Final California 2024 Integrated Report (303(d) List/305(b) Report)

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138270, Copper	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

258867

Pollutant:

Copper

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 San Gabriel River Regional Monitoring Program data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Copper.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC16832 (SGMR16832).

Temporal Representation:

The samples were collected between the dates of 2018-07-10 and 2018-07-10

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138270, Copper	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

259023

Pollutant:

Copper

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC00574 (SGMR00574).

Temporal Representation:

The samples were collected between the dates of 2017-05-03 and 2017-05-03

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138270, Copper	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254179

Pollutant:

Copper

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138270, Copper	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254317

Pollutant:

Copper

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-06-06 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138270, Copper	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

87916

Pollutant:

Copper

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

None of the 72 samples exceeded the hardness adjusted criteria.

Data Reference:

Data for Various Pollutants in Various Water Bodies in Sanitation Districts of Los Angeles County, 2005-2010.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Surface waters shall not contain concentrations of chemical constituents in amounts that adversely affect any designated beneficial use.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

California Toxics Rule (CTR) lists criterion continuous concentrations (4-day average) to protect aquatic life in freshwater. The criterion in freshwater is hardness dependent for each sample and varies based on the ambient hardness during sampling. Section (b)(1) in CTR contains the hardness dependent formula for the metals criterion. If no hardness data were available, a value of 100 mg/L was used.

Guideline 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

Spatial Representation:

Samples were collected from San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam) from three sample stations: SG-R12, SJC-R2 and SG-R2.

Temporal Representation:

Samples were collected monthly from June 2006 through May of 2010.

Environmental Conditions:

QAPP Information:

The Biology Department of the San Jose Creek Water Quality Laboratory is responsible for collecting samples from receiving water stations along the San Gabriel River, Coyote Creek, San Jose Creek, Santa Clara River, and the Rio Hondo River. Data is collected for the Los Angeles Sanitation District NPDES permits. Some standard operating procedures for sampling were submitted, however no QA Project Plan was.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 138270, Copper	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

2455

Pollutant:

Copper

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Numeric data generated from 51 samples taken from 10/14/98 to 1/1/04, none of which exceed the hardness based CCC (LACDPW, 2004c).

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

CTR Dissolved Copper Criterion for continuous concentration (CCC) in water for the protection of aquatic life is expressed as a function of the total hardness of the water body. The aquatic life criteria will vary depending of total hardness reported at the sampling site. The CCC for dissolved copper is the highest concentration to which aquatic life can be exposed for an extended period of time (four days) without deleterious effects. This criterion is linked and applicable for the protection of aquatic life Beneficial Uses.

Objective/Criterion Reference:

Data for Various Pollutants in Various Water Bodies in Sanitation Districts of Los Angeles County, 2005-2010.

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One (1) sampling station sampled from 10/14/98 to 1/1/04.

Temporal Representation:

Samples taken during the wet and dry season from 10/14/98 to 1/1/04 at approximately one to two week intervals.

Environmental Conditions:

QAPP Information:

Evaluation of Analytes and QA/QC Specifications for Monitoring Program (Woodward-Clyde, 1996) Los Angeles County Department of Public Works.

QAPP Information Reference(s):


DECISION ID	138297	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Temperature, water
Final Listing Decision:	Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Reason for Delisting:	Flaws in original listing
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 4.2 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. Six lines of evidence are available in the administrative record to assess this pollutant. Temperature is a fractionless pollutant, with the fractions "none" and "not recorded" equivalent. These Lines of Evidence have been added together and the resulting totals compared to Table 4.2. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification for 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. 192 of 320 samples exceeded the objective for WARM and this exceeds the allowable frequency listed in Table 4.2 of the Listing Policy. However, it cannot be shown at this time that waterbody exceeds the objective of 80 °F as a result of waste discharges, as required by the Basin Plan for the Los Angeles Region. If at a future time it can be shown that the temperature exceedances result from waste discharge, these data will be reevaluated. 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 be removed from the section 303(d) list because the original basis for listing was flawed. It cannot be shown at this time that waterbody exceeds the objective of 80 °F as a result of waste discharges, as required by the Basin Plan for the Los Angeles Region. If at a future time it can be shown that the temperature exceedances result from waste discharge, these data will be reevaluated.

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 138297, Temperature, water	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

87827

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

224

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Numeric data generated from 224 averages of temperature had 81 exceedences.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

At no time shall warm freshwater habitat-designated waters be raised above 80 degrees Fahrenheit as a result of waste discharges.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected from the SJC-R2 and SJC-R12 stations.

Temporal Representation:

Samples were collected approximately once a month from July 2005 to November 2009.

Environmental Conditions:

QAPP Information:

NPDES quality assurance.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 138297, Temperature, water	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255967

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region (page 3-45) states that: For waters designated WARM, water temperature shall not be altered by more than 5 °F above the natural temperature. At no time shall these WARM-designated waters be raised above 80 °F as a result of waste discharges.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-06-06 and 2019-10-10

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138297, Temperature, water	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255965

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2020-01-13

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138297, Temperature, water	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

256005

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2016-09-14 and 2019-12-16

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138297, Temperature, water	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

266983

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC00574 (SGMR00574).

Temporal Representation:

The samples were collected between the dates of 2017-05-03 and 2017-05-03

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138297, Temperature, water	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

267095

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 San Gabriel River Regional Monitoring Program data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Temperature.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC16832 (SGMR16832).

Temporal Representation:

The samples were collected between the dates of 2018-07-10 and 2018-07-10

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):


DECISION ID	138301	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Zinc
Final Listing Decision:	Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Delist from 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Reason for Delisting:	Applicable WQS attained; reason for recovery unspecified
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. 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. 0 of 33, 3 of 58 and 0 of 42 samples exceeded the criteria 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 be removed from the section 303(d) list because applicable water quality standards for the pollutant 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 138301, Zinc	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

2458

Pollutant:

Zinc

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Numeric data generated from 58 samples taken from 11/10/97 to 1/7/05 at one to two-week sampling interval. Three samples exceeded the dissolved zinc Continuous Criterion Concentration (CCC) (LARWQCB, 2006).

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

CTR Dissolved Zinc Criterion for continuous concentration (CCC) in water for the protection of aquatic life is expressed as a function of the total hardness of the water body. The aquatic life criteria will vary depending on total hardness reported at the sampling site. The CCC for dissolved zinc is the highest concentration to which aquatic life can be exposed for an extended period of time (four days) without deleterious effects. This criterion is linked and applicable for the protection of aquatic life Beneficial Uses.

Objective/Criterion Reference:

Data for Various Pollutants in Various Water Bodies in Sanitation Districts of Los Angeles County, 2005-2010.

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Site S14.

Temporal Representation:

Samples collected between 11/10/97 and 1/7/05.

Environmental Conditions:

QAPP Information:

San Gabriel River Metals TMDL monitoring.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 138301, Zinc	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

87836

Pollutant:

Zinc

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

None of the 42 samples exceeded the hardness adjusted criteria.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Surface waters shall not contain concentrations of chemical constituents in amounts that adversely affect any designated beneficial use.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline 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

Spatial Representation:

Samples were collected from San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam) from three sample stations: SG-R12, SJC-R2 and SG-R2.

Temporal Representation:

Samples were collected monthly from June 2006 through May of 2010.

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 138301, Zinc	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

256097

Pollutant:

Zinc

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The dissolved zinc criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is hardness dependent. The criterion when calculated using a default hardness of 100 mg/L is 120 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138301, Zinc	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

252994

Pollutant:

Zinc

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 0 of 17 samples exceeded the water quality threshold for Zinc.

Data Reference:

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2015-12-14 and 2019-12-20

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138301, Zinc	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

268531

Pollutant:

Zinc

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC00574 (SGMR00574).

Temporal Representation:

The samples were collected between the dates of 2017-05-03 and 2017-05-03

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138301, Zinc	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

268487

Pollutant:

Zinc

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC16832 (SGMR16832).

Temporal Representation:

The samples were collected between the dates of 2018-07-10 and 2018-07-10

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138301, Zinc	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

256138

Pollutant:

Zinc

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138301, Zinc	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

256121

Pollutant:

Zinc

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138282	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Lead
Final Listing Decision:	Delist from 303(d) list (being addressed by 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
Reason for Delisting:	Applicable WQS attained; reason for recovery unspecified
TMDL Name:	San Gabriel River Metals (39)
TMDL Project Code:	385
Date TMDL Approved by USEPA:	03/27/2007
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. Two lines of evidence are available in the administrative record to assess this pollutant. 13 of the 203 samples exceeded the criteria. 0 of the 72samples exceeded the criteria. LOE 28719 is a placeholder LOE for a decision not held in the assessment database. It will not be considered because the other data are sufficient for assessment. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification for 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. 13 of 203 and 0 of 72 samples exceeded the criteria and this does not exceed 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 not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be removed from the section 303(d) list because applicable water quality standards for the pollutant 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 138282, Lead	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255113

Pollutant:

Lead

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The dissolved lead criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is hardness dependent. The criterion when calculated using a default hardness of 100 mg/L is 2.5 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2016-09-14 and 2019-12-16

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138282, Lead	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255115

Pollutant:

Lead

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-06-06 and 2019-10-10

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138282, Lead	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

263047

Pollutant:

Lead

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC00574 (SGMR00574).

Temporal Representation:

The samples were collected between the dates of 2017-05-03 and 2017-05-03

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138282, Lead	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

252609

Pollutant:

Lead

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 1 of 15 samples exceeded the water quality threshold for Lead.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2015-12-14 and 2019-12-20

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138282, Lead	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

262985

Pollutant:

Lead

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC16832 (SGMR16832).

Temporal Representation:

The samples were collected between the dates of 2018-07-10 and 2018-07-10

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

Lead 1995-2007 Monitoring Data (MS4 Data) for San Gabriel River Reach 2. Municipal Storm Water and Urban Runoff Discharges within the County of Los Angeles, and the Incorporated Cities therein, Except the City of Long Beach.

Line of Evidence (LOE) for Decision ID 138282, Lead	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

28296

Pollutant:

Lead

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Preservation of Rare & Endangered Species | Wildlife Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Seven of 66 samples exceeded the hardness dependent California Toxics Rule Criterion Continuous Concentration for lead and zero out 100 samples exceeded the hardness dependent Criterion Maximum Concentration. Water quality samples were taken and analyzed for lead in accordance with the Municipal Separate Storm Sewer System (MS4) permit monitoring and testing parameters.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Toxics Rule lists Criterion Continuous Concentrations for lead to protect aquatic life in freshwater. The lead criterion in freshwater is hardness dependent for each sample and varies based on the on the ambient hardness during sampling. Section (b)(1) in CTR contains the hardness dependent formula for metals criteria.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The Los Angeles County Department of Public Works conducted sampling at the mass emission monitoring station S14 located downstream of the San Gabriel River Parkway (Lat: 34.0133815996, Long: -118.063082152).

Temporal Representation:

Composite samples taken in wet- and dry-weather from October 1995 to April 2007.

Environmental Conditions:

QAPP Information:

Data was collected in compliance with the sampling and monitoring procedures detailed in County of Los Angeles MS4 Permit (NPDES No. CAS004001) Monitoring and Reporting Program.

QAPP Information Reference(s):

Monitoring and Reporting Program - CI 6948 for order no. 01-182 NPDES No. CAS004001 Municipal Storm Water and Urban Runoff Discharges within the County of Los Angeles, and the incorporated cities, except the City of Long Beach

Line of Evidence (LOE) for Decision ID 138282, Lead	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

2459

Pollutant:

Lead

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Numeric data generated from 58 samples taken from 11/10/97 to 1/7/05 at one to two-week sampling intervals. Five samples exceeded the dissolved lead continuous criterion concentration (CCC) (LARWQCB, 2006).

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

CTR dissolved lead criterion for continuous concentration (CCC) in water for the protection of aquatic life is expressed as a function of the total hardness of the water body. The aquatic life criteria will vary depending on total hardness reported at the sampling site. The CCC for dissolved lead is the highest concentration to which aquatic life can be exposed for an extended period of time (four days) without deleterious effects. This criterion is linked and applicable for the protection of aquatic life Beneficial Uses.

Objective/Criterion Reference:

Data for Various Pollutants in Various Water Bodies in Sanitation Districts of Los Angeles County, 2005-2010.

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Site S14.

Temporal Representation:

Samples were collected between 11/10/97 and 1/7/05.

Environmental Conditions:

QAPP Information:

San Gabriel River Metals TMDL monitoring.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 138282, Lead	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

87814

Pollutant:

Lead

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

None of the 72 samples exceeded the hardness adjusted criteria.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Surface waters shall not contain concentrations of chemical constituents in amounts that adversely affect any designated beneficial use.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline 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

Spatial Representation:

Samples were collected from San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam) from three sample stations: SG-R12, SJC-R2 and SG-R2.

Temporal Representation:

Samples were collected monthly from June 2006 through May of 2010.

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 138282, Lead	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

28719

Pollutant:

Lead

LOE Subgroup:

Narrative Description Data

Matrix:

Not Specified

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Preservation of Rare & Endangered Species | Wildlife Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

A TMDL has been established for this water segment-pollutant combination. The San Gabriel River MetalsTMDL was established by USEPA on March 26, 2007.

Data Reference:

Staff report and appendix establishing a TMDL for Metals in the San Gabriel River Watershed.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Temporal Representation:

Environmental Conditions:

QAPP Information:

QA information unavailable.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 138282, Lead	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255139

Pollutant:

Lead

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2020-01-13

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138271	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Cyanide
Final Listing Decision:	Do Not Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Sources:	A Source Unknown
Expected TMDL Completion Date:	2021
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. 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. 8 of 20, 0 of 14 and 2 of 6 samples exceeded the criteria 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 be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.

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 138271, Cyanide	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254208

Pollutant:

Cyanide

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The cyanide criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 5.2 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138271, Cyanide	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

252351

Pollutant:

Cyanide

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and the results are as follows: 2 of the 6 samples exceeded the water quality threshold for Cyanide. Although a total of 7 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The cyanide criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 5.2 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (S14).

Temporal Representation:

Data for this waterbody was collected over the date range 2015-12-14 to 2019-11-20

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138271, Cyanide	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254277

Pollutant:

Cyanide

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The cyanide criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 5.2 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138271, Cyanide	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

4805

Pollutant:

Cyanide

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Preservation of Rare & Endangered Species | Wildlife Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Eight of 20 samples exceeded the California Toxics Rule Criterion Continuous Concentration for Cyanide and one of 20 samples exceeded the Criterion Maximum Concentration. Water quality samples were taken and analyzed for Cyanide in accordance with the Municipal Separate Storm Sewer System (MS4) permit monitoring and testing parameters.

Data Reference:

Monitoring Report (MS4 Data) - CI 6948 for order no. 01-182 NPDES No. CAS004001 Municipal Storm Water and Urban Runoff Discharges within the County of Los Angeles, and the Incorporated Cities therein, Except the City of Long Beach

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Toxics Rule lists a Criterion Continuous Concentration of 5.2 ug/L and a Criterion Maximum Concentration of 22 ug/L for Cyanide to protect aquatic life in freshwater.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Temporal Representation:

Grab samples were taken approximately six per year (four wet-weather events and two dry-weather events), from October 2003 through April 2007.

Environmental Conditions:

QAPP Information:

Data was collected in compliance with the sampling and monitoring procedures detailed in County of Los Angeles MS4 Permit (NPDES No. CAS004001) Monitoring and Reporting Program.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 138271, Cyanide	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254255

Pollutant:

Cyanide

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The cyanide criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 5.2 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138305	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	1,1,2-Trichloroethane
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 138305, 1,1,2-Trichloroethane	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

256117

Pollutant:

1,1,2-Trichloroethane

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: Surface waters shall not contain concentrations of chemical constituents in amounts that adversely affect any designated beneficial use.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA National Recommended Water Quality Criteria (Gold Book) for freshwater aquatic life protection, chronic Lowest Observed Effect Level is 9,400 ug/L.

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138305, 1,1,2-Trichloroethane	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

256078

Pollutant:

1,1,2-Trichloroethane

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA National Recommended Water Quality Criteria (Gold Book) for freshwater aquatic life protection, chronic Lowest Observed Effect Level is 9,400 ug/L.

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138305, 1,1,2-Trichloroethane	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

256298

Pollutant:

1,1,2-Trichloroethane

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA National Recommended Water Quality Criteria (Gold Book) for freshwater aquatic life protection, chronic Lowest Observed Effect Level is 9,400 ug/L.

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138302	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Acrolein
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 138302, Acrolein	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253506

Pollutant:

Acrolein

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA recommended acrolein criterion for the protection of aquatic life in freshwater is 3 ug/L ( 4-day average).

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138302, Acrolein	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253487

Pollutant:

Acrolein

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA recommended acrolein criterion for the protection of aquatic life in freshwater is 3 ug/L ( 4-day average).

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138302, Acrolein	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253463

Pollutant:

Acrolein

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA recommended acrolein criterion for the protection of aquatic life in freshwater is 3 ug/L ( 4-day average).

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138303	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

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:	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 138303, Aldrin	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253356

Pollutant:

Aldrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The aldrin criterion maximum concentration (expressed as a 1-day average) to protect aquatic life in freshwater is 1.5 ug/L. The criterion of 3 ug/L provided in the California Toxics Rule is an instantaneous maximum concentration and was divided by 2 in order to better represent a criterion maximum concentration (CMC) value as specified in footnote (g) of Table (b)(1) of the California Toxics Rule (2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138303, Aldrin	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253360

Pollutant:

Aldrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138303, Aldrin	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253313

Pollutant:

Aldrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138304	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

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 138304, Alkalinity as CaCO3	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

256522

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

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: SMC00574 (SGMR00574).

Temporal Representation:

The samples were collected between the dates of 2017-05-03 and 2017-05-03

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138304, Alkalinity as CaCO3	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

256521

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

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: SMC16832 (SGMR16832).

Temporal Representation:

The samples were collected between the dates of 2018-07-10 and 2018-07-10

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138304, Alkalinity as CaCO3	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

251891

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Alkalinity as CaCO3.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

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: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2015-12-14 and 2016-02-04

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

Data for Various Pollutants in Various Water Bodies in Sanitation Districts of Los Angeles County, 2005-2010.


DECISION ID	150458	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Ammonia
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. Five 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 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. 0 of 251 samples exceeded the objective 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 150458, Ammonia	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

87817

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

217

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

0 out of 217 30-day averages exceeded the objective for ammonia. Only samples during the months when early life stages were present were assessed. A calendar month was considered as a 30-day averaging period.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Los Angeles Regional Water Quality Control Plan 30-day site specific objective for total ammonia as nitrogen is a function of pH, temperature, and the presence of early life stages. The site specific objective for San Gabriel River Reaches 2 and 3 (Confluence with San Jose Creek to Firestone Blvd.) has early life stages present from April 1st to September 30th.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected at monitoring stations San Jose Creek R2 (SG-R2), and San Jose Creek R12 (SG-R12).

Temporal Representation:

Samples were collected from June 2005 to October 2009. Samples at SG-R2 were collected weekly.

Environmental Conditions:

QAPP Information:

Samples were collected as part of an NPDES permit requirement. Receiving water data collected to represent the water body as a whole. No QAPP was submitted but an unsigned field manual was.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 150458, Ammonia	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253468

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support and the results are as follows: none of the sixteen 30-day averages exceeded the objective for ammonia. Only samples during the months when early life stages were present were assessed. A calendar month was considered as a 30-day averaging period.

Data Reference:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Total Ammonia criterion continuous concentration (expressed as a 30-day average) to protect aquatic life in freshwater is Temperature and pH dependent, and was calculated according to the formula listing in the Los Angeles Region Basin Plan for the 30-day Average Site-Specific Objective San Gabriel River, Reaches 2 and 3 for Ammonia-N. The objective used was for data collected from April 1 – September 30, when early life stages are presumed present.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (744616).

Temporal Representation:

Data for this waterbody was collected over the date range 2011-06-06 to 2019-10-10. Only data collected from April 1 – September 30, when early life stages are presumed present, were assessed in this line of evidence.

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 150458, Ammonia	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

316376

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support and the results are as follows: none of the sixteen 30-day averages exceeded the objective for ammonia. Only samples during the months when early life stages were absent were assessed. A calendar month was considered as a 30-day averaging period.

Data Reference:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Total Ammonia criterion continuous concentration (expressed as a 30-day average) to protect aquatic life in freshwater is Temperature and pH dependent, and was calculated according to the formula listing in the Los Angeles Region Basin Plan for the 30-day Average Site-Specific Objective San Gabriel River, Reaches 2 and 3 for Ammonia-N. The objective used was for data collected from October 1 – March 31, when early life stages are presumed absent

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (744616).

Temporal Representation:

Data for this waterbody was collected over the date range 2011-06-06 to 2019-10-10. Only data collected from October 1 – March 31, when early life stages are presumed absent, were assessed in this line of evidence.

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 150458, Ammonia	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

256771

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC16832 (SGMR16832).

Temporal Representation:

The samples were collected between the dates of 2018-07-10 and 2018-07-10

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 150458, Ammonia	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

257232

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Total Ammonia criterion continuous concentration (expressed as a 30-day average) to protect aquatic life in freshwater is Temperature and pH dependent, and was calculated according to the formula listing in the Los Angeles Region Basin Plan for the 30-day Average Site-Specific Objective San Gabriel River,
Reaches 2 and 3 for Ammonia-N. The objective used was for data collected from April 1 – September 30, when early life stages are presumed present.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC00574 (SGMR00574).

Temporal Representation:

The samples were collected between the dates of 2017-05-03 and 2017-05-03

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.


DECISION ID	138260	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Antimony
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. 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. 0 of 16, 0 of 14 and 0 of 2 samples exceeded the criteria 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 138260, Antimony	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253450

Pollutant:

Antimony

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA Quality Criteria for Water (Gold Book) states that for antimony toxicity to algae occurs at 610 ug/l. (USEPA, 1986)

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138260, Antimony	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253539

Pollutant:

Antimony

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA Quality Criteria for Water (Gold Book) states that for antimony toxicity to algae occurs at 610 ug/l. (USEPA, 1986)

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138260, Antimony	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

252002

Pollutant:

Antimony

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Antimony.

Data Reference:

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA Quality Criteria for Water (Gold Book) states that for antimony toxicity to algae occurs at 610 ug/l. (USEPA, 1986)

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2015-12-14 and 2016-02-04

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138260, Antimony	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253410

Pollutant:

Antimony

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA Quality Criteria for Water (Gold Book) states that for antimony toxicity to algae occurs at 610 ug/l. (USEPA, 1986)

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138260, Antimony	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253538

Pollutant:

Antimony

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA Quality Criteria for Water (Gold Book) states that for antimony toxicity to algae occurs at 610 ug/l. (USEPA, 1986)

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138260, Antimony	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253362

Pollutant:

Antimony

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA Quality Criteria for Water (Gold Book) states that for antimony toxicity to algae occurs at 610 ug/l. (USEPA, 1986)

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138260, Antimony	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

251980

Pollutant:

Antimony

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Antimony.

Data Reference:

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA Quality Criteria for Water (Gold Book) states that for antimony toxicity to algae occurs at 610 ug/l. (USEPA, 1986)

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2015-12-14 and 2016-02-04

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138260, Antimony	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253389

Pollutant:

Antimony

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA Quality Criteria for Water (Gold Book) states that for antimony toxicity to algae occurs at 610 ug/l. (USEPA, 1986)

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138261	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

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:	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. 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. 0 of 18 and 0 of 42 samples exceeded the CRITERIA 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 138261, Arsenic	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

251789

Pollutant:

Arsenic

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Arsenic.

Data Reference:

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The dissolved arsenic criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 150 ug/L. The conversion factor used to convert the total fraction criterion for arsenic to dissolved fraction criterion is 1. Therefore all data was considered to be representative of the dissolved fraction. (California Toxics Rule, 2000)

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2015-12-14 and 2016-02-04

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138261, Arsenic	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253502

Pollutant:

Arsenic

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138261, Arsenic	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

87906

Pollutant:

Arsenic

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

None of the 42 samples exceeded the criteria of 150 ug/L.

Data Reference:

Data for Various Pollutants in Various Water Bodies in Sanitation Districts of Los Angeles County, 2005-2010.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Surface waters shall not contain concentrations of chemical constituents in amounts that adversely affect any designated beneficial use.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

California Toxics Rule (CTR) lists criterion continuous concentrations (4-day average) to protect aquatic life in freshwater. The CTR for arsenic is 150 ug/L.

Guideline 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

Spatial Representation:

Samples were collected from San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam) from three sample stations: SG-R12 and SG-R2.

Temporal Representation:

Samples were collected monthly from June 2006 through May of 2010.

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 138261, Arsenic	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253479

Pollutant:

Arsenic

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138261, Arsenic	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253367

Pollutant:

Arsenic

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138261, Arsenic	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

257311

Pollutant:

Arsenic

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC00574 (SGMR00574).

Temporal Representation:

The samples were collected between the dates of 2017-05-03 and 2017-05-03

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138261, Arsenic	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

257521

Pollutant:

Arsenic

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC16832 (SGMR16832).

Temporal Representation:

The samples were collected between the dates of 2018-07-10 and 2018-07-10

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.


DECISION ID	138278	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Azinphos-methyl (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:	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 138278, Azinphos-methyl (Guthion)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253286

Pollutant:

Azinphos-methyl (Guthion)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Azinphos Methyl. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA National Recommended Water Quality Criteria for azinphos methyl for freshwater aquatic life protection is 0.01 ug/l (instantaneous maximum)

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

Data for this waterbody were collected over the date range 2012-08-06 to 2012-08-06

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138278, Azinphos-methyl (Guthion)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253284

Pollutant:

Azinphos-methyl (Guthion)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Azinphos Methyl. Although a total of 3 samples were collected, 3 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA National Recommended Water Quality Criteria for azinphos methyl for freshwater aquatic life protection is 0.01 ug/l (instantaneous maximum)

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

Data for this waterbody were collected over the date range 2011-08-10 to 2014-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138262	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Beryllium
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 138262, Beryllium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253881

Pollutant:

Beryllium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The Gold Book states that beryllium chronic toxicity to freshwater aquatic life occur at concentrations as low as 5.3 ug/L.

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138262, Beryllium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253657

Pollutant:

Beryllium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The Gold Book states that beryllium chronic toxicity to freshwater aquatic life occur at concentrations as low as 5.3 ug/L.

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138262, Beryllium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253817

Pollutant:

Beryllium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The Gold Book states that beryllium chronic toxicity to freshwater aquatic life occur at concentrations as low as 5.3 ug/L.

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138262, Beryllium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253839

Pollutant:

Beryllium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The Gold Book states that beryllium chronic toxicity to freshwater aquatic life occur at concentrations as low as 5.3 ug/L.

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138262, Beryllium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253620

Pollutant:

Beryllium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The Gold Book states that beryllium chronic toxicity to freshwater aquatic life occur at concentrations as low as 5.3 ug/L.

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138262, Beryllium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253947

Pollutant:

Beryllium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The Gold Book states that beryllium chronic toxicity to freshwater aquatic life occur at concentrations as low as 5.3 ug/L.

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138263	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

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:	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. 1 line of evidence is available in the administrative record to assess this pollutant. 0 of 59 samples exceeded the CRITERIA. 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. 0 of 59 samples exceeded the CRITERIA 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 138263, Cadmium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

251771

Pollutant:

Cadmium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Cadmium.

Data Reference:

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The dissolved cadmium criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is hardness dependent. The criterion when calculated using a default hardness of 100 mg/L is 2.2 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2015-12-14 and 2015-12-14

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138263, Cadmium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

257907

Pollutant:

Cadmium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC16832 (SGMR16832).

Temporal Representation:

The samples were collected between the dates of 2018-07-10 and 2018-07-10

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138263, Cadmium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253910

Pollutant:

Cadmium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138263, Cadmium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253908

Pollutant:

Cadmium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138263, Cadmium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253950

Pollutant:

Cadmium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138263, Cadmium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

87907

Pollutant:

Cadmium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

None of the 42 samples exceeded the hardness adjusted criteria.

Data Reference:

Data for Various Pollutants in Various Water Bodies in Sanitation Districts of Los Angeles County, 2005-2010.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Surface waters shall not contain concentrations of chemical constituents in amounts that adversely affect any designated beneficial use.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline 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

Spatial Representation:

Samples were collected from San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam) from three sample stations: SG-R12, SJC-R2 and SG-R2.

Temporal Representation:

Samples were collected monthly from June 2006 through May of 2010.

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 138263, Cadmium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

258057

Pollutant:

Cadmium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC00574 (SGMR00574).

Temporal Representation:

The samples were collected between the dates of 2017-05-03 and 2017-05-03

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.


DECISION ID	138264	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

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 138264, Chlordane	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255843

Pollutant:

Chlordane

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Total Chlordane. Although a total of 4 samples were collected, 4 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The chlordane criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.0043 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

Data for this waterbody were collected over the date range 2011-08-10 to 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138264, Chlordane	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255821

Pollutant:

Chlordane

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Total Chlordane. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The chlordane criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.0043 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

Data for this waterbody were collected over the date range 2019-08-07 to 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138264, Chlordane	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255865

Pollutant:

Chlordane

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Total Chlordane. Although a total of 4 samples were collected, 4 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The chlordane criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.0043 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

Data for this waterbody were collected over the date range 2012-08-06 to 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138265	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

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:	This pollutant is being considered for placement on the 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. 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. 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. 1 of 21, 2 of 20, 0 of 62 and 1 of 6 samples exceeded the reach specific water quality objective for chloride 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:	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 138265, Chloride	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

251970

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 0 of 4 samples exceeded the water quality threshold for Chloride.

Data Reference:

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The chloride criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 230000 ug/L (230 mg/L)(USEPA National Recommended Water Quality Criteria, 2006).

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2015-12-14 and 2017-06-07

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138265, Chloride	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

258257

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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 San Gabriel River Regional Monitoring Program data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Chloride.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC00574 (SGMR00574).

Temporal Representation:

The samples were collected between the dates of 2017-05-03 and 2017-05-03

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138265, Chloride	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253808

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-06-06 and 2019-10-10

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138265, Chloride	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

2463

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Agricultural Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

One out of 21 samples at this location exceeded the objective for chloride.

Summary of Results for the 2000-2001 Routine Monitoring at the San Gabriel River (Table B-5). ((LACDPW, 2004c).

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

150 mg/L (from the LARWQCB Basin Plan, Table 3-8, "Water Quality Objectives for Selected Constituents in Inland Surface Waters")

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The San Gabriel River Monitoring Station is located at an historic stream gage station (Stream Gage No. F263C-R), below San Gabriel River Parkway in Pico Rivera. At this location the upstream tributary area is 450 square miles. The San Gabriel River, at the gauging station, is a grouted rock-concrete stabilizer along the western levee and a natural section on the eastern side. Flow measurement and water sampling are conducted in the grouted rock area along the western levee of the river. The length of the concrete stabilizer is nearly 70 feet. The San Gabriel River sampling location has been an active stream gauging station since 1968.

Temporal Representation:

Samples taken between 10/28/2000 and 4/30/2003

Environmental Conditions:

Samples taken on 10/10/2002 and 4/30/2003 were 'DRY' samples. All others were 'WET'.

QAPP Information:

Detailed QA/QC contained in this report.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 138265, Chloride	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

25325

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Preservation of Rare & Endangered Species | Wildlife Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Two of 20 samples exceeded the Basin Plan reach specific water quality objectives for Chloride in San Gabriel River Reach 2. Water quality samples were taken and analyzed for Chloride in accordance with the Municipal Separate Storm Sewer System (MS4) permit monitoring and testing parameters.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan lists a specific water quality criterion of 250mg/L for Chloride in San Gabriel River Reach 2.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Temporal Representation:

Grab samples were taken approximately six per year (four wet-weather events and two dry-weather events), from October 2003 through April 2007.

Environmental Conditions:

QAPP Information:

Data was collected in compliance with the sampling and monitoring procedures detailed in County of Los Angeles MS4 Permit (NPDES No. CAS004001) Monitoring and Reporting Program.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 138265, Chloride	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

258398

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC16832 (SGMR16832).

Temporal Representation:

The samples were collected between the dates of 2018-07-10 and 2018-07-10

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138265, Chloride	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253762

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2016-09-14 and 2019-12-18

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138265, Chloride	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253786

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2020-01-13

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138266	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Chlorine
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 138266, Chlorine	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253872

Pollutant:

Chlorine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Chlorine, Total Residual. Although a total of 41 samples were collected, 41 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: Chlorine residual shall not be present in surface water any concentration that causes impairment of beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA recommended chlorine criterion for the protection of aquatic ife in freshwater is 11 ug/L (4-day average).

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

Data for this waterbody were collected over the date range 2011-06-06 to 2019-10-10

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138266, Chlorine	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253934

Pollutant:

Chlorine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Chlorine, Total Residual. Although a total of 27 samples were collected, 27 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: Chlorine residual shall not be present in surface water any concentration that causes impairment of beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA recommended chlorine criterion for the protection of aquatic ife in freshwater is 11 ug/L (4-day average).

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

Data for this waterbody were collected over the date range 2012-08-06 to 2020-01-13

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138266, Chlorine	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253811

Pollutant:

Chlorine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Chlorine, Total Residual. Although a total of 15 samples were collected, 15 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: Chlorine residual shall not be present in surface water any concentration that causes impairment of beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA recommended chlorine criterion for the protection of aquatic ife in freshwater is 11 ug/L (4-day average).

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

Data for this waterbody were collected over the date range 2016-09-14 to 2019-12-16

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138267	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

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 138267, Chlorpyrifos	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253791

Pollutant:

Chlorpyrifos

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Chlorpyrifos. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The freshwater criterion continuous concentration to protect aquatic organisms is 0.015 ug/L (Siepmann and Finlayson 2000, with minor corrections to significant figures as described in Beaulaurier et al., 2005).

Guideline Reference:

Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game

Guideline Reference:

Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game (with minor corrections to significant figures as described in Beaulaurier et al., 2005).

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

Data for this waterbody were collected over the date range 2015-08-03 to 2015-08-03

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138267, Chlorpyrifos	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253814

Pollutant:

Chlorpyrifos

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Chlorpyrifos. Although a total of 4 samples were collected, 4 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

Data for this waterbody were collected over the date range 2016-08-03 to 2019-08-14

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138267, Chlorpyrifos	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253837

Pollutant:

Chlorpyrifos

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Chlorpyrifos. Although a total of 2 samples were collected, 2 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

Data for this waterbody were collected over the date range 2019-08-07 to 2019-12-01

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138306	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

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. 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. 0 of 42 and 0 of 18 samples exceeded the CRITERIA 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 138306, Chromium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253898

Pollutant:

Chromium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The dissolved chromium (III) criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is is hardness dependent as described in Table 1 of paragraph (b)(1). The value calculated when using a default hardness of 100 mg/L is 180 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138306, Chromium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253632

Pollutant:

Chromium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138306, Chromium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

258653

Pollutant:

Chromium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC16832 (SGMR16832).

Temporal Representation:

The samples were collected between the dates of 2018-07-10 and 2018-07-10

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138306, Chromium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

251842

Pollutant:

Chromium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Chromium.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2015-12-14 and 2016-02-04

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

Data for Various Pollutants in Various Water Bodies in Sanitation Districts of Los Angeles County, 2005-2010.

Line of Evidence (LOE) for Decision ID 138306, Chromium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

87914

Pollutant:

Chromium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

None of the 42 samples exceeded the hardness adjusted criteria.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Surface waters shall not contain concentrations of chemical constituents in amounts that adversely affect any designated beneficial use.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline 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

Spatial Representation:

Samples were collected from San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam) from three sample stations: SG-R12, SJC-R2 and SG-R2.

Temporal Representation:

Samples were collected monthly from June 2006 through May of 2010.

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 138306, Chromium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

258695

Pollutant:

Chromium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC00574 (SGMR00574).

Temporal Representation:

The samples were collected between the dates of 2017-05-03 and 2017-05-03

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138306, Chromium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254076

Pollutant:

Chromium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138268	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Chromium, hexavalent
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. 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. 0 of 10, 0 of 5 and 0 of 38 samples exceeded the criteria 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 138268, Chromium, hexavalent	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254305

Pollutant:

Chromium, hexavalent

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The dissolved chromium (VI) criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 11 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2012-08-06

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138268, Chromium, hexavalent	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254105

Pollutant:

Chromium, hexavalent

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The dissolved chromium (VI) criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 11 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138268, Chromium, hexavalent	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254104

Pollutant:

Chromium, hexavalent

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The dissolved chromium (VI) criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 11 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2016-08-03 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138268, Chromium, hexavalent	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

87915

Pollutant:

Chromium, hexavalent

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

None of the 38 samples exceeded the criteria of 11 ug/L.

Data Reference:

Data for Various Pollutants in Various Water Bodies in Sanitation Districts of Los Angeles County, 2005-2010.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Surface waters shall not contain concentrations of chemical constituents in amounts that adversely affect any designated beneficial use.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

California Toxics Rule (CTR) lists criterion continuous concentrations (4-day average) to protect aquatic life in freshwater. The CTR for hexavalent chromium is 11 ug/L.

Guideline 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

Spatial Representation:

Samples were collected from San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam) from three sample stations: SG-R12, SJC-R2 and SG-R2.

Temporal Representation:

Samples were collected monthly from June 2006 through May of 2010.

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 138268, Chromium, hexavalent	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254015

Pollutant:

Chromium, hexavalent

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The dissolved chromium (VI) criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 11 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2013-05-15 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138268, Chromium, hexavalent	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254307

Pollutant:

Chromium, hexavalent

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The dissolved chromium (VI) criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 11 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-05-04

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138268, Chromium, hexavalent	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

251928

Pollutant:

Chromium, hexavalent

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chromium VI.

Data Reference:

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The dissolved chromium (VI) criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 11 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2015-12-14 and 2015-12-14

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.


DECISION ID	138269	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Chromium, trivalent
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 138269, Chromium, trivalent	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254176

Pollutant:

Chromium, trivalent

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The dissolved chromium (III) criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is hardness dependent. The criterion when calculated using a default hardness of 100 mg/L is 180 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138269, Chromium, trivalent	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254219

Pollutant:

Chromium, trivalent

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138269, Chromium, trivalent	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254150

Pollutant:

Chromium, trivalent

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	149824	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	DDT (Dichlorodiphenyltrichloroethane)
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 149824, DDT (Dichlorodiphenyltrichloroethane)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254168

Pollutant:

DDT (Dichlorodiphenyltrichloroethane)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for DDT(p,p'). Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The DDT(4,4') criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.001 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

Data for this waterbody were collected over the date range 2019-08-07 to 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 149824, DDT (Dichlorodiphenyltrichloroethane)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254166

Pollutant:

DDT (Dichlorodiphenyltrichloroethane)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for DDT(p,p'). Although a total of 4 samples were collected, 4 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The DDT(4,4') criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.001 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

Data for this waterbody were collected over the date range 2012-08-06 to 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 149824, DDT (Dichlorodiphenyltrichloroethane)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254050

Pollutant:

DDT (Dichlorodiphenyltrichloroethane)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for DDT(p,p'). Although a total of 4 samples were collected, 4 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The DDT(4,4') criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.001 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

Data for this waterbody were collected over the date range 2011-08-10 to 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138307	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

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:	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 138307, Demeton	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253956

Pollutant:

Demeton

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA National Recommended Water Quality criterion for demeton for freshwater aquatic life protection is 0.1 ug/l (4 day average)

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2014-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138307, Demeton	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253983

Pollutant:

Demeton

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA National Recommended Water Quality criterion for demeton for freshwater aquatic life protection is 0.1 ug/l (4 day average)

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2012-08-06

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138273	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

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 138273, Diazinon	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254454

Pollutant:

Diazinon

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The freshwater chronic value for diazinon is 0.10 ug/L (4 day average)(Finlayson, 2004).

Guideline Reference:

Water quality for diazinon. Memorandum to J. Karkoski, Central Valley RWQCB. Rancho Cordova, CA: Pesticide Investigation Unit, CA Department of Fish and Game

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-03

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138273, Diazinon	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254455

Pollutant:

Diazinon

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The freshwater chronic value for diazinon is 0.10 ug/L (4 day average)(Finlayson, 2004).

Guideline Reference:

Water quality for diazinon. Memorandum to J. Karkoski, Central Valley RWQCB. Rancho Cordova, CA: Pesticide Investigation Unit, CA Department of Fish and Game

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-12-01

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138273, Diazinon	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254542

Pollutant:

Diazinon

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The freshwater chronic value for diazinon is 0.10 ug/L (4 day average)(Finlayson, 2004).

Guideline Reference:

Water quality for diazinon. Memorandum to J. Karkoski, Central Valley RWQCB. Rancho Cordova, CA: Pesticide Investigation Unit, CA Department of Fish and Game

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-08-14

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138274	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Dieldrin
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 138274, Dieldrin	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254504

Pollutant:

Dieldrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The dieldrin criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.056 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138274, Dieldrin	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254642

Pollutant:

Dieldrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The dieldrin criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.056 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138274, Dieldrin	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254572

Pollutant:

Dieldrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The dieldrin criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.056 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138275	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Endosulfan sulfate
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 138275, Endosulfan sulfate	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254653

Pollutant:

Endosulfan sulfate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA National Recommended Water Quality Criteria toxicity threshold for endosulfan sulfate for freshwater aquatic life protection is 0.056 ug/l (24 hour average)

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138275, Endosulfan sulfate	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254580

Pollutant:

Endosulfan sulfate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA National Recommended Water Quality Criteria toxicity threshold for endosulfan sulfate for freshwater aquatic life protection is 0.056 ug/l (24 hour average)

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138275, Endosulfan sulfate	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254607

Pollutant:

Endosulfan sulfate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA National Recommended Water Quality Criteria toxicity threshold for endosulfan sulfate for freshwater aquatic life protection is 0.056 ug/l (24 hour average)

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138276	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

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 138276, Endrin	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254829

Pollutant:

Endrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The endrin criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.036 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138276, Endrin	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254807

Pollutant:

Endrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The endrin criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.036 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138276, Endrin	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254848

Pollutant:

Endrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The endrin criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.036 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138277	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Glyphosate
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 138277, Glyphosate	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

252112

Pollutant:

Glyphosate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Glyphosate.

Data Reference:

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The evaluation guideline for glyphosate is the USEPA Aquatic Life Benchmark of 11,900 ug/L for a vascular plant (acute).

Guideline Reference:

OPP Aquatic Life Benchmarks

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2015-12-14 and 2015-12-14

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.


DECISION ID	138279	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Heptachlor
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 138279, Heptachlor	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254964

Pollutant:

Heptachlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Heptachlor. Although a total of 4 samples were collected, 4 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The heptachlor criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.0038 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

Data for this waterbody were collected over the date range 2012-08-06 to 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138279, Heptachlor	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254987

Pollutant:

Heptachlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Heptachlor. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The heptachlor criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.0038 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

Data for this waterbody were collected over the date range 2019-08-07 to 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138279, Heptachlor	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255009

Pollutant:

Heptachlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Heptachlor. Although a total of 4 samples were collected, 4 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The heptachlor criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.0038 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

Data for this waterbody were collected over the date range 2011-08-10 to 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138280	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

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 138280, Heptachlor epoxide	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254946

Pollutant:

Heptachlor epoxide

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Heptachlor Epoxide. Although a total of 4 samples were collected, 4 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The heptachlor epoxide criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.0038 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

Data for this waterbody were collected over the date range 2011-08-10 to 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138280, Heptachlor epoxide	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254801

Pollutant:

Heptachlor epoxide

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Heptachlor Epoxide. Although a total of 4 samples were collected, 4 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The heptachlor epoxide criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.0038 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

Data for this waterbody were collected over the date range 2012-08-06 to 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138280, Heptachlor epoxide	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254904

Pollutant:

Heptachlor epoxide

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Heptachlor Epoxide. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The heptachlor epoxide criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.0038 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

Data for this waterbody were collected over the date range 2019-08-07 to 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138281	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Iron
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. 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. 0 of 0, 0 of 3, 0 of 4 and 2 of 29 samples exceeded the CRITERIA 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 138281, Iron	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

2462

Pollutant:

Iron

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:

It is unknown whether any of the 18 samples taken at this location exceeded a WQO, criteria or guideline for total Iron. (LACDPW, 2004c).

Summary of Results for the 2000-2001 Routine Monitoring at the San Gabriel River (Table B-5)

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

There is no fresh water WQO criteria or guideline for total lead linked or applicable with protection of REC1, Aquatic Life or MUN BUs.

Objective/Criterion Reference:

Data for Various Pollutants in Various Water Bodies in Sanitation Districts of Los Angeles County, 2005-2010.

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Temporal Representation:

Samples taken between 10/28/2000 and 4/30/2003

Environmental Conditions:

Samples taken on 10/10/2002 and 4/30/2003 were 'DRY' samples. All others were 'WET'.

QAPP Information:

Detailed QA/QC contained in this report.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 138281, Iron	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

87918

Pollutant:

Iron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Two of the 29 samples exceeded the criteria of 1,000 ug/L.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Surface waters shall not contain concentrations of chemical constituents in amounts that adversely affect any designated beneficial use.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

National Recommended Water Quality Criteria Continuous Concentrations are intended protect aquatic organisms from chronic exposures (expressed as 4-day average concentration) in freshwater. The evaluation guideline for iron is 1,000 ug/L to protect warm freshwater habitat.

Guideline Reference:

Spatial Representation:

Samples were collected from San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam) from three sample stations: SG-R12, SJC-R2 and SG-R2.

Temporal Representation:

Samples were collected monthly from June 2006 through May of 2010.

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 138281, Iron	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

262317

Pollutant:

Iron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

National Recommended Water Quality Criteria Continuous Concentrations are intended protect freshwater aquatic organisms from chronic exposures and are expressed as 4-day average concentrations. The evaluation guideline for Iron is 1,000 ug/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC16832 (SGMR16832).

Temporal Representation:

The samples were collected between the dates of 2018-07-10 and 2018-07-10

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138281, Iron	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

252025

Pollutant:

Iron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Iron.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2015-12-14 and 2015-12-14

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138281, Iron	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

262524

Pollutant:

Iron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC00574 (SGMR00574).

Temporal Representation:

The samples were collected between the dates of 2017-05-03 and 2017-05-03

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138281, Iron	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

252500

Pollutant:

Iron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Iron.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2015-12-14 and 2016-02-04

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138281, Iron	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

262358

Pollutant:

Iron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC16832 (SGMR16832).

Temporal Representation:

The samples were collected between the dates of 2018-07-10 and 2018-07-10

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138281, Iron	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

262501

Pollutant:

Iron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC00574 (SGMR00574).

Temporal Representation:

The samples were collected between the dates of 2017-05-03 and 2017-05-03

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.


DECISION ID	138283	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

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 138283, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254854

Pollutant:

Lindane/gamma Hexachlorocyclohexane (gamma-HCH)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The gamma-BHC (Lindane, gamma-HCH) criterion maximum concentration to protect aquatic life in freshwater is 0.95 ug/L. (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138283, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254813

Pollutant:

Lindane/gamma Hexachlorocyclohexane (gamma-HCH)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The gamma-BHC (Lindane, gamma-HCH) criterion maximum concentration to protect aquatic life in freshwater is 0.95 ug/L. (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138283, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

252166

Pollutant:

Lindane/gamma Hexachlorocyclohexane (gamma-HCH)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 0 of 4 samples exceeded the water quality threshold for HCH, gamma-.

Data Reference:

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The gamma-BHC (Lindane, gamma-HCH) criterion maximum concentration to protect aquatic life in freshwater is 0.95 ug/L. (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2016-11-21 and 2019-12-05

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138283, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254795

Pollutant:

Lindane/gamma Hexachlorocyclohexane (gamma-HCH)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The gamma-BHC (Lindane, gamma-HCH) criterion maximum concentration to protect aquatic life in freshwater is 0.95 ug/L. (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138284	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Malathion
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 138284, Malathion	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255203

Pollutant:

Malathion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Malathion. Although a total of 3 samples were collected, 3 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Aquatic life should not be affected unacceptably if the 4-day average concentration of malathion does not exceed 0.028 ug/L (UC Davis Aquatic Life Criteria).

Guideline Reference:

Aquatic life water quality criteria derived via the UC Davis method: l. Organophosphate insecticides. Reviews of Environmental Contamination and Toxicology 216:1-48.

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

Data for this waterbody were collected over the date range 2011-08-10 to 2014-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138284, Malathion	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255244

Pollutant:

Malathion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Malathion. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Aquatic life should not be affected unacceptably if the 4-day average concentration of malathion does not exceed 0.028 ug/L (UC Davis Aquatic Life Criteria).

Guideline Reference:

Aquatic life water quality criteria derived via the UC Davis method: l. Organophosphate insecticides. Reviews of Environmental Contamination and Toxicology 216:1-48.

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

Data for this waterbody were collected over the date range 2012-08-06 to 2012-08-06

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	149825	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

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:	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. 4 lines of evidence are available in the administrative record to assess this pollutant. 0 of 17 samples exceeded the CRITERIA. 0 of 14 samples exceeded the CRITERIA. 0 of 3 samples exceeded the CRITERIA. 0 of 63 samples exceeded the CRITERIA. 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. 0 of 17, 0 of 14, 0 of 3 and 0 of 63 samples exceeded the CRITERIA 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 149825, Mercury	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

263298

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

National Recommended Water Quality Criteria Continuous Concentration (4-day average concentrations) for freshwater aquatic organisms exposure to total mercury is 0.77 ug/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC00574 (SGMR00574).

Temporal Representation:

The samples were collected between the dates of 2017-05-03 and 2017-05-03

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 149825, Mercury	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255267

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

National Recommended Water Quality Criteria Continuous Concentration (4-day average concentrations) for freshwater aquatic organisms exposure to total mercury is 0.77 ug/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 149825, Mercury	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

263276

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

National Recommended Water Quality Criteria Continuous Concentration (4-day average concentrations) for freshwater aquatic organisms exposure to total mercury is 0.77 ug/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC00574 (SGMR00574).

Temporal Representation:

The samples were collected between the dates of 2017-05-03 and 2017-05-03

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

Data for Various Pollutants in Various Water Bodies in Sanitation Districts of Los Angeles County, 2005-2010.

Line of Evidence (LOE) for Decision ID 149825, Mercury	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

87815

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

None of the 63 samples exceeded the criteria of 0.77 ug/L.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Surface waters shall not contain concentrations of chemical constituents in amounts that adversely affect any designated beneficial use.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

National Recommended Water Quality Criteria Continuous Concentrations (4-day average concentrations) for freshwater aquatic organisms exposure to elemental mercury is 0.77 ug/L.

Guideline Reference:

Spatial Representation:

Samples were collected from San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam) from two sample stations: SJC-R12 also called SG-R12 and SJC-R2 also called SG-R2.

Temporal Representation:

Samples were collected monthly from June 2006 through May of 2010.

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 149825, Mercury	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255268

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

National Recommended Water Quality Criteria Continuous Concentration (4-day average concentrations) for freshwater aquatic organisms exposure to total mercury is 0.77 ug/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 149825, Mercury	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

252509

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Mercury.

Data Reference:

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

National Recommended Water Quality Criteria Continuous Concentration (4-day average concentrations) for freshwater aquatic organisms exposure to total mercury is 0.77 ug/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2015-12-14 and 2016-02-04

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 149825, Mercury	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255208

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

National Recommended Water Quality Criteria Continuous Concentration (4-day average concentrations) for freshwater aquatic organisms exposure to total mercury is 0.77 ug/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 149825, Mercury	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

252636

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Mercury.

Data Reference:

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

National Recommended Water Quality Criteria Continuous Concentration (4-day average concentrations) for freshwater aquatic organisms exposure to total mercury is 0.77 ug/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2015-12-14 and 2015-12-14

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 149825, Mercury	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255290

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

National Recommended Water Quality Criteria Continuous Concentration (4-day average concentrations) for freshwater aquatic organisms exposure to total mercury is 0.77 ug/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 149825, Mercury	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

263441

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

National Recommended Water Quality Criteria Continuous Concentration (4-day average concentrations) for freshwater aquatic organisms exposure to total mercury is 0.77 ug/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC16832 (SGMR16832).

Temporal Representation:

The samples were collected between the dates of 2018-07-10 and 2018-07-10

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 149825, Mercury	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255205

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

National Recommended Water Quality Criteria Continuous Concentration (4-day average concentrations) for freshwater aquatic organisms exposure to total mercury is 0.77 ug/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 149825, Mercury	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

263436

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

National Recommended Water Quality Criteria Continuous Concentration (4-day average concentrations) for freshwater aquatic organisms exposure to total mercury is 0.77 ug/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC16832 (SGMR16832).

Temporal Representation:

The samples were collected between the dates of 2018-07-10 and 2018-07-10

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.


DECISION ID	138285	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Methoxychlor
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 138285, Methoxychlor	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255039

Pollutant:

Methoxychlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA national ambient water quality criterion for freshwater aquatic life Criterion Continuous Concentration (CCC) expressed as a 4-day average for methoxychlor is 0.03 ug/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138285, Methoxychlor	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255381

Pollutant:

Methoxychlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA national ambient water quality criterion for freshwater aquatic life Criterion Continuous Concentration (CCC) expressed as a 4-day average for methoxychlor is 0.03 ug/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138285, Methoxychlor	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255356

Pollutant:

Methoxychlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA national ambient water quality criterion for freshwater aquatic life Criterion Continuous Concentration (CCC) expressed as a 4-day average for methoxychlor is 0.03 ug/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138286	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Mirex
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 138286, Mirex	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255235

Pollutant:

Mirex

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Mirex. Although a total of 3 samples were collected, 3 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA national recommended criterion continuous concentration for mirex for the protection of freshwater aquatic life is 0.001 µg/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

Data for this waterbody were collected over the date range 2011-08-10 to 2014-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138286, Mirex	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255273

Pollutant:

Mirex

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Mirex. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA national recommended criterion continuous concentration for mirex for the protection of freshwater aquatic life is 0.001 µg/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

Data for this waterbody were collected over the date range 2012-08-06 to 2012-08-06

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138287	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Naphthalene
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 138287, Naphthalene	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255046

Pollutant:

Naphthalene

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: 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 Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA recommended naphthalene criterion for the protection of freshwater aquatic life is 620 ug/l. (EPA 440/5-80-059)

Guideline Reference:

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 138287, Naphthalene	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

252540

Pollutant:

Naphthalene

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Naphthalene.

Data Reference:

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA recommended naphthalene criterion for the protection of freshwater aquatic life is 620 ug/l. (EPA 440/5-80-059)

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2016-12-17 and 2019-12-05

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138287, Naphthalene	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255338

Pollutant:

Naphthalene

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA recommended naphthalene criterion for the protection of freshwater aquatic life is 620 ug/l. (EPA 440/5-80-059)

Guideline Reference:

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 138287, Naphthalene	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255042

Pollutant:

Naphthalene

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA recommended naphthalene criterion for the protection of freshwater aquatic life is 620 ug/l. (EPA 440/5-80-059)

Guideline Reference:

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):


DECISION ID	138288	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

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 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. 1 line of evidence is available in the administrative record to assess this pollutant. 0 of 60 samples exceeded the CRITERIA. 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. 0 of 60 samples exceeded the CRITERIA 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 138288, Nickel	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

263789

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The dissolved nickel criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is hardness dependent. The criterion when calculated using a default hardness of 100 mg/L is 52 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC16832 (SGMR16832).

Temporal Representation:

The samples were collected between the dates of 2018-07-10 and 2018-07-10

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138288, Nickel	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255152

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138288, Nickel	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255110

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138288, Nickel	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255176

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138288, Nickel	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

263835

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC00574 (SGMR00574).

Temporal Representation:

The samples were collected between the dates of 2017-05-03 and 2017-05-03

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138288, Nickel	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

252667

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Nickel.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2015-12-14 and 2016-02-04

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

Data for Various Pollutants in Various Water Bodies in Sanitation Districts of Los Angeles County, 2005-2010.

Line of Evidence (LOE) for Decision ID 138288, Nickel	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

87816

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

None of the 42 samples exceeded the hardness adjusted criteria.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Surface waters shall not contain concentrations of chemical constituents in amounts that adversely affect any designated beneficial use.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline 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

Spatial Representation:

Samples were collected from San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam) from three sample stations: SG-R12, SJC-R2 and SG-R2.

Temporal Representation:

Samples were collected monthly from June 2006 through May of 2010.

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	149332	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

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:	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 is 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 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. 0 of 28 samples exceeded the objective 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 149332, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

302580

Pollutant:

Nitrate/Nitrite (Nitrite + Nitrate as N)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region (page 3-34) states that: Waters shall not exceed 10 mg/L nitrogen as nitrate-nitrogen plus nitrite-nitrogen (NO3-N + NO2-N).

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2015-08-05 and 2019-10-10

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 149332, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

302583

Pollutant:

Nitrate/Nitrite (Nitrite + Nitrate as N)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region (page 3-34) states that: Waters shall not exceed 10 mg/L nitrogen as nitrate-nitrogen plus nitrite-nitrogen (NO3-N + NO2-N).

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2016-09-14 and 2019-12-18

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 149332, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

302582

Pollutant:

Nitrate/Nitrite (Nitrite + Nitrate as N)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region (page 3-34) states that: Waters shall not exceed 10 mg/L nitrogen as nitrate-nitrogen plus nitrite-nitrogen (NO3-N + NO2-N).

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2015-06-22 and 2020-01-13

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	149826	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Nitrogen, Nitrate
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. 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. 0 of 43 and 0 of 6 samples exceeded the OBJECTIVE 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 149826, Nitrogen, Nitrate	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

302557

Pollutant:

Nitrogen, Nitrate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region (page 3-34) states that: Waters shall not exceed 10 mg/L as nitrate-nitrogen (NO3-N).

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2018-05-02

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 149826, Nitrogen, Nitrate	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

302576

Pollutant:

Nitrogen, Nitrate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region (page 3-34) states that: Waters shall not exceed 10 mg/L as nitrate-nitrogen (NO3-N).

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-06-06 and 2017-01-26

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 149826, Nitrogen, Nitrate	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

302206

Pollutant:

Nitrogen, Nitrate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region (page 3-34) states that: Waters shall not exceed 10 mg/L as nitrate-nitrogen (NO3-N).

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC00574 (SGMR00574).

Temporal Representation:

The samples were collected between the dates of 2017-05-03 and 2017-05-03

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 149826, Nitrogen, Nitrate	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

302491

Pollutant:

Nitrogen, Nitrate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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 LA County MS4 data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support and results are as follows: 0 of 4 samples exceeded the water quality threshold for Nitrate as N.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region (page 3-34) states that: Waters shall not exceed 10 mg/L as nitrate-nitrogen (NO3-N).

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2015-12-14 and 2017-06-07

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 149826, Nitrogen, Nitrate	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

302574

Pollutant:

Nitrogen, Nitrate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region (page 3-34) states that: Waters shall not exceed 10 mg/L as nitrate-nitrogen (NO3-N).

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2016-09-14 and 2016-09-14

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 149826, Nitrogen, Nitrate	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

302283

Pollutant:

Nitrogen, Nitrate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region (page 3-34) states that: Waters shall not exceed 10 mg/L as nitrate-nitrogen (NO3-N).

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC16832 (SGMR16832).

Temporal Representation:

The samples were collected between the dates of 2018-07-10 and 2018-07-10

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.


DECISION ID	138289	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Organophosphate Pesticides
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 138289, Organophosphate Pesticides	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255717

Pollutant:

Organophosphate Pesticides

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The evaluation guideline for the protection of aquatic life from the additive effects of the organophosphate pesticides chlorpyrifos and diazinon is one toxic unit equivalent. A toxic unit equivalent is equal to the sum of chlorpyrifos and diazinon from a single sample, each having their reported concentration divided their respective evaluation guideline prior to being summed. If this results in a value greater than one, the sample is considered to be in exceedance of the water quality standard. (Bailey et al., 1997).

Guideline Reference:

Joint acute toxicity of Diazinon and Chlorpyrifos to Ceriodaphnia dubia.

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-03

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138289, Organophosphate Pesticides	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255594

Pollutant:

Organophosphate Pesticides

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Joint acute toxicity of Diazinon and Chlorpyrifos to Ceriodaphnia dubia.

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-08-14

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138289, Organophosphate Pesticides	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255654

Pollutant:

Organophosphate Pesticides

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Joint acute toxicity of Diazinon and Chlorpyrifos to Ceriodaphnia dubia.

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-12-01

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	151914	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Oxygen, Dissolved
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. Six lines of evidence are available in the administrative record to assess this pollutant. 0 of 126 samples exceeded 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. 0 of 126 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:	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 151914, Oxygen, Dissolved	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

308076

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region (page 3-39) states that: The dissolved oxygen content of all surface waters designated as WARM shall not be depressed below 5 mg/L as a result of waste discharges.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2016-09-14 and 2019-12-16

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 151914, Oxygen, Dissolved	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

87818

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Numeric data generated from 65 averages of Dissolved Oxygen concentrations had no exceedances.

Data Reference:

Data for Various Pollutants in Various Water Bodies in Sanitation Districts of Los Angeles County, 2005-2010.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Dissolved Oxygen Water Quality Objective of all surface waters designated as Warm Fresh Water Aquatic Habitat shall not be depressed below 5 mg/l.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected from the SJC-R2 and SJC-R12 stations.

Temporal Representation:

Samples were collected approximately once a month from July 2005 to November 2009.

Environmental Conditions:

QAPP Information:

NPDES quality assurance.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 151914, Oxygen, Dissolved	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

307905

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2013-04-03 and 2020-01-13

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 151914, Oxygen, Dissolved	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

308511

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC00574 (SGMR00574).

Temporal Representation:

The samples were collected between the dates of 2017-05-03 and 2017-05-03

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 151914, Oxygen, Dissolved	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

307879

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-06-06 and 2019-10-10

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 151914, Oxygen, Dissolved	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

308244

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC16832 (SGMR16832).

Temporal Representation:

The samples were collected between the dates of 2018-07-10 and 2018-07-10

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.


DECISION ID	138294	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	PCBs (Polychlorinated biphenyls)
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 138294, PCBs (Polychlorinated biphenyls)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255397

Pollutant:

PCBs (Polychlorinated biphenyls)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for PCBs (Polychlorinated biphenyls). Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The PCB, total aroclors criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.014 ug/L. This value corresponds to the sum of aroclors 1242, 1254, 1221, 1232, 1248, 1260, and 1016 (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

Data for this waterbody were collected over the date range 2019-08-07 to 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138294, PCBs (Polychlorinated biphenyls)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255619

Pollutant:

PCBs (Polychlorinated biphenyls)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for PCBs (Polychlorinated biphenyls). Although a total of 4 samples were collected, 4 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

Data for this waterbody were collected over the date range 2012-08-06 to 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138294, PCBs (Polychlorinated biphenyls)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255682

Pollutant:

PCBs (Polychlorinated biphenyls)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for PCBs (Polychlorinated biphenyls). Although a total of 4 samples were collected, 4 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

Data for this waterbody were collected over the date range 2011-08-10 to 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138291	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	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 138291, Parathion	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255468

Pollutant:

Parathion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Parathion, Ethyl. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA recommended freshwater aquatic life ambient water quality chronic criteria for parathion is 0.013 ug/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

Data for this waterbody were collected over the date range 2012-08-06 to 2012-08-06

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138291, Parathion	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255445

Pollutant:

Parathion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Parathion, Ethyl. Although a total of 3 samples were collected, 3 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA recommended freshwater aquatic life ambient water quality chronic criteria for parathion is 0.013 ug/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

Data for this waterbody were collected over the date range 2011-08-10 to 2014-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138292	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Pentachlorophenol (PCP)
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 138292, Pentachlorophenol (PCP)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255562

Pollutant:

Pentachlorophenol (PCP)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The pentachlorophenol criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is pH dependent. The criterion using a default pH value of 7.8 (when pH data is not present) is 15 ug/L. (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138292, Pentachlorophenol (PCP)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255537

Pollutant:

Pentachlorophenol (PCP)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138292, Pentachlorophenol (PCP)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

252718

Pollutant:

Pentachlorophenol (PCP)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Pentachlorophenol.

Data Reference:

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2016-02-19 and 2016-12-17

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138292, Pentachlorophenol (PCP)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255494

Pollutant:

Pentachlorophenol (PCP)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138259	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Profenofos
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 138259, Profenofos	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

252759

Pollutant:

Profenofos

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Profenofos.

Data Reference:

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The evaluation guideline for profenofos is the USEPA Aquatic Life Benchmark of 0.2 ug/L for an invertebrate (chronic).

Guideline Reference:

OPP Aquatic Life Benchmarks

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2015-12-14 and 2015-12-14

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.


DECISION ID	138295	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Selenium
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. 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. 0 of 66, 0 of 62, 0 of 4 and 0 of 72 samples exceeded the CRITERIA 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 138295, Selenium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255851

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The selenium criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 5 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-06-06 and 2019-10-10

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138295, Selenium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255961

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The selenium criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 5 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2020-01-13

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138295, Selenium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

265862

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The selenium criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 5 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC16832 (SGMR16832).

Temporal Representation:

The samples were collected between the dates of 2018-07-10 and 2018-07-10

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138295, Selenium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

265937

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The selenium criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 5 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC00574 (SGMR00574).

Temporal Representation:

The samples were collected between the dates of 2017-05-03 and 2017-05-03

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138295, Selenium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

253003

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Selenium.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The selenium criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 5 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2015-12-14 and 2016-02-04

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138295, Selenium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255960

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The selenium criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 5 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2020-01-13

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138295, Selenium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255913

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The selenium criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 5 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2016-09-14 and 2019-12-16

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138295, Selenium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255937

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The selenium criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 5 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-06-06 and 2019-10-10

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138295, Selenium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

265958

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The selenium criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 5 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC00574 (SGMR00574).

Temporal Representation:

The samples were collected between the dates of 2017-05-03 and 2017-05-03

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138295, Selenium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

265841

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The selenium criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 5 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC16832 (SGMR16832).

Temporal Representation:

The samples were collected between the dates of 2018-07-10 and 2018-07-10

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138295, Selenium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

252983

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Selenium.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The selenium criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 5 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2015-12-14 and 2016-02-04

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138295, Selenium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255849

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The selenium criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 5 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2016-09-14 and 2019-12-16

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138295, Selenium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

87825

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

None of the 72 samples exceeded the criteria of 5 ug/L.

Data Reference:

Data for Various Pollutants in Various Water Bodies in Sanitation Districts of Los Angeles County, 2005-2010.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Surface waters shall not contain concentrations of chemical constituents in amounts that adversely affect any designated beneficial use.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

California Toxics Rule (CTR) lists criterion continuous concentrations (4-day average) to protect aquatic life in freshwater. The CTR for selenium is 5.0 ug/L.

Guideline 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

Spatial Representation:

Samples were collected from San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam) from two sample stations: SJC-R12 also called SG-R12 and SJC-R2 also called SG-R2.

Temporal Representation:

Samples were collected monthly from June 2006 through May of 2010.

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	138296	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Silver
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. 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. 0 of 14 and 0 of 41 samples exceeded the CRITERIA 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 138296, Silver	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255832

Pollutant:

Silver

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The dissolved silver criterion maximum concentration (CMC) to protect aquatic life in freshwater is hardnesss dependent. The criterion when calculated using a default hardness of 100 mg/L is 3.4 ug/L. This criterion was divided by 2 in order to better represent a CMC value as specified in footnote (g) of Table (b)(1) of the California Toxics Rule, 2000.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138296, Silver	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255784

Pollutant:

Silver

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138296, Silver	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255831

Pollutant:

Silver

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138296, Silver	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

87826

Pollutant:

Silver

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

None of the 41 samples exceeded the hardness adjusted criteria.

Data Reference:

Data for Various Pollutants in Various Water Bodies in Sanitation Districts of Los Angeles County, 2005-2010.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Surface waters shall not contain concentrations of chemical constituents in amounts that adversely affect any designated beneficial use.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

California Toxics Rule (CTR) lists criterion maximum concentrations for silver to protect aquatic life in freshwater (1-hour average). The silver criterion in freshwater is hardness dependent for each sample and varies based on the ambient hardness during sampling. Section (b)(1) in CTR contains the hardness dependent formula for the metals criterion. If no hardness data were available, a value of 100 mg/L was used.

Guideline 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

Spatial Representation:

Samples were collected from San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam) from three sample stations: SG-R12, SJC-R2 and SG-R2.

Temporal Representation:

Samples were collected monthly from June 2006 through May of 2010.

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	138298	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Thallium
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 138298, Thallium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255754

Pollutant:

Thallium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA Quality Criteria for Water (Gold Book) states that thallium chronic toxicity to one species of fish occurs at concentrations as low as 20 ug/L after 2,600 hours of exposure. (USEPA, 1986)

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138298, Thallium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255769

Pollutant:

Thallium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA Quality Criteria for Water (Gold Book) states that thallium chronic toxicity to one species of fish occurs at concentrations as low as 20 ug/L after 2,600 hours of exposure. (USEPA, 1986)

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138298, Thallium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

256014

Pollutant:

Thallium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA Quality Criteria for Water (Gold Book) states that thallium chronic toxicity to one species of fish occurs at concentrations as low as 20 ug/L after 2,600 hours of exposure. (USEPA, 1986)

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138298, Thallium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255737

Pollutant:

Thallium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA Quality Criteria for Water (Gold Book) states that thallium chronic toxicity to one species of fish occurs at concentrations as low as 20 ug/L after 2,600 hours of exposure. (USEPA, 1986)

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138298, Thallium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255968

Pollutant:

Thallium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA Quality Criteria for Water (Gold Book) states that thallium chronic toxicity to one species of fish occurs at concentrations as low as 20 ug/L after 2,600 hours of exposure. (USEPA, 1986)

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138298, Thallium	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255990

Pollutant:

Thallium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The USEPA Quality Criteria for Water (Gold Book) states that thallium chronic toxicity to one species of fish occurs at concentrations as low as 20 ug/L after 2,600 hours of exposure. (USEPA, 1986)

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138299	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Toxaphene
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 138299, Toxaphene	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

256195

Pollutant:

Toxaphene

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Toxaphene. Although a total of 4 samples were collected, 4 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The toxaphene criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.0002 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

Data for this waterbody were collected over the date range 2011-08-10 to 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138299, Toxaphene	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255740

Pollutant:

Toxaphene

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Toxaphene. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The toxaphene criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.0002 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

Data for this waterbody were collected over the date range 2019-08-07 to 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138299, Toxaphene	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

256197

Pollutant:

Toxaphene

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 eSMR_San Jose Creek Water Reclamation Plant data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Toxaphene. Although a total of 4 samples were collected, 4 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold 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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The toxaphene criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.0002 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

Data for this waterbody were collected over the date range 2012-08-06 to 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138300	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

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:	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. 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. 0 of 32 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:	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 138300, Turbidity	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

256232

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: Waters shall be free of changes in turbidity that cause nuisance or adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Turbidities of 40 NTU or greater can cause a reduced foraging efficiency and a shift in prey selection in piscivorous fish (largemouth bass) due to interference with their ability to find prey (Shoup, D.E. and Wahl D.H., 2009).

Guideline Reference:

The Effects of Turbidity on Prey Selection by Piscivorous Largemouth Bass

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2015-08-05 and 2019-10-10

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138300, Turbidity	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

256199

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: Waters shall be free of changes in turbidity that cause nuisance or adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

The Effects of Turbidity on Prey Selection by Piscivorous Largemouth Bass

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2016-09-14 and 2019-12-18

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138300, Turbidity	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

256231

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: Waters shall be free of changes in turbidity that cause nuisance or adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

The Effects of Turbidity on Prey Selection by Piscivorous Largemouth Bass

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2015-06-22 and 2020-01-13

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138300, Turbidity	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

252855

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Turbidity.

Data Reference:

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: Waters shall be free of changes in turbidity that cause nuisance or adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

The Effects of Turbidity on Prey Selection by Piscivorous Largemouth Bass

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2015-12-14 and 2016-02-04

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138300, Turbidity	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

268100

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: Waters shall be free of changes in turbidity that cause nuisance or adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

The Effects of Turbidity on Prey Selection by Piscivorous Largemouth Bass

Spatial Representation:

The samples were collected at 1 monitoring site: SMC16832 (SGMR16832).

Temporal Representation:

The samples were collected between the dates of 2018-07-10 and 2018-07-10

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138300, Turbidity	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

268213

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: Waters shall be free of changes in turbidity that cause nuisance or adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

The Effects of Turbidity on Prey Selection by Piscivorous Largemouth Bass

Spatial Representation:

The samples were collected at 1 monitoring site: SMC00574 (SGMR00574).

Temporal Representation:

The samples were collected between the dates of 2017-05-03 and 2017-05-03

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.


DECISION ID	138272	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	alpha-Endosulfan (Endosulfan 1)
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 138272, alpha-Endosulfan (Endosulfan 1)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254530

Pollutant:

alpha-Endosulfan (Endosulfan 1)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The endosulfan I (alpha-endosulfan) criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.056 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138272, alpha-Endosulfan (Endosulfan 1)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254602

Pollutant:

alpha-Endosulfan (Endosulfan 1)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The endosulfan I (alpha-endosulfan) criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.056 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138272, alpha-Endosulfan (Endosulfan 1)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254575

Pollutant:

alpha-Endosulfan (Endosulfan 1)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The endosulfan I (alpha-endosulfan) criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.056 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138290	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	beta-Endosulfan (Endosulfan 2)
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 138290, beta-Endosulfan (Endosulfan 2)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254351

Pollutant:

beta-Endosulfan (Endosulfan 2)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The endosulfan II (beta-endosulfan) criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.056 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2019-02-20

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138290, beta-Endosulfan (Endosulfan 2)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254445

Pollutant:

beta-Endosulfan (Endosulfan 2)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The endosulfan II (beta-endosulfan) criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.056 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-08-10 and 2015-08-05

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138290, beta-Endosulfan (Endosulfan 2)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

254403

Pollutant:

beta-Endosulfan (Endosulfan 2)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The endosulfan II (beta-endosulfan) criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.056 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2019-08-07 and 2019-08-07

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program


DECISION ID	138293	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

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. 1 line of evidence is available in the administrative record to assess this pollutant. 9 of 310 samples exceeded 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. 9 of 310 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:	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 138293, pH	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

87824

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

241

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Seven of 241 samples exceeded the objective.

Data Reference:

Data for Various Pollutants in Various Water Bodies in Sanitation Districts of Los Angeles County, 2005-2010.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The pH of all inland surface waters shall not be depressed below 6.5 or raised above 8.5 as a result of waste discharges.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected from the SG-R2 and SG-R12 stations.

Temporal Representation:

Samples were collected approximately once a month from July 2005 to November 2009.

Environmental Conditions:

QAPP Information:

NPDES quality assurance.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 138293, pH	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

252743

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

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 LA County MS4 data for Pacific Ocean Shoreline, Laguna Beach HSA, at Dumond Drive at Victoria Beach to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for pH.

Data Reference:

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Los Angeles Basin: the pH for inland surface waters, bays, or estuaries shall not be depressed below 6.5 or raised above 8.5 as a result of waste discharges.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2016-02-04 and 2016-02-04

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138293, pH	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255477

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Los Angeles Basin: the pH for inland surface waters, bays, or estuaries shall not be depressed below 6.5 or raised above 8.5 as a result of waste discharges.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742413 (RSW-006).

Temporal Representation:

The samples were collected between the dates of 2012-08-06 and 2020-01-13

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138293, pH	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

265292

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

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 San Gabriel River Regional Monitoring Program data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for pH.

Data Reference:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Los Angeles Basin: the pH for inland surface waters, bays, or estuaries shall not be depressed below 6.5 or raised above 8.5 as a result of waste discharges.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC16832 (SGMR16832).

Temporal Representation:

The samples were collected between the dates of 2018-07-10 and 2018-07-10

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

Line of Evidence (LOE) for Decision ID 138293, pH	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255474

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

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:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Los Angeles Basin: the pH for inland surface waters, bays, or estuaries shall not be depressed below 6.5 or raised above 8.5 as a result of waste discharges.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 742414 (RSW-007).

Temporal Representation:

The samples were collected between the dates of 2016-09-14 and 2019-12-16

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138293, pH	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

255547

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

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:

WQ data from the California Integrated Water Quality System (CIWQS) assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Los Angeles Basin: the pH for inland surface waters, bays, or estuaries shall not be depressed below 6.5 or raised above 8.5 as a result of waste discharges.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 744616 (RSW-005).

Temporal Representation:

The samples were collected between the dates of 2011-06-06 and 2019-10-10

Environmental Conditions:

QAPP Information:

Los Angeles County Sanitation Districts. 2020. Los Angeles County Sanitation Districts Receiving Water Monitoring Program.

QAPP Information Reference(s):

Los Angeles County Sanitation Districts Receiving Water Monitoring Program

Line of Evidence (LOE) for Decision ID 138293, pH	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

265269

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

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:

Field, Habitat, Tissue, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Los Angeles Basin: the pH for inland surface waters, bays, or estuaries shall not be depressed below 6.5 or raised above 8.5 as a result of waste discharges.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SMC00574 (SGMR00574).

Temporal Representation:

The samples were collected between the dates of 2017-05-03 and 2017-05-03

Environmental Conditions:

QAPP Information:

Aquatic Bioassay & Consulting Laboratories. 2019. San Gabriel River Regional Monitoring Program.

QAPP Information Reference(s):


DECISION ID	153903	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Aluminum
Final Listing Decision:	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
Sources:	A Source Unknown
Expected TMDL Completion Date:	2037
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	During the 2024 cycle, the 1988 National Recommended Water Quality Criteria used to assess aluminum data was replaced with U.S. EPA’s 2018 Final Recommended Aquatic Life Criteria for Aluminum in Freshwater. This pollutant is being considered for removal from the CWA section 303(d) List under section 3.1 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. Four lines of evidence are available in the administrative record to assess pollutant. LOE 87905 for this waterbody-pollutant combination from a previous cycle was reviewed, determined to be inaccurate, and removed. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of 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. Eleven of 22 samples exceed the criteria and this exceeds 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 be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.

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 153903, Aluminum	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

2461

Pollutant:

Aluminum

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Twelve samples at this location were collected.

Summary of Results for the 2000-2001 Routine Monitoring at the San Gabriel River (Table B-5) (LACDPW, 2004c).

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

There is no applicable water quality guideline for this pollutant in this water body for the assigned beneficial use.

Objective/Criterion Reference:

Data for Various Pollutants in Los Angeles County Flood Control District, 2006-2010.

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The San Gabriel River Monitoring Station is located at an historic stream gauge station (Stream Gauge No. F263C-R), below San Gabriel River Parkway in Pico Rivera. At this location the upstream tributary area is 450 square miles. The San Gabriel River, at the gauging station, is a grouted rock-concrete stabilizer along the western levee and a natural section on the eastern side. Flow measurement and water sampling are conducted in the grouted rock area along the western levee of the river. The length of the concrete stabilizer is nearly 70 feet. The San Gabriel River sampling location has been an active stream gauging station since 1968.

Temporal Representation:

Samples taken between 10/28/2000 and 4/30/2003.

Environmental Conditions:

Samples taken on 10/10/2002 and 4/30/2003 were dry weather samples. All others were wet weather sampels.

QAPP Information:

Detailed QA/QC contained in this report.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 153903, Aluminum	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

314996

Pollutant:

Aluminum

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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 Los Angeles County Flood Control District_2010 data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support and results are as follows: 11 of 20 samples exceeded the water quality threshold for Aluminum.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The aluminum criterion for the protection of aquatic life, is pH, total hardness, and dissolved organic carbon (DOC) dependent. When total hardness or DOC data were not available, default values based on the level III ecoregions developed by U.S EPA were substituted (EPA, 2018). When pH data were not available, the median pH value for the ecoregion, a pH value from a comparable waterbody, or a pH value from a local study in the same waterbody was used as a comparable surrogate.

Guideline Reference:

Final Aquatic Life Ambient Water Quality Criteria for Aluminum. EPA-822-R-18-001. Washington, D.C.: Office of Water, USEPA.

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2006-12-09 and 2010-03-23

Environmental Conditions:

QAPP Information:

Data was previously assessed without a QAPP. Data reassessed without a QAPP for consistency.

QAPP Information Reference(s):

This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

Line of Evidence (LOE) for Decision ID 153903, Aluminum	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

314983

Pollutant:

Aluminum

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 Los Angeles County Flood Control District_2010 data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support and results are as follows: 0 of 20 samples exceeded the water quality threshold for Aluminum.

Data Reference:

Data for Various Pollutants in Los Angeles County Flood Control District, 2006-2010.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Final Aquatic Life Ambient Water Quality Criteria for Aluminum. EPA-822-R-18-001. Washington, D.C.: Office of Water, USEPA.

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2006-12-09 and 2010-03-23

Environmental Conditions:

QAPP Information:

Data was previously assessed without a QAPP. Data reassessed without a QAPP for consistency.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 153903, Aluminum	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

314921

Pollutant:

Aluminum

LOE Subgroup:

Pollutant-Water

Matrix:

Water

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 LA County MS4 data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Aluminum.

Data Reference:

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Final Aquatic Life Ambient Water Quality Criteria for Aluminum. EPA-822-R-18-001. Washington, D.C.: Office of Water, USEPA.

Spatial Representation:

The samples were collected at 1 monitoring site: S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the dates of 2015-12-14 and 2016-02-04

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4.


DECISION ID	150326	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Indicator Bacteria
Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	Delist from 303(d) list (being addressed by USEPA approved TMDL)(2018)
Revision Status	Revised
Sources:	See TMDL documentation
TMDL Name:	San Gabriel River Coliform (45)
TMDL Project Code:	391
Date TMDL Approved by USEPA:	06/14/2016
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 3.3 and 3.11 of the Listing Policy. Under section 3.3 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. Because a statistically sufficient number of geomean samples were not available, attainment of the bacteria objective was determined based only on the STV per the situation-specific weight of evidence approach outlined in Section 3.11 of the Listing Policy. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification for 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. 6 of 7 samples exceeded the statistical threshold value for E. coli and this exceeds 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 be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.

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 150326, Indicator Bacteria	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

303031

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

STV

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed LA County MS4 data for San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam to determine beneficial use support and the results are as follows: 6 of the 7 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The bacteria water quality objective to protect the REC-1 beneficial use where the salinity is less than 1 parts per thousand 95 percent or more of the time applies a statistical threshold value to E. coli of 320 cfu/100 mL, not to be exceeded by more than 10 percent of samples within a calendar month (ISWEBE 2018).

Objective/Criterion Reference:

Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): S14 (San Gabriel River @ San Gabriel River Parkway mass emission station).

Temporal Representation:

The samples were collected between the days of 2015-12-14 and 2018-09-20 .

Environmental Conditions:

QAPP Information:

Municipal Separate Storm Sewer System (MS4)

QAPP Information Reference(s):

Data for Various Pollutants in Various Water Bodies in Sanitation Districts of Los Angeles County, 2005-2010.

Line of Evidence (LOE) for Decision ID 150326, Indicator Bacteria	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

87917

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Two of the 64 samples exceeded the E. coli objective.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The E. coli density shall not exceed 235/100 ml. (Water Quality Control Plan for the Los Angeles Region).

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Ambient Water Quality Criteria for Bacteria - 1986. EPA440/5-84-002

Spatial Representation:

The samples were collected at San Jose Creek Station RSW-005 (Station R-2)and San Jose Creek Station RSW-006 (Station R-12). Station LC-R3 was moved to Reach 1. mapping change requested.

Temporal Representation:

The samples were collected once a month from June 2005 to May 2010.

Environmental Conditions:

QAPP Information:

The samples were collected under the San Jose Creek Laboratory sample collection procedures. Dec 28, 2010.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 150326, Indicator Bacteria	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

2460

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Sixteen out of 16 samples at this location exceeded the objective for fecal coliform (LACDPW, 2004c).

Summary of Results for the 2000-2001 Routine Monitoring at the San Gabriel River (Table B-5)

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

"In waters designated for contact recreation (REC-1), the fecal coliform concentration shall not exceed a log mean of 200/100 ml"
From the LA Regional Water Quality Control Board's Basin Plan

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Temporal Representation:

Samples taken between 10/28/2000 and 4/30/2003

Environmental Conditions:

Samples taken on 10/10/2002 and 4/30/2003 were 'DRY' samples. All others were 'WET'.

QAPP Information:

Detailed QA/QC contained in this report.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 150326, Indicator Bacteria	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

25339

Pollutant:

Indicator Bacteria

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

Other Agencies/Organizations provided monitoring data

Data Used to Assess Water Quality:

13 of 20 samples exceeded the Basin Plan single sample water quality objectives for indicator bacteria in fresh water and one of one sample exceeded the Basin Plan geometric mean water quality objective. Water quality samples were taken and analyzed for nitrite-nitrogen in accordance with the Municipal Separate Storm Sewer System (MS4) permit monitoring and testing parameters.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan bacteria objectives state that to protect water contact recreation in fresh waters individual samples shall not exceed the following limits: fecal coliform density shall not exceed 400/100 ml; and E. coli density shall not exceed 235/100 ml. The bacteria objectives also establish that the geometric means of individual samples shall not exceed the following limits: the fecal coliform density shall not exceed 200/100 ml; and the E. coli density shall not exceed 126/100 ml, as a geometric mean. The bacteria objectives are found in Attachment A of Regional Board Resolution No. 2001-018.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Temporal Representation:

Grab samples were taken approximately six times per year (four wet-weather events and two dry-weather events), from October 2003 through April 2007.

Environmental Conditions:

QAPP Information:

Data was collected in compliance with the sampling and monitoring procedures detailed in County of Los Angeles MS4 Permit (NPDES No. CAS004001) Monitoring and Reporting Program.

QAPP Information Reference(s):


DECISION ID	72689	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

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	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	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. 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. 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 18 samples exceeded the California Code of Regulations primary MCL for nitrite as nitrogen and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. 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 72689, Nitrogen, Nitrite	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

25324

Pollutant:

Nitrogen, Nitrite

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Freshwater Replenishment | Preservation of Rare & Endangered Species | Wildlife Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

One of 18 samples exceeded the California Code of Regulations primary MCL for nitrite as nitrogen. Water quality samples were taken and analyzed for nitrite-nitrogen in accordance with the Municipal Separate Storm Sewer System (MS4) permit monitoring and testing parameters.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Code of Regulations' Table 64431-A lists a maximum contamination level (Primary MCL) of 1.0 mg/L for Nitrite as Nitrogen (NO2-N) to protect drinking water sources.

Objective/Criterion Reference:

California Code of Regulations, Title 22, Division 4, Chapter 15. Domestic Water Quality and Monitoring

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Temporal Representation:

Grab samples were taken approximately six times per year (four wet-weather events and two dry-weather events), from October 2003 through April 2007.

Environmental Conditions:

QAPP Information:

Data was collected in compliance with the sampling and monitoring procedures detailed in County of Los Angeles MS4 Permit (NPDES No. CAS004001) Monitoring and Reporting Program.

QAPP Information Reference(s):


DECISION ID	98460	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Nitrogen, ammonia (Total 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	Original
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. 1 line of evidence is available in the administrative record to assess this pollutant. 0 of 217 samples exceeded the CRITERIA. 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. 0 of 217 samples exceeded the CRITERIA 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. 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 98460, Nitrogen, ammonia (Total Ammonia)	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

87817

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

217

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

Data for Various Pollutants in Various Water Bodies in Sanitation Districts of Los Angeles County, 2005-2010.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected at monitoring stations San Jose Creek R2 (SG-R2), and San Jose Creek R12 (SG-R12).

Temporal Representation:

Samples were collected from June 2005 to October 2009. Samples at SG-R2 were collected weekly.

Environmental Conditions:

QAPP Information:

Samples were collected as part of an NPDES permit requirement. Receiving water data collected to represent the water body as a whole. No QAPP was submitted but an unsigned field manual was.

QAPP Information Reference(s):


DECISION ID	68166	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

Pollutant:	Total Dissolved Solids
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:	This pollutant is being considered for placement on the 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. One line of evidence is available in the administrative record to assess this pollutant. One sample exceed the TDS water quality 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 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. One of 21 samples exceeded the TDS water quality objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. 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 68166, Total Dissolved Solids	Region 4
San Gabriel River Reach 2 (Firestone to Whittier Narrows Dam

LOE ID:

2464

Pollutant:

Total Dissolved Solids

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

One out of 21 samples at this location exceeded the objective for TDS (LACDPW, 2004c).

Summary of Results for the 2000-2001 Routine Monitoring at the San Gabriel River (Table B-5)

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

750 mg/L (from the LARWQCB Basin Plan, Table 3-8, "Water Quality Objectives for Selected Constituents in Inland Surface Waters")

Objective/Criterion Reference: