006.

Data Reference:

Placeholder reference pre-2006 303(d)

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Unknown

Temporal Representation:

Unknown

Environmental Conditions:

Unknown

QAPP Information:

Unknown

QAPP Information Reference(s):


DECISION ID	68049	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Sedimentation/Siltation
Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)(2016)
Revision Status	Original
Sources:	A Source Unknown
TMDL Name:	Eel River, Lower Mainstem Sediment & Temperature TMDLs
TMDL Project Code:	1206
Date TMDL Approved by USEPA:	12/18/2007
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Regional Water Board Conclusion: This pollutant was considered for placement on the section 303(d) List in a previous Integrated Report cycle. No new information was reviewed for this current Integrated Report cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for listing under Section 2.2 of the Listing Policy. Under this section of the Policy, a minimum of one line of evidence is needed to assess listing status. The Lower Eel River Total Maximum Daily Loads for Temperature and Sediment were established by US EPA in December 18, 2007. Based on the readily available information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination in the Water Quality Limited Segments Being Addressed portion of the Section 303(d) List.

Regional Board Decision Recommendation:	This is a decision previously approved by the State Water Resources Control Board and the USEPA. No new data were assessed by the Regional Board for the current cycle. The decision has not changed.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

Line of Evidence (LOE) for Decision ID 68049, Sedimentation/Siltation	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

3660

Pollutant:

Sedimentation/Siltation

LOE Subgroup:

Pollutant-Water

Matrix:

Not Specified

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

This LOE is a placeholder to support a 303(d) listing decision made prior to 2006.

Data Reference:

Placeholder reference pre-2006 303(d)

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Unknown

Temporal Representation:

Unknown

Environmental Conditions:

Unknown

QAPP Information:

Unknown

QAPP Information Reference(s):


DECISION ID	74008	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Hexachlorobenzene/ HCB
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2016)
Revision Status	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Regional Board Conclusion: The pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the Section 303(d) List under Section 3.1 of the Listing Policy. Under Section 3.1, a single line of evidence is necessary to assess listing status. One line of evidence is available to assess protection of the municipal and domestic supply (MUN) beneficial use. It should be noted that the pollutant name was changed from Pesticides to Hexachlorobenzene/ HCB, and the DDT data were removed from this decision so they could be assessed in their own decision. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category (i.e., sufficient justification to not list). This conclusion is based on the staff findings that: (1) The data used satisfies the data quality requirements of Section 6.1.4 of the Policy. (2) The data used satisfies the data quantity requirements of Section 6.1.5 of the Policy. (3) One of eight samples exceed the evaluation guideline used to interpret the narrative objective, and this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met, as a minimum of either (A) 16 samples, or (B) greater than or equal 2 exceedances of the objective with less than 16 samples is needed for application of Table 3.1. (4) Pursuant to Section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

Line of Evidence (LOE) for Decision ID 74008, Hexachlorobenzene/ HCB	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

25627

Pollutant:

Hexachlorobenzene/ HCB

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

One of the 8 hexachlorobenzene samples collected in the lower mainstem Eel River exceeds the evaluation guideline. Sample concentrations range from non-detect (with a reporting limit of 0.001 ug/l) to detected but not quantified with a concentration of at least 0.001 ug/l. The samples were collected as part of the Surface Water Ambient Water Monitoring Program (SWAMP). The data are found in the 5-Year Monitoring Report (NCRWQCB 2008).

Data Reference:

Surface Water Ambient Monitoring Program (SWAMP). Summary Report for the North Coast Region (RWQCB-1) for years 2000-2006. North Coast Regional Water Quality Control Board. March 2008

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - North Coast Region (Region 1)

Evaluation Guideline:

Per the National Recommended Water Quality Criteria (USEPA 2006): The recommended criterion for hexachlorobenzene for the protection of source waters for human health consumption of water and organisms is 0.00028 ug/l.

Guideline Reference:

Spatial Representation:

Samples were collected from the Lower Mainstem Eel River at Holmes (SWAMP Station ID 111EELHOL). Samples were collected from well-mixed flows in glides or riffles.

Temporal Representation:

Samples were collected from 14 site visits from February 2002 to June 2005. Most of the site visits corresponded to fall, winter, spring and early summer seasonal conditions.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Quality control was conducted in accordance with the SWAMP Quality Assurance Management Plan (SWAMP 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	170540	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Indicator Bacteria
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	The State Water Board’s Water Quality Control Plan for Inland Surface Waters, Enclosed Bays, and Estuaries of California (the “ISWEBE Plan”) was adopted on August 7, 2018, and contains bacteria water quality objectives applicable to the REC-1 beneficial use. This has resulted in a change from assessing fecal coliform to assessing E. coli in fresh water and Enterococcus in saline water. Fecal coliform lines of evidence used in previous indicator bacteria decisions in the North Coast Region have been retired. In accordance with section 6.1.5.3 of the Listing Policy, data should be representative of the critical timing that the pollutant is expected to impact the waterbody. Lacking constant inputs, indicator bacteria do not persist in the environment for a long period and effects are of relatively short duration. As a result, the historic levels of E. coli in the waterbody may be a poor indicator of current risks to human health, particularly when more recent data are available to sufficiently assess the water quality standard. Historic lines of evidence for data collected prior to October 21, 2012 were evaluated pursuant to these considerations and were not used to assess water quality standards attainment because they do not meet the temporal representation requirements of section 6.1.5.3 of the Listing Policy. No data has been collected from on or after October 21, 2012 and so the existing decision will carry-over. Beneficial use support will be reassessed in a future cycle, if more data are available.

Regional Board Decision Recommendation:	This is a decision previously approved by the State Water Resources Control Board and the USEPA. No new data were assessed by the Regional Board for the current cycle. The decision has not changed.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 170540, Indicator Bacteria	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

23465

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Two of the 6 single fecal coliform samples collected from the Eel River Delta exceed the evaluation guideline. Values range from 17 to 1,600 MPN / 100 ml. Samples were collected by the Wiyot Tribe and data are summarized by the Tribe (Wiyot 2007).

Data Reference:

Staff Report Regarding Russian River Bacterial Water Quality Monitoring in the Vicinity of Fitch Mountain Sonoma County, California. April through September, 1995. North Coast Regional Water Quality Control Board

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Per the Basin Plan (NCRWQCB 2007): The bacteriological quality of waters of the North Coast Region shall not be degraded beyond natural background levels. In no case shall coliform concentrations in waters of the North Coast Region exceed the following: In waters designated for contact recreation (REC-1), the median fecal coliform concentration based on a minimum of not less than 5 samples for any 30-day period shall not exceed 50 MPN* / 100 ml, nor shall more than 10% of total samples during any 30-day period exceed 400 MPN / 100 ml. *Note: MPN is the most probable number of coliform units.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - North Coast Region (Region 1)

Evaluation Guideline:

Per the "Draft Guidance for Fresh Water Beaches" (DHS 2006): Beach posting is recommended when single sample fecal coliform levels exceed 400 MPN / 100 ml.

Guideline Reference:

Draft Guidance for Fresh Water Beaches. Last Update: May 8, 2006. Initial Draft: November 1997. California Department of Public Health.

Spatial Representation:

Samples were collected by the Wiyot Tribe at McNulty Slough. The site is on the seaward side of the tide gate located just south of McNulty Lane, adjacent to the old Wiyot Rancheria.

Temporal Representation:

Samples were collected as grab samples on May 4, August 19, and December 2, 2005, and on March 17, July 20, and November 3, 2006.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Samples were collected according to Wiyot Tribe¿s ¿Draft Quality Assurance Program Plan (QAPP) for Water Quality Assessment and Monitoring¿ (McKernan et al. 2004).

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 170540, Indicator Bacteria	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

24854

Pollutant:

Total Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

None of the 6 single fecal coliform samples collected from the Eel River Delta exceed the evaluation guideline. Values range from 50 to less than 1,600 MPN / 100 ml. Samples were collected by the Wiyot Tribe and data are summarized by the Tribe (Wiyot 2007).

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - North Coast Region (Region 1)

Evaluation Guideline:

Per the "Draft Guidance for Fresh Water Beaches" (DHS 2006): Beach posting is recommended when single sample total coliform levels exceed 10,000 MPN / 100 ml.

Guideline Reference:

Draft Guidance for Fresh Water Beaches. Last Update: May 8, 2006. Initial Draft: November 1997. California Department of Public Health.

Spatial Representation:

Samples were collected by the Wiyot Tribe at McNulty Slough. The site is on the seaward side of the tide gate located just south of McNulty Lane, adjacent to the old Wiyot Rancheria.

Temporal Representation:

Samples were collected as grab samples on May 4, August 19, and December 2, 2005, and on March 17, July 20, and November 3, 2006.

Environmental Conditions:

There are no known environmental conditions (e.g., seasonality, land use practices, fire events, storms, etc.) that are related to these data.

QAPP Information:

Samples were collected according to Wiyot Tribe¿s ¿Draft Quality Assurance Program Plan (QAPP) for Water Quality Assessment and Monitoring¿ (McKernan et al. 2004).

QAPP Information Reference(s):


DECISION ID	79014	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

Pollutant:	Nitrate/Nitrite (Nitrite + Nitrate as N)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2016)
Revision Status	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Regional Board Conclusion: The pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the Section 303(d) List under Section 3.1 of the Listing Policy. Under Section 3.1, a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant in Larabee Creek (LOE 43800). Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the Section 303(d) List in the Water Quality Limited Segments category (i.e., sufficient justification to not list). This conclusion is based on the staff findings that: (1) The data used satisfies the data quality requirements of Section 6.1.4 of the Policy. (2) The data used satisfies the data quantity requirements of Section 6.1.5 of the Policy. (3) Zero of one sample from Larabee Creek exceeds the water quality objective, however this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met, as a minimum of either (a) 16 samples, or (b) greater than or equal to 2 exceedances of the objective with less than 16 samples is needed for application of Table 3.1. (4) Pursuant to Section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	This is a decision previously approved by the State Water Resources Control Board and the USEPA. No new data were assessed by the Regional Board for the current cycle. The decision has not changed.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

Line of Evidence (LOE) for Decision ID 79014, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 1
Eel River HU, Lower Eel River HA (includes the Eel River Delta)

LOE ID:

43800

Pollutant:

Nitrate/Nitrite (Nitrite + Nitrate as N)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference: