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

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Table 3-8 states that the Sulfates maximum concentration objective above Potrero Rd. in the Calleguas Creek watershed is 250 mg/L.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The sample was collected from the Conejo Creek Random Site 916 station (408BA0916).

Temporal Representation:

The sample was collected on 5/8/2008.

Environmental Conditions:

QAPP Information:

SWAMP QAPP

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 136524, Sulfates	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

93917

Pollutant:

Sulfates

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:

State Water Board staff assessed SWAMP data for Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) to determine beneficial use support and results are as follows: 1 of 1 samples exceed the criterion for Sulfate.

Data Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Table 3-8 of The Water Quality Control Plan for the Los Angeles Region specifies the Sulfate objective for the Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) within the Calleguas-Conejo Creek watershed's Above Portrero Road reach boundary as 250 mg/L.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) was collected at 1 monitoring site [ Conejo Creek Random Site 836 - 408BA0836]

Temporal Representation:

Data was collected on a single day 5/7/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	136488	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Chlordane
Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Sources:	See TMDL documentation
TMDL Name:	Calleguas Creek Historic Pesticides (5)
TMDL Project Code:	358
Date TMDL Approved by USEPA:	03/24/2006
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal from the CWA section 303(d) List under sections 2.2, 4.5 and 4.1 of the Listing Policy. Under sections 4.5 and 4.1 of the Policy, a minimum of one line of evidence is needed to assess listing status. Four lines of evidence are available in the administrative record to assess this pollutant. LOEs 256039 and 255976 are for the total fraction (confirmed with data provider) and are being manually added to LOE 267406 for total chlordane. 0 of 3 samples exceeded the criteria for chlordane in water. 2 of 2 samples exceeded the guideline for chlordane in fish tissue. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the CWA section 303(d) List. There is sufficient justification to place it in the Being Addressed portion of the CWA 303(d) List because a TMDL has been completed and approved by RWQCB and USEPA, and is expected to result in attainment of the standard. 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. 2 of 2 samples exceeded the guideline and this exceeds the allowable exceedances in Table 4.1 of the Listing Policy. 4. The TMDL for Organochlorine (OC) Pesticides, Polychlorinated Biphenyls (PCBs) and Siltation in Calleguas Creek, Its Tributaries, and Mugu Lagoon was approved by USEPA on March 24, 2006. 5. 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 not be removed from the section 303(d) list because applicable water quality standards for the pollutant are being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

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 136488, Chlordane	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255976

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_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Total Chlordane.

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:

Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 767698 (RSW-002D).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136488, Chlordane	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

256039

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:

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: 767697 (RSW-001U).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136488, Chlordane	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2052

Pollutant:

Chlordane

LOE Subgroup:

Pollutant-Tissue

Matrix:

Tissue

Fraction:

Total

Beneficial Use:

Commercial or recreational collection of fish, shellfish, or organisms

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fish tissue analysis

Data Used to Assess Water Quality:

Two tissue samples, 2 samples exceeding (TSMP, 2002).

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Los Angeles RWQCB Basin Plan: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

OEHHA Screening Value: 30 ug/kg (Brodberg and Pollock, 1999). Section 6.1.3 of the Listing Policy does not allow the use of MTRLs to evaluate fish and shellfish tissue data.

Guideline Reference:

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

Spatial Representation:

Sample was collected spatially.

Temporal Representation:

One-time sample.

Environmental Conditions:

QAPP Information:

TSMP

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 136488, Chlordane	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

267406

Pollutant:

Chlordane

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:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	136491	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Chlorpyrifos
Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)(2018)
Revision Status	Revised
Sources:	A Source Unknown
TMDL Name:	Calleguas Creek Toxicity (2)
TMDL Project Code:	355
Date TMDL Approved by USEPA:	03/14/2006
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal on the CWA section 303(d) List under sections 2.2 and section 4.1of the Listing Policy. Under section 4.1 of the Policy, a minimum of one line of evidence is needed 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 removing this water segment-pollutant combination from the CWA section 303(d) List. There is sufficient justification to place it in the Being Addressed portion of the CWA 303(d) List because a TMDL has been completed and approved by RWQCB and USEPA, and is expected to result in attainment of the standard. 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. 3 of 6 samples exceeded the criterion and these exceed the allowable frequency listed in Table 4.1 of the Listing Policy. 4. The Calleguas Creek Toxicity TMDL was approved by USEPA on 03/14/2006. 5. 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 not be removed from the section 303(d) list because applicable water quality standards for the pollutant are being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

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 136491, Chlorpyrifos	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

258483

Pollutant:

Chlorpyrifos

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 RWB4 So. CA Stormwater Monitoring Coalition data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) 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:

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

Data for this waterbody were collected over the date range 2014-06-04 to 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136491, Chlorpyrifos	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

253876

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_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 3 of 5 samples exceeded the water quality threshold for Chlorpyrifos.

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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2019-08-07

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136491, Chlorpyrifos	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

253855

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:

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2018-05-02 and 2018-05-02

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136491, Chlorpyrifos	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2061

Pollutant:

Chlorpyrifos

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Unspecified--This LOE is a placeholder to support a 303(d) listing decision made by USEPA for 2006.

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:

Temporal Representation:

Environmental Conditions:

QAPP Information:

QA Info Missing

QAPP Information Reference(s):


DECISION ID	149492	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	DDT (Dichlorodiphenyltrichloroethane)
Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Sources:	See TMDL documentation
TMDL Name:	Calleguas Creek Historic Pesticides (5)
TMDL Project Code:	358
Date TMDL Approved by USEPA:	03/24/2006
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal from the CWA section 303(d) List under sections 2.2, 4.5 and 4.1 of the Listing Policy. Under sections 4.5 and 4.1 of the Policy, a minimum of one line of evidence is needed to assess listing status. Four lines of evidence are available in the administrative record to assess this pollutant. LOE 259972 and LOEs 254143 and 254146 are all for the total fraction and are being manually added together. 4 of 4 samples exceed the guideline for DDT in fish tissue. 0 of 2 sample exceeded the criteria for DDT in water. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the CWA section 303(d) List. There is sufficient justification to place it in the Being Addressed portion of the CWA 303(d) List because a TMDL has been completed and approved by RWQCB and USEPA, and is expected to result in attainment of the standard. 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. 4 of 4 samples exceeded the guideline and this exceeds the allowable exceedances in Table 4.1 4. The TMDL for Organochlorine (OC) Pesticides, Polychlorinated Biphenyls (PCBs) and Siltation in Calleguas Creek, Its Tributaries, and Mugu Lagoon was approved by USEPA on March 24, 2006. 5. 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 not be removed from the section 303(d) list because applicable water quality standards for the pollutant are being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

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 149492, DDT (Dichlorodiphenyltrichloroethane)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254146

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:

Data Reference:

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: 767698 (RSW-002D).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 149492, DDT (Dichlorodiphenyltrichloroethane)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254143

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:

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: 767697 (RSW-001U).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 149492, DDT (Dichlorodiphenyltrichloroethane)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

259972

Pollutant:

DDT (Dichlorodiphenyltrichloroethane)

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 RWB4 So. CA Stormwater Monitoring Coalition data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) 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:

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

Data for this waterbody were collected over the date range 2014-06-04 to 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 149492, DDT (Dichlorodiphenyltrichloroethane)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2055

Pollutant:

DDT (Dichlorodiphenyltrichloroethane)

LOE Subgroup:

Pollutant-Tissue

Matrix:

Tissue

Fraction:

Total

Beneficial Use:

Commercial or recreational collection of fish, shellfish, or organisms

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fish tissue analysis

Data Used to Assess Water Quality:

Four out of 4 samples exceeded. A total of 4 whole fish composite samples of fathead minnow and mosquitofish were collected. Two fathead minnow samples were collected in 1992. Two mosquitofish samples were collected in 1998. The guideline was exceeded in all samples (TSMP, 2002).

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Los Angeles RWQCB Basin Plan: Toxic pollutants shall not be present at levels that will bioaccumulate in aquatic life to levels which are harmful to aquatic life or human health.

Objective/Criterion Reference:

Evaluation Guideline:

1000 ng/g - NAS Guideline (whole fish).

Guideline Reference:

Spatial Representation:

One station located at Rancho Road crossing south west of Camarillo.

Temporal Representation:

Samples were collected in 6/2/92 and 6/25/98.

Environmental Conditions:

QAPP Information:

Toxic Substances Monitoring Program 1992-93 Data Report.

Environmental Chemistry Quality Assurance and Data Report for the Toxic Substances Monitoring Program,1996-2000. Department of Fish and Game

QAPP Information Reference(s):


DECISION ID	136498	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Diazinon
Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)(2018)
Revision Status	Revised
Sources:	A Source Unknown
TMDL Name:	Calleguas Creek Toxicity (2)
TMDL Project Code:	355
Date TMDL Approved by USEPA:	03/14/2006
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal on the CWA section 303(d) List under sections 2.2 and section 4.1 of the Listing Policy. Under section 4.1 of the Policy, a minimum of one line of evidence is needed to assess listing status. Three lines of evidence are available in the administrative record to assess this pollutant. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the CWA section 303(d) List. There is sufficient justification to place it in the Being Addressed portion of the CWA 303(d) List because a TMDL has been completed and approved by RWQCB and USEPA, and is expected to result in attainment of the standard. 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 and 0 of 1 sample exceeded the criteria and this is insufficient to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. A minimum of 28 samples is needed to determine if a beneficial use is fully supported using table 4.1. 4. The Calleguas Creek Toxicity TMDL was approved by USEPA on 03/14/2006. 5. 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 not be removed from the section 303(d) list because there was a previous listing and there are not enough data to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy.

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 136498, Diazinon	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2062

Pollutant:

Diazinon

LOE Subgroup:

Pollutant-Water

Matrix:

Not Specified

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Unspecified--This LOE is a placeholder to support a listing decision made by USEPA for 2006.

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:

Temporal Representation:

Environmental Conditions:

QAPP Information:

QA Info Missing

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 136498, Diazinon	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254518

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:

Water Board staff assessed eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Diazinon.

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 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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2018-05-02 and 2019-05-01

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136498, Diazinon	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254473

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2018-05-02 and 2018-05-02

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136498, Diazinon	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

260028

Pollutant:

Diazinon

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	136499	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Dieldrin
Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Sources:	See TMDL documentation
TMDL Name:	Calleguas Creek Historic Pesticides (5)
TMDL Project Code:	358
Date TMDL Approved by USEPA:	03/24/2006
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal from the CWA section 303(d) List under sections 2.2, 4.5 and 4.1 of the Listing Policy. Under sections 4.5 and 4.1 of the Policy, a minimum of one line of evidence is needed to assess listing status. Four lines of evidence are available in the administrative record to assess this pollutant. LOE 260606 and LOEs 254593 and 254690 are equivalent fractions and are being manually added. 2 of 2 samples exceeded the guideline for dieldrin in fish tissue. 0 of 3 samples exceeded the criteria for dieldrin in water. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the CWA section 303(d) List. There is sufficient justification to place it in the Being Addressed portion of the CWA 303(d) List because a TMDL has been completed and approved by RWQCB and USEPA, and is expected to result in attainment of the standard. 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. 2 of 2 samples exceeded the guideline and this exceeds the allowable exceedances in Table 4.1. 4. The TMDL for Organochlorine (OC) Pesticides, Polychlorinated Biphenyls (PCBs) and Siltation in Calleguas Creek, Its Tributaries, and Mugu Lagoon was approved by USEPA on March 24, 2006. 5. 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 not be removed from the section 303(d) list because applicable water quality standards for the pollutant are being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

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 136499, Dieldrin	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254593

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: 767698 (RSW-002D).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136499, Dieldrin	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2048

Pollutant:

Dieldrin

LOE Subgroup:

Pollutant-Tissue

Matrix:

Tissue

Fraction:

Total

Beneficial Use:

Commercial or recreational collection of fish, shellfish, or organisms

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fish tissue analysis

Data Used to Assess Water Quality:

Two tissue samples, 2 samples exceeding (TSMP, 2002).

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Los Angeles RWQCB Basin Plan: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

OEHHA Screening Value: 2.0 ug/kg (Brodberg and Pollock, 1999). Section 6.1.3 of the Listing Policy does not allow the use of MTRLs to evaluate fish and shellfish tissue data.

Guideline Reference:

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

Spatial Representation:

Sample was collected spatially.

Temporal Representation:

One-time sample.

Environmental Conditions:

QAPP Information:

TSMP QAPP.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 136499, Dieldrin	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254690

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:

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: 767697 (RSW-001U).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136499, Dieldrin	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

260606

Pollutant:

Dieldrin

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	136507	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Sources:	See TMDL documentation
TMDL Name:	Calleguas Creek Historic Pesticides (5)
TMDL Project Code:	358
Date TMDL Approved by USEPA:	03/24/2006
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal from the CWA section 303(d) List under sections 2.2, 4.5 and 4.1 of the Listing Policy. Under sections 4.5 and 4.1 of the Policy, a minimum of one line of evidence is needed to assess listing status. Five lines of evidence are available in the administrative record to assess this pollutant. LOE 30131 relies on a narrative objective; during development of the TMDL for OC Pesticides and PCBs in the Calleguas Creek Watershed, this waterbody was shown to be impaired for gamma-HCH in fish tissue. 0 of 2 samples exceeded the guideline for gamma-HCH in fish tissue. LOE 262180, 254727 and 254752 consider data for the total fraction and are being manually summed. 0 of 3 samples exceeded the criterion for gamma-HCH in water. Based on the readily available data and information, the weight of evidence indicates that there is insufficient justification for removing this water segment-pollutant combination from the CWA section 303(d) List. There is sufficient justification to place it in the Being Addressed portion of the CWA 303(d) List because a TMDL has been completed and approved by RWQCB and USEPA, and is expected to result in attainment of the standard. 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 2 samples exceeded the guideline and 0 of 3 samples exceeded the criterion and this information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating when a previous determination was made for impairment. 4. The TMDL for Organochlorine (OC) Pesticides, Polychlorinated Biphenyls (PCBs) and Siltation in Calleguas Creek, Its Tributaries, and Mugu Lagoon was approved by USEPA on March 24, 2006. 5. 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 not be removed from 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 after a previous listing.

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 136507, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2053

Pollutant:

Lindane/gamma Hexachlorocyclohexane (gamma-HCH)

LOE Subgroup:

Pollutant-Tissue

Matrix:

Tissue

Fraction:

Total

Beneficial Use:

Commercial or recreational collection of fish, shellfish, or organisms

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fish tissue analysis

Data Used to Assess Water Quality:

Two tissue samples with no samples exceeding the screening value (TSMP, 2002).

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Los Angeles RWQCB Basin Plan: Toxic pollutants shall not be present at levels that will bioaccumulate in aquatic life to levels which are harmful to aquatic life or human health.

Objective/Criterion Reference:

Evaluation Guideline:

OEHHA Screening Value: 30 ug/kg for Lindane (gamma-HCH) (Brodberg and Pollock, 1999). Section 6.1.3 of the Listing Policy does not allow the use of MTRLs to evaluate fish and shellfish tissue data.

Guideline Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Spatial Representation:

Sample was collected spatially.

Temporal Representation:

One-time sample.

Environmental Conditions:

QAPP Information:

TSMP

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 136507, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

30131

Pollutant:

Lindane/gamma-Hexachlorocyclohexane (gamma-HCH) (tissue)

LOE Subgroup:

Narrative Description Data

Matrix:

Not Specified

Fraction:

None

Beneficial Use:

Commercial or recreational collection of fish, shellfish, or organisms

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

A TMDL has been approved for this water segment-pollutant combination. The Calleguas Creek OC Pesticides and PCBs TMDL was adopted by the Los Angeles RWQCB on July 07, 2005 and subsequently approved by USEPA on March 24, 2006. The TMDL was integrated into the Basin Plan as Attachment A of Regional Board Resolution No. 2006-010.

Data Reference:

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 136507, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254727

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: 767698 (RSW-002D).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136507, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

262180

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:

Data Reference:

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136507, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254752

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: 767697 (RSW-001U).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136521	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	PCBs (Polychlorinated biphenyls)
Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Sources:	See TMDL documentation
TMDL Name:	Calleguas Creek Historic Pesticides (5)
TMDL Project Code:	358
Date TMDL Approved by USEPA:	03/24/2006
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal from the CWA section 303(d) List under sections 2.2, 4.5 and 4.1 of the Listing Policy. Under sections 4.5 and 4.1 of the Policy, a minimum of one line of evidence is needed to assess listing status. Three lines of evidence are available in the administrative record to assess this pollutant. 0 of 2 samples exceeded the criteria for PCBs in water. 2 of 2 samples exceeded the guideline for PCBs in fish tissue Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the CWA section 303(d) List. There is sufficient justification to place it in the Being Addressed portion of the CWA 303(d) List because a TMDL has been completed and approved by RWQCB and USEPA, and is expected to result in attainment of the standard. 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. 2 of 2 samples exceeded the guideline and these exceed the allowable frequency listed in Table 4.1 of the Listing Policy. 4. The TMDL for Organochlorine (OC) Pesticides, Polychlorinated Biphenyls (PCBs) and Siltation in Calleguas Creek, Its Tributaries, and Mugu Lagoon was approved by USEPA on March 24, 2006. 5. 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 not be removed from the section 303(d) list because applicable water quality standards for the pollutant are being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

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 136521, PCBs (Polychlorinated biphenyls)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255660

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:

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 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: 767697 (RSW-001U).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136521, PCBs (Polychlorinated biphenyls)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255422

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:

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: 767698 (RSW-002D).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136521, PCBs (Polychlorinated biphenyls)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2050

Pollutant:

PCBs (Polychlorinated biphenyls)

LOE Subgroup:

Pollutant-Tissue

Matrix:

Tissue

Fraction:

Total

Beneficial Use:

Commercial or recreational collection of fish, shellfish, or organisms

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fish tissue analysis

Data Used to Assess Water Quality:

Two composite tissue samples, 2 samples exceeding (TSMP, 2002).

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Los Angeles RWQCB Basin Plan: Toxic pollutants shall not be present at levels that will bioaccumulate in aquatic life to levels which are harmful to aquatic life or human health.

Objective/Criterion Reference:

Evaluation Guideline:

OEHHA Screening Value: 20 ug/kg (Brodberg and Pollock, 1999). Section 6.1.3 of the Listing Policy does not allow the use of MTRLs to evaluate fish and shellfish tissue data.

Guideline Reference:

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

Spatial Representation:

Samples were collected spatially.

Temporal Representation:

One-time sample.

Environmental Conditions:

QAPP Information:

TSMP

QAPP Information Reference(s):


DECISION ID	136527	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Total Dissolved Solids
Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)(2018)
Revision Status	Revised
Sources:	Atmospheric Deposition \| Domestic Use of Ground Water \| Groundwater Loadings \| Major Municipal Point Source-dry weather discharge \| Surface Runoff
TMDL Name:	Calleguas Creek Boron/Sulfate/TDS (4)
TMDL Project Code:	357
Date TMDL Approved by USEPA:	12/02/2008
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal on the CWA section 303(d) List under sections 2.2 and 4.2 of the Listing Policy. Under section 4.2 of the Policy, a minimum of one line of evidence is needed to assess listing status. 2 lines of evidence are available in the administrative record to assess this pollutant. 1 of the 1 samples exceeded the OBJECTIVE. 54 of the 65 samples exceeded the OBJECTIVE. LOEs 4065 and 28029 are placeholders from previous decisions not held in this assessment database. They will not be used for assessment because other data are sufficient to assess beneficial use support. Based on the readily available data and information, the weight of evidence indicates that there is insufficient justification for removing this water segment-pollutant combination from the CWA section 303(d) List. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the CWA section 303(d) List. There is sufficient justification to place it in the Being Addressed portion of the CWA 303(d) List because a TMDL has been completed and approved by RWQCB and USEPA, and is expected to result in attainment of the standard. 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. 54 of 65 samples exceeded the objective and this exceeds the allowable frequency listed in Table 4.2 of the Listing Policy. 4. The TMDL for Salts in the Calleguas Creek Watershed was approved by USEPA on 12/2/2008. 5. 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 not be removed from the section 303(d) list because applicable water quality standards for the pollutant are being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

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 136527, Total Dissolved Solids	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

243837

Pollutant:

Total Dissolved Solids

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Agricultural Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed data from the Camarillo Wastewater Reclamation Plant to determine beneficial use support. The results are as follows: 24 out of 32 samples exceed the criterion for Total Dissolved Solids.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region list a site specific objective for Total Dissolved Solids in the Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) of 850 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Station RSW-001U (34.193825, -119.001478), located in Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list).

Temporal Representation:

The water samples were taken between 8/2/2017 - 10/7/2020, per the monitoring requirements listed in the Camarillo Wastewater Reclamation Plant NPDES Permit monitoring and reporting program.

Environmental Conditions:

QAPP Information:

The work was performed in accordance with the Camarillo Wastewater Reclamation Plant NDPES Permit quality assurance provisions for water quality monitoring.

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136527, Total Dissolved Solids	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

243846

Pollutant:

Total Dissolved Solids

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Agricultural Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed data from the Camarillo Wastewater Reclamation Plant to determine beneficial use support. The results are as follows: 30 out of 32 samples exceed the criterion for Total Dissolved Solids.

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:

Station RSW-002D (34.192402, -119.003827), located in Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list).

Temporal Representation:

The water samples were taken between 8/2/2017 - 10/7/2020, per the monitoring requirements listed in the Camarillo Wastewater Reclamation Plant NPDES Permit monitoring and reporting program.

Environmental Conditions:

QAPP Information:

The work was performed in accordance with the Camarillo Wastewater Reclamation Plant NDPES Permit quality assurance provisions for water quality monitoring.

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136527, Total Dissolved Solids	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

28029

Pollutant:

Total Dissolved Solids

LOE Subgroup:

Narrative Description Data

Matrix:

Not Specified

Fraction:

None

Beneficial Use:

Agricultural Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

A TMDL has been approved for this water segment-pollutant combination. The Calleguas Creek Watershed Salts TMDL was adopted by the Los Angeles RWQCB on October 04, 2007 and subsequently approved by USEPA. The TMDL was integrated into the Basin Plan as Attachment A of Regional Board Resolution No. 2007-016.

Data Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

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 136527, Total Dissolved Solids	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

244214

Pollutant:

Total Dissolved Solids

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Agricultural Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed data from the Southern California Stormwater Monitoring Coalition to determine beneficial use support. The results are as follows: zero out of one samples exceed the criterion for Total Dissolved Solids.

Data Reference:

Field, Habitat, Toxicity, 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 lists a site specific objective for Total Dissolved Solids in Calleguas Creek Reach 9A of 850 mg/L

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Station 408BA0836 (34.1907194768, -119.005109779), located in Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list).

Temporal Representation:

Water samples were taken on 6/4/2014 for the Southern California Stormwater Monitoring Coalition.

Environmental Conditions:

QAPP Information:

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136527, Total Dissolved Solids	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

4065

Pollutant:

Total Dissolved Solids

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Agricultural Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

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

Data Reference:

Placeholder reference pre-2006 303(d)

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Unspecified

Objective/Criterion Reference:

Placeholder reference pre-2006 303(d)

Evaluation Guideline:

Unspecified

Guideline Reference:

Placeholder reference pre-2006 303(d)

Spatial Representation:

Unspecified

Temporal Representation:

Unspecified

Environmental Conditions:

Unspecified

QAPP Information:

Unspecified

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 136527, Total Dissolved Solids	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

93924

Pollutant:

Total Dissolved Solids

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:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Table 3-8 of The Water Quality Control Plan for the Los Angeles Region specifies the Dissolved Solids objective for the Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) within the Calleguas-Conejo Creek watershed's Above Portrero Road reach boundary as 850 mg/L.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) was collected at 1 monitoring site [ Conejo Creek Random Site 836 - 408BA0836]

Temporal Representation:

Data was collected on a single day 5/7/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	136528	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Toxaphene
Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Sources:	See TMDL documentation
TMDL Name:	Calleguas Creek Historic Pesticides (5)
TMDL Project Code:	358
Date TMDL Approved by USEPA:	03/24/2006
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal on the CWA section 303(d) List under sections 2.2, 4.1 and 4.5 of the Listing Policy. Under sections 4.1 and 4.5 of the Policy, a minimum of one line of evidence is needed to assess listing status. Three lines of evidence are available in the administrative record to assess this pollutant. 0 of 2 samples exceeded the criterion for toxaphene in water. 4 of 4 samples exceeded the guideline for toxaphene in fish tissue. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the CWA section 303(d) List. There is sufficient justification to place it in the Being Addressed portion of the CWA 303(d) List because a TMDL has been completed and approved by RWQCB and USEPA, and is expected to result in attainment of the standard. 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. 4 of 4 samples exceeded the guideline and these exceed the allowable frequency listed in Table NUMBER of the Listing Policy. 4. The TMDL for Organochlorine (OC) Pesticides, Polychlorinated Biphenyls (PCBs) and Siltation in Calleguas Creek, Its Tributaries, and Mugu Lagoon was approved by USEPA on March 24, 2006. 5. 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 not be removed from the section 303(d) list because applicable water quality standards for the pollutant are being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

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 136528, Toxaphene	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

256162

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:

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: 767698 (RSW-002D).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136528, Toxaphene	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2057

Pollutant:

Toxaphene

LOE Subgroup:

Pollutant-Tissue

Matrix:

Tissue

Fraction:

Total

Beneficial Use:

Commercial or recreational collection of fish, shellfish, or organisms

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fish tissue analysis

Data Used to Assess Water Quality:

Four out of 4 samples exceeded. Two whole fish composite samples of fathead minnow and 2 whole fish composite samples of mosquitofish were collected. Fathead minnow were collected in 1992. Mosquitofish were collected in 1998. The guideline was exceeded in all samples (TSMP, 2002).

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Los Angeles RWQCB Basin Plan: Toxic pollutants shall not be present at levels that will bioaccumulate in aquatic life to levels which are harmful to aquatic life or human health.

Objective/Criterion Reference:

Evaluation Guideline:

100 ng/g - NAS Guideline (Whole fish).

Guideline Reference:

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

Spatial Representation:

One station located at Rancho Road crossing south west of Camarillo.

Temporal Representation:

Samples were collected annually in 1992 and 1998.

Environmental Conditions:

QAPP Information:

Toxic Substances Monitoring Program 1992-93 Data Report.

Environmental Chemistry Quality Assurance and Data Report for the Toxic Substances Monitoring Program, 1996-2000. Department of Fish and Game.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 136528, Toxaphene	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255759

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:

Data Reference:

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: 767697 (RSW-001U).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136529	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Toxicity
Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)(2018)
Revision Status	Revised
Sources:	A Source Unknown
TMDL Name:	Calleguas Creek Toxicity (2)
TMDL Project Code:	355
Date TMDL Approved by USEPA:	03/14/2006
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 4.1 of the Listing Policy. Under section 4.1 a single line of evidence are necessary to assess listing status. 2 lines of evidence are available in the administrative record to assess this pollutant. 1 of the 2 samples exceeded the CRITERIA. 0 of the 0 samples exceeded the CRITERIA. Based on the readily available data and information, the weight of evidence indicates that there is insufficient 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. 1 of 2 and 0 of 0 samples exceeded the CRITERIA and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 28 samples is needed to determine if a beneficial use is fully supported using table 4.1. 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 not be removed from the section 303(d) list because there was a previous listing and there are not enough data to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy.

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 136529, Toxicity	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

244479

Pollutant:

Toxicity

LOE Subgroup:

Toxicity

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

TOXICITY TESTING

Data Used to Assess Water Quality:

1 of the 1 samples collected by RWB4 So. CA Stormwater Monitoring Coalition for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) exhibited toxicity. A sample may have multiple toxicity test results, but will only be counted once. A sample is defined as being collected on the same day and the same location. The following organisms and parameters were utilized for the toxicity tests: Ceriodaphnia dubia for Survival, Ceriodaphnia dubia for Young/female. The following tests exhibited toxicity: Ceriodaphnia dubia for Young/female on 2014-06-04.

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in, human, plant, animal, or aquatic life.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The sample is toxic when the response of the organisms exposed to the sample is significantly different (worse) than the response of the organisms exposed to the laboratory control based on statistical hypothesis testing. An exceedance is counted when the significant effect code is “Significant; Less Similarity,” which means that the sample result is significantly different than the control result, and the percent effect is greater than the evaluation threshold. The default evaluation threshold is 20% unless otherwise stated.

Guideline Reference:

Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms. Fourth Edition. Office of Water, U.S. Environmental Protection Agency. Washington, D.C. EPA-821-R-02-013

Spatial Representation:

The samples were collected at monitoring site: 408BA0836 ( Conejo Creek Random Site 836 ).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04.

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136529, Toxicity	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2063

Pollutant:

Toxicity

LOE Subgroup:

Toxicity

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Unspecified--This LOE is a placeholder to support a listing decision made by USEPA for 2006.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Temporal Representation:

Environmental Conditions:

QAPP Information:

QA Info Missing

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 136529, Toxicity	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

83494

Pollutant:

Toxicity

LOE Subgroup:

Toxicity

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

TOXICITY TESTING

Data Used to Assess Water Quality:

One sample was collected to evaluate water toxicity. The sample did not exhibit significant toxicity. The toxicity tests included survival and reproduction of Ceriodaphnia dubia. One sample can have multiple toxicity test results but will be counted only once. One sample is defined as being collected on the same day at the same location with the same lab sample id (if provided).

Data Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in, human, plant, animal, or aquatic life. Region 4 Basin Plan.

Objective/Criterion Reference:

Evaluation Guideline:

Toxicity is defined as a statistically significant effect in the sample exposure compared to the control using EPA-recommended hypothesis testing. For SWAMP data exceedances are counted with the significant effect code SL. SL is defined as the result being significant compared to the negative control based on a statistical test, less than stated the alpha level, AND less than the evaluation threshold.

Guideline Reference:

Spatial Representation:

The samples were collected at station 408BA0836.

Temporal Representation:

The samples were collected in May 2008.

Environmental Conditions:

QAPP Information:

Data quality is good. Data results were recorded in the SWAMP database and followed SWAMP protocols.

QAPP Information Reference(s):


DECISION ID	136542	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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 136542, 1,1,2-Trichloroethane	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

256092

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: 767697 (RSW-001U).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136542, 1,1,2-Trichloroethane	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

256280

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: 767698 (RSW-002D).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136536	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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 136536, Acrolein	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

253464

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: 767698 (RSW-002D).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136536, Acrolein	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

253377

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: 767697 (RSW-001U).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136538	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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 136538, Aldrin	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

256382

Pollutant:

Aldrin

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136538, Aldrin	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

253573

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: 767698 (RSW-002D).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136538, Aldrin	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

253289

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: 767697 (RSW-001U).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136539	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Alkalinity as CaCO3
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 136539, Alkalinity as CaCO3	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

256534

Pollutant:

Alkalinity as CaCO3

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136539, Alkalinity as CaCO3	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

93882

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:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan, Colorado River Basin).

Objective/Criterion Reference:

Evaluation Guideline:

The Alkalinity as CaCO3 criteria for the protection of freshwater aquatic life is 20000 ug/L (National Recommended Water Quality Criteria, 2009).

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) was collected at 1 monitoring site [ Conejo Creek Random Site 836 - 408BA0836]

Temporal Representation:

Data was collected on a single day 5/7/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 136539, Alkalinity as CaCO3	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

256535

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	153874	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Aluminum
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:	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. LOEs 93883 and have been replaced by LOEs 315180, respectively, due to a reassessment of data using the 2018 USEPA aluminum criteria. 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 153874, Aluminum	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

315180

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 RWB4_SMC_2008 data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Aluminum.

Data Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2008-05-07 and 2008-05-07

Environmental Conditions:

QAPP Information:

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 153874, Aluminum	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

315175

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:

Data Reference:

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 153874, Aluminum	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

315181

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:

Data Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2008-05-07 and 2008-05-07

Environmental Conditions:

QAPP Information:

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 153874, Aluminum	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

315030

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:

Data Reference:

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	150429	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Ammonia
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
TMDL Name:	Calleguas Creek Nitrogen (1)
TMDL Project Code:	228
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 are necessary to assess listing status. Four lines of evidence are available in the administrative record to assess this waterbody pollutant combination. 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 43 sample 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 150429, Ammonia	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

94374

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:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

Aquatic Life Ambient Water Quality Criteria for Ammonia ? Freshwater (USEPA 2013): the 30-day rolling average concentration (criterion continuous concentration or CCC) of total ammonia nitrogen(in mg TAN/L) in freshwater are not to be exceeded more than once every three years on average. The CCC values are based on pH and temperature. The CCC formula is found on page 46 and the table of CCC values is on page 49.

Guideline Reference:

Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013

Spatial Representation:

Data for this line of evidence for Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) was collected at 1 monitoring site [ Conejo Creek Random Site 836 - 408BA0836]

Temporal Representation:

Data was collected on a single day 5/7/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 150429, Ammonia	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

253488

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_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 23 samples exceeded the water quality threshold for Ammonia as N.

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 for ammonia, early life stages present, listed in the Basin Plan for the Los Angeles Region.

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-07/08.

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 150429, Ammonia	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

253489

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_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 18 samples exceeded the water quality threshold for Ammonia as N.

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 for ammonia, early stages present, listed in the Basin Plan for the Los Angeles Region.

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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-10-07

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 150429, Ammonia	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

257023

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

SWAMP Data:

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 for ammonia, with early life stages present, listed in the Basin Plan for the Los Angeles Region.

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The sample was collected on 2014-06-04.

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	136550	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Anatoxin-A
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 136550, Anatoxin-A	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

257079

Pollutant:

Anatoxin-A

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:

Data Reference:

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

SWAMP Data:

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 California Cyanobacteria and Harmful Algal Bloom (CCHAB) Network established 20 ug/L of anatoxin-A as the water concentration protective of swimmers and other contact recreational users including water-skiing/jet-skiing, fishing, boating, sail boarding, and canoeing.

Guideline Reference:

Appendix to the CCHAB preliminary changes to the statewide voluntary guidance on cyanoHABs in recreational waters, January 2016. Appendix A. Description of cyanotoxin triggers in recreational waters.

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	136483	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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:	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 136483, Antimony	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

253429

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:

Water Board staff assessed eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 4 samples exceeded the water quality threshold for Antimony.

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2018-08-01 and 2020-08-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136483, Antimony	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

253473

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:

Water Board staff assessed eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Antimony.

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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-08-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136484	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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. Four lines of evidence are available in the administrative record to assess this pollutant. The data provider has indicated that there was an error in the units for arsenic in LOE 253456. The original data file had results reported in both mg/L and ug/L, leading to a conclusion of 4 exceedances in 11 samples. Using the corrected units of ug/L, there are 0 exceedances in 11 samples. 0 of 24 samples exceeded the warm freshwater habitat water quality threshold for dissolved arsenic. 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 24 samples exceed the criterion 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 136484, Arsenic	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

253569

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 eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 11 samples exceeded the water quality threshold for Arsenic.

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 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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-08-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136484, Arsenic	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

253456

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 eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 11 samples exceeded the water quality threshold for Arsenic.

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-08-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136484, Arsenic	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

93886

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:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The dissolved arsenic criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater for dissolved arsenic is 0.150 mg/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) was collected at 1 monitoring site [ Conejo Creek Random Site 836 - 408BA0836]

Temporal Representation:

Data was collected on a single day 5/7/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 136484, Arsenic	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

257424

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	151608	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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

Regional Board Conclusion:	Benthic Community Effects are being considered for placement on the CWA section 303(d) List under sections 3.9 of the Listing Policy. Under section 3.9, additional lines of evidence (LOEs) associating the Benthic Community Effects decision with a water or sediment concentration of pollutants other than benthic-macroinvertebrate bioassessment or habitat assessment LOEs are necessary to place a water body on the 303(d) List for Benthic Community Effects. Three line(s) of evidence evaluating benthic-macroinvertebrate bioassessment data is/are available in the administrative record to assess this indicator. Three of three benthic-macroinvertebrate samples exceed the California Stream Condition Index (CSCI) impairment threshold. However, a minimum of two benthic-macroinvertebrate samples are needed to assess listing status. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing Benthic Community Effects in this waterbody segment on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Three of three benthic-macroinvertebrate bioassessment samples had CSCI scores below 0.79. The available information is insufficient to determine whether the waterbody/pollutant combination should be placed on the 303(d) List of impaired waters at this time. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. The CSCI is applicable statewide, accounts for a much wider range of natural variability, and provides equivalent scoring thresholds in all regions of the state. The CSCI will be used in the future for water quality assessment purposes statewide over the regional indices of biologic integrity (IBIs).

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:	The CSCI is applicable statewide, accounts for a much wider range of natural variability, and provides equivalent scoring thresholds in all regions of the state. The CSCI will be used in the future for water quality assessment purposes statewide over the regional indices of biologic integrity (IBIs).

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 151608, Benthic Community Effects	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

305413

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 408CAL007 to determine beneficial use support and the results are as follows: 1 of 1 samples exceeded the threshold. CSCI scores were from 0.668394308 to 0.668394308.

Data Reference:

California Stream Condition Index (CSCI) Scores for the 2024 Integrated Report for Region 4.

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce significant alterations in population or community ecology or receiving water biota. In addition, the health and life history characteristics of aquatic organisms in waters affected by controllable water quality factors shall not differ significantly from those for the same waters in areas unaffected by controllable water quality factors.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

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

Guideline Reference:

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

Spatial Representation:

Samples were collected from station 408CAL007.

Temporal Representation:

Samples were collected from 10/31/2001 to 10/31/2001.

Environmental Conditions:

QAPP Information:

Data were collected using Surface Water Ambient Monitoring Program protocols

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 151608, Benthic Community Effects	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

305397

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 408BA0836 to determine beneficial use support and the results are as follows: 1 of 1 samples exceeded the threshold. CSCI score is 0.546057012.

Data Reference:

California Stream Condition Index (CSCI) Scores for the 2024 Integrated Report for Region 4.

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

Samples were collected from station 408BA0836.

Temporal Representation:

Samples were collected 6/4/2014.

Environmental Conditions:

QAPP Information:

Data were collected using Surface Water Ambient Monitoring Program protocols

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 151608, Benthic Community Effects	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

95280

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

The CSCI score for this site is below the 0.79 threshold, and is therefore exceeding the water quality objective for the aquatic life beneficial use.

Data Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in, human, plant or animal, or aquatic life. Compliance with this objective will be determined by use of indicator organisms, analysis of species diversity, population density, growth anomalies, bioassays of appropriate duration or other appropriate methods as specified by the State or Regional Board. Region 4 Basin Plan.

Objective/Criterion Reference:

Evaluation Guideline:

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

Guideline Reference:

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

Spatial Representation:

The sample was collected at Conejo Creek Random Site 836.

Temporal Representation:

The sample was collected in May 2008.

Environmental Conditions:

QAPP Information:

Samples were collected for the SWAMP RWB4 Stormwater Monitoring Council CY 2008 following SWAMP protocols and stored in the SWAMP database.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	136485	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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 136485, Beryllium	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

253921

Pollutant:

Beryllium

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:

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: 767697 (RSW-001U).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136485, Beryllium	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

253622

Pollutant:

Beryllium

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:

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: 767698 (RSW-002D).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136534	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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

Regional Board Conclusion:	LOE 93887 has been replaced by LOE 309993 due to a reassessment of data using the U.S. EPA aquatic life benchmark. 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 136534, Bifenthrin	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

257679

Pollutant:

Bifenthrin

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 RWB4 So. CA Stormwater Monitoring Coalition data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Bifenthrin. 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:

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

SWAMP Data:

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 chronic criterion for bifenthrin is 0.1 ng/L (expressed as a 4-day average). If the freely dissolved concentrations of bifenthrin were reported or could be calculated then these values were used for this assessment. In the absence of freely dissolved concentrations, total concentrations were used.

Guideline Reference:

Water Quality Criteria Report for Bifenthrin

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

Data for this waterbody were collected over the date range 2014-06-04 to 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136534, Bifenthrin	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

309993

Pollutant:

Bifenthrin

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 RWB4 So. CA Stormwater Monitoring Coalition data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Bifenthrin. 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:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

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:

Evaluation Guideline:

Guideline Reference:

Water Quality Criteria Report for Bifenthrin

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

Data for this waterbody were collected over the date range 2008-05-07 to 2008-05-07

Environmental Conditions:

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	136486	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Boron
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 70 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 136486, Boron	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

243833

Pollutant:

Boron

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 data from the Camarillo Wastewater Reclamation Plant to determine beneficial use support. The results are as follows: 0 out of 38 samples exceed the criterion for Boron.

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 list a site specific objective for Boron in the Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) of 1 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Station RSW-001U (34.193825, -119.001478), located in Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list).

Temporal Representation:

The water samples were taken between 8/2/2017 - 10/7/2020, per the monitoring requirements listed in the Camarillo Wastewater Reclamation Plant NPDES Permit monitoring and reporting program.

Environmental Conditions:

QAPP Information:

The work was performed in accordance with the Camarillo Wastewater Reclamation Plant NDPES Permit quality assurance provisions for water quality monitoring.

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136486, Boron	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

243848

Pollutant:

Boron

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 data from the Camarillo Wastewater Reclamation Plant to determine beneficial use support. The results are as follows: 0 out of 32 samples exceed the criterion for Boron.

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:

Station RSW-002D (34.192402, -119.003827), located in Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list).

Temporal Representation:

The water samples were taken between 8/2/2017 - 10/7/2020, per the monitoring requirements listed in the Camarillo Wastewater Reclamation Plant NPDES Permit monitoring and reporting program.

Environmental Conditions:

QAPP Information:

The work was performed in accordance with the Camarillo Wastewater Reclamation Plant NDPES Permit quality assurance provisions for water quality monitoring.

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136487	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 136487, Cadmium	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

258014

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136487, Cadmium	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

253707

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 eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 3 samples exceeded the water quality threshold for Cadmium.

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2019-02-06 and 2020-08-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136487, Cadmium	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

253706

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 eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Cadmium.

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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-08-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136487, Cadmium	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

93889

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:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

California Toxics Rule (CTR) lists criterion continuous concentrations 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.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) was collected at 1 monitoring site [ Conejo Creek Random Site 836 - 408BA0836]

Temporal Representation:

Data was collected on a single day 5/7/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	136490	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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 136490, Chlorine	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

253646

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_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Chlorine, Total Residual.

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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2018-10-03 and 2019-12-04

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136490, Chlorine	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

253643

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_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Chlorine, Total Residual.

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2018-10-03 and 2019-12-04

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136541	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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

Regional Board Conclusion:	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 136541, Chlorpyrifos, methyl	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

258823

Pollutant:

Chlorpyrifos, methyl

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

SWAMP Data:

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 chlorpyrifos methyl is the USEPA Aquatic Life Benchmark of 0.085 ug/L for an invertebrate (acute).

Guideline Reference:

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):


DECISION ID	136546	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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:	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 136546, Chromium	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254029

Pollutant:

Chromium

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_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 6 samples exceeded the water quality threshold for Chromium.

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-08-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136546, Chromium	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

258773

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136546, Chromium	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

253635

Pollutant:

Chromium

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_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 6 samples exceeded the water quality threshold for Chromium.

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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-08-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136546, Chromium	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

93891

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:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) was collected at 1 monitoring site [ Conejo Creek Random Site 836 - 408BA0836]

Temporal Representation:

Data was collected on a single day 5/7/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	136492	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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:	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 136492, Chromium, hexavalent	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254034

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:

Water Board staff assessed eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 6 samples exceeded the water quality threshold for Chromium VI.

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-02-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136492, Chromium, hexavalent	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

253989

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:

Water Board staff assessed eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Chromium VI.

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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2018-02-07 and 2020-02-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136493	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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 136493, Chromium, trivalent	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254100

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:

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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2020-08-05 and 2020-08-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136493, Chromium, trivalent	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254172

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2020-08-05 and 2020-08-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136494	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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

Regional Board Conclusion:	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 68 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 136494, Copper	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

93893

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:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) was collected at 1 monitoring site [ Conejo Creek Random Site 836 - 408BA0836]

Temporal Representation:

Data was collected on a single day 5/7/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 136494, Copper	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

258873

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:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The dissolved copper 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 9 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136494, Copper	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254018

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 eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 33 samples exceeded the water quality threshold for Copper.

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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-08-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136494, Copper	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254268

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 eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 33 samples exceeded the water quality threshold for Copper.

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-08-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136495	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Cyanide
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. 2 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. 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 California Toxics Rule criterion for cyanide in water and this does not exceed the allowable frequency listed in Table 3.1 for warm freshwater habitat. 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 136495, Cyanide	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254139

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:

Water Board staff assessed eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 13 samples exceeded the water quality threshold for Cyanide.

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2017-10-04 and 2020-03-04

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136495, Cyanide	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254252

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:

Water Board staff assessed eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 19 samples exceeded the water quality threshold for Cyanide.

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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2017-10-04 and 2020-08-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136543	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 136543, Cyfluthrin	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

259286

Pollutant:

Cyfluthrin

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 RWB4 So. CA Stormwater Monitoring Coalition data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Cyfluthrin. 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:

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

SWAMP Data:

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 chronic criterion for cyfluthrin is 0.2 ng/L (expressed as a 4-day average). If the freely dissolved concentrations of cyfluthrin were reported or could be calculated then these values were used for this assessment. In the absence of freely dissolved concentrations, total concentrations were used.

Guideline Reference:

Water Quality Criteria Report for Cyfluthrin

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

Data for this waterbody were collected over the date range 2014-06-04 to 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	136545	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Cyhalothrin, Lambda
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:	LOE 93816 has been replaced by LOE 310696 due to a reassessment of data using the U.S. EPA aquatic life benchmark. 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 136545, Cyhalothrin, Lambda	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

262697

Pollutant:

Cyhalothrin, Lambda

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 RWB4 So. CA Stormwater Monitoring Coalition data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Lambda-cyhalothrin. 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:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The chronic criterion for lambda-cyhalothrin is 0.3 ng/L (expressed as a 4-day average). If the freely dissolved concentrations of lambda-cyhalothrin were reported or could be calculated then these values were used for this assessment. In the absence of freely dissolved concentrations, total concentrations were used.

Guideline Reference:

Water Quality Criteria Report for Lambda-cyhalothrin

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

Data for this waterbody were collected over the date range 2014-06-04 to 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136545, Cyhalothrin, Lambda	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

310696

Pollutant:

Cyhalothrin, Lambda

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 RWB4 So. CA Stormwater Monitoring Coalition data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Lambda-cyhalothrin. 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:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Water Quality Criteria Report for Lambda-cyhalothrin

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

Data for this waterbody were collected over the date range 2008-05-07 to 2008-05-07

Environmental Conditions:

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	136535	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Cypermethrin
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:	LOE 93818 has been replaced by LOE 310013 due to a reassessment of data using the U.S. EPA aquatic life benchmark. 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 136535, Cypermethrin	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

259680

Pollutant:

Cypermethrin

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 RWB4 So. CA Stormwater Monitoring Coalition data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Cypermethrin. 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:

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

SWAMP Data:

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 chronic criterion for cypermethrin is 0.3 ng/L (expressed as a 4-day average). If the freely dissolved concentrations of cypermethrin were reported or could be calculated then these values were used for this assessment. In the absence of freely dissolved concentrations, total concentrations were used.

Guideline Reference:

Water Quality Criteria Report for Cypermethrin

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

Data for this waterbody were collected over the date range 2014-06-04 to 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136535, Cypermethrin	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

310013

Pollutant:

Cypermethrin

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 RWB4 So. CA Stormwater Monitoring Coalition data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Cypermethrin. 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:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

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:

Evaluation Guideline:

Guideline Reference:

Water Quality Criteria Report for Cypermethrin

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

Data for this waterbody were collected over the date range 2008-05-07 to 2008-05-07

Environmental Conditions:

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	151758	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 151758, Dacthal	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

307331

Pollutant:

Dacthal

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

SWAMP Data:

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:

According to the USEPA Office of Pesticide Programs Ecotoxicity database, the aquatic life LC50 for Dacthal is 6600 ug/L.

Guideline Reference:

OPP Pesticide Ecotoxicity Database.

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	136544	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Deltamethrin
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:	LOE 93819 has been replaced by LOE 310422 due to a reassessment of data using the U.S. EPA aquatic life benchmark. 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 136544, Deltamethrin	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

260023

Pollutant:

Deltamethrin

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 RWB4 So. CA Stormwater Monitoring Coalition data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Deltamethrin. 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:

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

SWAMP Data:

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 deltamethrin is the USEPA Aquatic Life Benchmark of 0.000026 ug/L for an invertebrate (chronic).

Guideline Reference:

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

Data for this waterbody were collected over the date range 2014-06-04 to 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 136544, Deltamethrin	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

310422

Pollutant:

Deltamethrin

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:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

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:

Evaluation Guideline:

The evaluation guideline for deltamethrin is the USEPA Aquatic Life Benchmark of 0.000026 ug/L for an invertebrate (chronic).

Guideline Reference:

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2008-05-07 and 2008-05-07

Environmental Conditions:

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):


DECISION ID	136500	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Dyfonate (Fonofos or Fonophos)
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 136500, Dyfonate (Fonofos or Fonophos)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

262003

Pollutant:

Dyfonate (Fonofos or Fonophos)

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

SWAMP Data:

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 fonofos is the maximum acceptable toxicant concentration (MATC) of 0.45 ug/L. The MATC is calculated as the geometric mean of the lowest observed effect concentration (LOEC) of 0.64 ug/L and the no observed effect concentration (NOEC) of 0.31 ug/L, as determined in a 21 day toxicity study with the water flea, Daphnia magna. Threshold values (LOEC and NOEC) are from USEPA Office of Pesticide Programs Ecotoxicity database.

Guideline Reference:

OPP Pesticide Ecotoxicity Database.

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	136501	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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 136501, Endosulfan sulfate	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

260957

Pollutant:

Endosulfan sulfate

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136501, Endosulfan sulfate	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254494

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: 767698 (RSW-002D).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136501, Endosulfan sulfate	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254556

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: 767697 (RSW-001U).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136502	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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 136502, Endrin	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254872

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: 767698 (RSW-002D).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136502, Endrin	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

261140

Pollutant:

Endrin

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136502, Endrin	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254359

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: 767697 (RSW-001U).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136548	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Esfenvalerate/Fenvalerate
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:	LOE 93820 has been replaced by LOE 310216 due to a reassessment of data using the U.S. EPA aquatic life benchmark. 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 136548, Esfenvalerate/Fenvalerate	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

261314

Pollutant:

Esfenvalerate/Fenvalerate

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 RWB4 So. CA Stormwater Monitoring Coalition data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Esfenvalerate. 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:

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

SWAMP Data:

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 chronic criterion for esfenvalerate is 0.3 ng/L (expressed as a 4-day average). If the freely dissolved concentrations of esfenvalerate were reported or could be calculated then these values were used for this assessment. In the absence of freely dissolved concentrations, total concentrations were used.

Guideline Reference:

Water Quality Criteria Report for Esfenvalerate

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

Data for this waterbody were collected over the date range 2014-06-04 to 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136548, Esfenvalerate/Fenvalerate	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

310216

Pollutant:

Esfenvalerate/Fenvalerate

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:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

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:

Evaluation Guideline:

Guideline Reference:

Water Quality Criteria Report for Esfenvalerate

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2008-05-07 and 2008-05-07

Environmental Conditions:

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	136533	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 136533, Ethion	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

261347

Pollutant:

Ethion

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 RWB4 So. CA Stormwater Monitoring Coalition data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Ethion. 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:

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

SWAMP Data:

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 ethion is the USEPA Aquatic Life Benchmark of 0.028 ug/L for invertebrates (acute).

Guideline Reference:

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

Data for this waterbody were collected over the date range 2014-06-04 to 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):


DECISION ID	136537	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 136537, Ethoprop	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

261537

Pollutant:

Ethoprop

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

SWAMP Data:

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 ethoprop is the USEPA Aquatic Life Benchmark of 0.8 ug/L for an invertebrate (chronic).

Guideline Reference:

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):


DECISION ID	136540	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 136540, Fenitrothion	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

261402

Pollutant:

Fenitrothion

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

SWAMP Data:

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 fenitrothion is the USEPA Aquatic Life Benchmark of 0.087 ug/L for an invertebrate (chronic).

Guideline Reference:

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):


DECISION ID	136547	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Fenpropathrin
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:	LOE 93825 has been replaced by LOE 310551 due to a reassessment of data using the U.S. EPA aquatic life benchmark. 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 136547, Fenpropathrin	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

261592

Pollutant:

Fenpropathrin

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 RWB4 So. CA Stormwater Monitoring Coalition data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Fenpropathrin. 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:

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

SWAMP Data:

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 Fenpropathrin is the USEPA Aquatic Life Benchmark of 0.0015 ug/L for an invertebrate (chronic).

Guideline Reference:

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

Data for this waterbody were collected over the date range 2014-06-04 to 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 136547, Fenpropathrin	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

310551

Pollutant:

Fenpropathrin

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 RWB4 So. CA Stormwater Monitoring Coalition data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Fenpropathrin. 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:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

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:

Evaluation Guideline:

The evaluation guideline for Fenpropathrin is the USEPA Aquatic Life Benchmark of 0.0015 ug/L for an invertebrate (chronic).

Guideline Reference:

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

Data for this waterbody were collected over the date range 2008-05-07 to 2008-05-07

Environmental Conditions:

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):


DECISION ID	136503	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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 136503, Heptachlor	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254711

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:

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: 767697 (RSW-001U).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136503, Heptachlor	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

261918

Pollutant:

Heptachlor

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136503, Heptachlor	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255010

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:

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: 767698 (RSW-002D).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136504	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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 136504, Heptachlor epoxide	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

262527

Pollutant:

Heptachlor epoxide

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136504, Heptachlor epoxide	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254968

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:

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: 767697 (RSW-001U).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136504, Heptachlor epoxide	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254949

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:

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: 767698 (RSW-002D).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136506	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 136506, Lead	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

93834

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:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) was collected at 1 monitoring site [ Conejo Creek Random Site 836 - 408BA0836]

Temporal Representation:

Data was collected on a single day 5/7/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 136506, Lead	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254697

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 eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Lead.

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2019-02-06 and 2020-02-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136506, Lead	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255161

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 eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 6 samples exceeded the water quality threshold for Lead.

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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-08-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136506, Lead	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

262864

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	136508	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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 136508, Malathion	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

263131

Pollutant:

Malathion

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 RWB4 So. CA Stormwater Monitoring Coalition data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) 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:

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

Data for this waterbody were collected over the date range 2014-06-04 to 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	149490	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Mercury
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 149490, Mercury	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255145

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 eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Mercury.

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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2018-10-03 and 2019-12-04

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 149490, Mercury	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255349

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 eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Mercury.

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2018-10-03 and 2019-12-04

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136509	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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 136509, Methoxychlor	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255037

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: 767698 (RSW-002D).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136509, Methoxychlor	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255040

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: 767697 (RSW-001U).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136509, Methoxychlor	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

263580

Pollutant:

Methoxychlor

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	136510	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 136510, Methyl Parathion	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

264434

Pollutant:

Methyl Parathion

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 RWB4 So. CA Stormwater Monitoring Coalition data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Parathion, 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:

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

SWAMP Data:

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 California Department of Fish and Game instantaneous aquatic life criterion for methyl parathion is 0.08 ug/L.

Guideline Reference:

Hazard Assessment of the Insecticide Methyl Parathion to Aquatic Organisms in the Sacramento River System

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

Data for this waterbody were collected over the date range 2014-06-04 to 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	149491	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Microcystins
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 149491, Microcystins	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

263476

Pollutant:

Microcystins

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Wildlife Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

California Office of Environmental Health Hazard Assessment (OEHHA) established 2 ug/L of microcystins as the subchronic water concentration for dog intake/ingestion (Office of Environmental Health Hazard Assessment Public Health Action Level for microcystin and Human Recreational Uses (May 2012)). OEHHA Action Level for subchronic water intake, dog.

Guideline Reference:

Toxicological Summary and Suggested Action Levels to Reduce Potential Adverse Health Effects of Six Cyanotoxins

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 149491, Microcystins	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

263472

Pollutant:

Microcystins

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:

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The California Cyanobacteria and Harmful Algal Bloom (CCHAB) Network established 6 ug/L of microcystins as the water concentration protective of swimmers and other contact recreational users including water-skiing/jet-skiing, fishing, boating, sail boarding, and canoeing.

Guideline Reference:

Appendix to the CCHAB preliminary changes to the statewide voluntary guidance on cyanoHABs in recreational waters, January 2016. Appendix A. Description of cyanotoxin triggers in recreational waters.

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	136511	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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 136511, Mirex	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

263478

Pollutant:

Mirex

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 RWB4 So. CA Stormwater Monitoring Coalition data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) 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:

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

Data for this waterbody were collected over the date range 2014-06-04 to 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	136512	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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 136512, Naphthalene	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255044

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:

Ambient Water Quality Criteria for Naphthalene

Spatial Representation:

The samples were collected at 1 monitoring site: 767697 (RSW-001U).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136512, Naphthalene	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255045

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:

Ambient Water Quality Criteria for Naphthalene

Spatial Representation:

The samples were collected at 1 monitoring site: 767698 (RSW-002D).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136513	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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 are necessary to assess listing status. 1 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 in not 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 70 sample 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 136513, Nickel	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255260

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 eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 34 samples exceeded the water quality threshold for Nickel.

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 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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-08-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136513, Nickel	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255221

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 eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 34 samples exceeded the water quality threshold for Nickel.

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-08-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136513, Nickel	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

263797

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136513, Nickel	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

93946

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:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) was collected at 1 monitoring site [ Conejo Creek Random Site 836 - 408BA0836]

Temporal Representation:

Data was collected on a single day 5/7/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	149488	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	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. 4 of 66 and 0 of 1 samples exceeded the OBJECTIVE/GUIDELINE/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 149488, Nitrate	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

302286

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 149488, Nitrate	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

302613

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:

Water Board staff assessed eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 2 of 34 samples exceeded the water quality threshold for Nitrate as N.

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-06-03

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 149488, Nitrate	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

302601

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:

Water Board staff assessed eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 2 of 32 samples exceeded the water quality threshold for Nitrate as N.

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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-08-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136514	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 136514, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

243835

Pollutant:

Nitrate/Nitrite (Nitrite + Nitrate as N)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Groundwater Recharge

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed data from the Camarillo Wastewater Reclamation Plant to determine beneficial use support. The results are as follows: 0 out of 1 samples exceed the criterion for Nitrate + Nitrite as N.

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 list a site specific objective for Nitrate + Nitrite as N in the Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) of 10 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Station RSW-001U (34.193825, -119.001478), located in Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list).

Temporal Representation:

The water samples were taken on 1/8/2020, per the monitoring requirements listed in the Camarillo Wastewater Reclamation Plant NPDES Permit monitoring and reporting program.

Environmental Conditions:

QAPP Information:

The work was performed in accordance with the Camarillo Wastewater Reclamation Plant NDPES Permit quality assurance provisions for water quality monitoring.

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136514, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

93947

Pollutant:

Nitrate/Nitrite (Nitrite + Nitrate as N)

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:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Table 3-8 of The Water Quality Control Plan for the Los Angeles Region specifies the Nitrate/Nitrite as N objective for the Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) within the Calleguas-Conejo Creek watershed's Above Portrero Road reach boundary as 10 mg/L.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) was collected at 1 monitoring site [ Conejo Creek Random Site 836 - 408BA0836]

Temporal Representation:

Data was collected on a single day 5/7/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 136514, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

243844

Pollutant:

Nitrate/Nitrite (Nitrite + Nitrate as N)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Groundwater Recharge

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:

Station RSW-002D (34.192402, -119.003827), located in Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list).

Temporal Representation:

The water samples were taken on 6/3/2020, per the monitoring requirements listed in the Camarillo Wastewater Reclamation Plant NPDES Permit monitoring and reporting program.

Environmental Conditions:

QAPP Information:

The work was performed in accordance with the Camarillo Wastewater Reclamation Plant NDPES Permit quality assurance provisions for water quality monitoring.

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136514, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

244216

Pollutant:

Nitrate/Nitrite (Nitrite + Nitrate as N)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Groundwater Recharge

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ 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 lists a site specific objective for Nitrate/Nitrite (Nitrite + Nitrate as N) in Calleguas Creek Reach 9A of 10 mg/L

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Station 408BA0836 (34.1907194768, -119.005109779), located in Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list).

Temporal Representation:

Water samples were taken on 6/4/2014 for the Southern California Stormwater Monitoring Coalition.

Environmental Conditions:

QAPP Information:

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	136515	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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 136515, Organophosphate Pesticides	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

264326

Pollutant:

Organophosphate Pesticides

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136515, Organophosphate Pesticides	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255528

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:

Water Board staff assessed eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Organophosphorus Pesticides.

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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2019-08-07

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136515, Organophosphate Pesticides	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255552

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2018-05-02 and 2018-05-02

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136516	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 136516, Oxadiazon	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

264161

Pollutant:

Oxadiazon

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

SWAMP Data:

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 Oxadiazon is the USEPA Aquatic Life Benchmark of 0.88 ug/L for a fish (chronic).

Guideline Reference:

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):


DECISION ID	151861	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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. Five lines of evidence are available in the administrative record to assess this pollutant. All oxygen samples are in the dissolved fraction, so all lines of evidence for "Oxygen, dissolved" will be manually added. For lines of evidence 308001 and 308180, the data provider has indicated errors in data reporting, including that values of 0 represent days where no samples were collected. These values have been omitted and the data reassessed. LOE 308180: 6 of 32 samples exceeded the objective for dissolved oxygen. LOE 308001: 1 of 32 samples exceeded the objective for dissolved oxygen. LOE 93950: 0 of 1 samples exceeded the objective for dissolved oxygen. LOE 308213: 0 of 1 samples exceeded the objective for dissolved oxygen. LOE 2043: 6 of 111 samples exceeded the objective for Organic Enrichment/Low Dissolved Oxygen. 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. 7 of 65 samples and 6 of 111 samples exceeded the objectives 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 151861, Oxygen, Dissolved	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

308180

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:

Water Board staff assessed eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 6 of 32 samples exceeded the water quality threshold for Oxygen, Dissolved.

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-10-07

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 151861, Oxygen, Dissolved	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

308001

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:

Water Board staff assessed eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 1 of 32 samples exceeded the water quality threshold for Oxygen, Dissolved.

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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-10-07

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 151861, Oxygen, Dissolved	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

308213

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 151861, Oxygen, Dissolved	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

93950

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:

Data Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region (page 3-11) 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:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) was collected at 1 monitoring site [ Conejo Creek Random Site 836 - 408BA0836]

Temporal Representation:

Data was collected on a single day 5/7/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 151861, Oxygen, Dissolved	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2043

Pollutant:

Organic Enrichment/Low Dissolved Oxygen

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

111

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

One-hundred and eleven water samples, 6 samples exceeding (SWRCB, 2003).

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Basin Plan: The dissolved oxygen content of all surface waters designated as WARM shall not be depressed below 5 mg/L as a result of waste discharge.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Two sites.

Temporal Representation:

Summer, fall, winter, spring (1997-2000).

Environmental Conditions:

QAPP Information:

NPDES monitoring.

QAPP Information Reference(s):


DECISION ID	136518	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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 136518, Parathion	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

264597

Pollutant:

Parathion

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 RWB4 So. CA Stormwater Monitoring Coalition data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) 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:

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

Data for this waterbody were collected over the date range 2014-06-04 to 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	136519	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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 136519, Pentachlorophenol (PCP)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255519

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: 767698 (RSW-002D).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136519, Pentachlorophenol (PCP)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255518

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: 767697 (RSW-001U).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136549	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 136549, Permethrin	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

264735

Pollutant:

Permethrin

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 RWB4 So. CA Stormwater Monitoring Coalition data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Permethrin. 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:

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

SWAMP Data:

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 chronic criterion for permethrin is 1 ng/L (expressed as a 4-day average). If the freely dissolved concentrations of permethrin were reported or could be calculated then these values were used for this assessment. In the absence of freely dissolved concentrations, total concentrations were used.

Guideline Reference:

Water Quality Criteria Report for Permethrin

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

Data for this waterbody were collected over the date range 2014-06-04 to 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136549, Permethrin	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

310846

Pollutant:

Permethrin

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 RWB4 So. CA Stormwater Monitoring Coalition data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Permethrin. 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:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

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:

Evaluation Guideline:

Guideline Reference:

Water Quality Criteria Report for Permethrin

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

Data for this waterbody were collected over the date range 2008-05-07 to 2008-05-07

Environmental Conditions:

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	136532	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 136532, Pyrethroids	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

311020

Pollutant:

Pyrethroids

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 RWB4 So. CA Stormwater Monitoring Coalition data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Pyrethroids. 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:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

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:

Evaluation Guideline:

The summed ratios of the pyrethroid pesticides bifenthrin, cyfluthrin, cypermethrin, esfenvalerate, lambda-cyhalothrin, permethrin and their respective chronic concentration goals are not to exceed 1. If the freely dissolved concentrations of these pesticides were reported or could be calculated then these values were used for this assessment. In the absence of freely dissolved concentrations, total concentrations were used.

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

Data for this waterbody were collected over the date range 2008-05-07 to 2008-05-07

Environmental Conditions:

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 136532, Pyrethroids	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

310754

Pollutant:

Pyrethroids

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:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

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:

Evaluation Guideline:

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2008-05-07 and 2008-05-07

Environmental Conditions:

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 136532, Pyrethroids	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

265525

Pollutant:

Pyrethroids

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 RWB4 So. CA Stormwater Monitoring Coalition data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Pyrethroids. 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:

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

SWAMP Data:

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:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

Data for this waterbody were collected over the date range 2014-06-04 to 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	136522	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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:	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 136522, Selenium	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

266063

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136522, Selenium	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255652

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 eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 3 samples exceeded the water quality threshold for Selenium.

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-02-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136522, Selenium	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

266106

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136522, Selenium	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

93913

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:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The selenium criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.005 mg/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) was collected at 1 monitoring site [ Conejo Creek Random Site 836 - 408BA0836]

Temporal Representation:

Data was collected on a single day 5/7/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 136522, Selenium	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255694

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 eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Selenium.

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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-02-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136523	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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:	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 136523, Silver	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

266420

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:

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136523, Silver	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

93914

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:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) was collected at 1 monitoring site [ Conejo Creek Random Site 836 - 408BA0836]

Temporal Representation:

Data was collected on a single day 5/7/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 136523, Silver	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

256047

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: 767698 (RSW-002D).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136523, Silver	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255978

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: 767697 (RSW-001U).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136525	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Temperature, water
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. 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 66 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 136525, Temperature, water	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

256026

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 eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 32 samples exceeded the water quality threshold for Temperature.

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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-10-07

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136525, Temperature, water	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

256052

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 eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 32 samples exceeded the water quality threshold for Temperature.

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-10-07

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136525, Temperature, water	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

266979

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136525, Temperature, water	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

93923

Pollutant:

Temperature, water

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:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

For waters designated WARM, water temperature shall not be altered by more than 5 deg. F above the natural temperature. At no time shall these WARM-designated waters be raised above 80 deg. F as a result of waste discharges.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) was collected at 1 monitoring site [ Conejo Creek Random Site 836 - 408BA0836]

Temporal Representation:

Data was collected on a single day 5/7/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	136526	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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 136526, Thallium	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255903

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: 767697 (RSW-001U).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136526, Thallium	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255904

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: 767698 (RSW-002D).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136530	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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. 1 of 76 and 0 of 1 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 136530, Turbidity	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

256306

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:

Water Board staff assessed eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 38 samples exceeded the water quality threshold for Turbidity.

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-10-07

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136530, Turbidity	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

268127

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:

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136530, Turbidity	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

256084

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:

Water Board staff assessed eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 1 of 38 samples exceeded the water quality threshold for Turbidity.

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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-10-07

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	136531	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 136531, Zinc	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

93927

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:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) was collected at 1 monitoring site [ Conejo Creek Random Site 836 - 408BA0836]

Temporal Representation:

Data was collected on a single day 5/7/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 136531, Zinc	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

256255

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 eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 6 samples exceeded the water quality threshold for Zinc.

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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-08-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136531, Zinc	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

256209

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 eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 6 samples exceeded the water quality threshold for Zinc.

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-08-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136531, Zinc	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

268568

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:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	136497	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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 136497, alpha-Endosulfan (Endosulfan 1)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

260693

Pollutant:

alpha-Endosulfan (Endosulfan 1)

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	136517	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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 136517, beta-Endosulfan (Endosulfan 2)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

260813

Pollutant:

beta-Endosulfan (Endosulfan 2)

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	136520	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

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. Six lines of evidence are available in the administrative record to assess this pollutant. The data provider has indicated that lines of evidence 255457 and 255501 mistakenly report a value of 0 for days where no samples were collected. The data have been manually reassessed to remove these values. LOE 255457: 0 of 32 samples exceeded the warm freshwater habitat objective for pH. LOE 255501: 0 of 32 samples exceeded the warm freshwater habitat objective for pH. 0 of 2 samples exceeded the warm freshwater habitat objective for pH. 0 of 1 sample exceeded the water contact recreation objective for pH. 0 of 1 sample exceeded the non-contact recreation objective for pH. 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 66, 0 of 1 and 0 of 1 samples exceeded the objectives 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 136520, pH	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

93908

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Los Angeles Basin: the pH for insland 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:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) was collected at 1 monitoring site [ Conejo Creek Random Site 836 - 408BA0836]

Temporal Representation:

Data was collected on a single day 5/7/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 136520, pH	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

93907

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Non-Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Los Angeles Basin: the pH for insland 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:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) was collected at 1 monitoring site [ Conejo Creek Random Site 836 - 408BA0836]

Temporal Representation:

Data was collected on a single day 5/7/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 136520, pH	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255501

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 eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 32 samples exceeded the water quality threshold for pH.

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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-10-07

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136520, pH	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

265096

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

SWAMP Data:

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: 408BA0836 (Conejo Creek Random Site 836).

Temporal Representation:

The samples were collected between the dates of 2014-06-04 and 2014-06-04

Environmental Conditions:

QAPP Information:

SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136520, pH	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

255457

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 eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 32 samples exceeded the water quality threshold for pH.

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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-10-07

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136520, pH	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

93906

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:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Los Angeles Basin: the pH for insland 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:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) was collected at 1 monitoring site [ Conejo Creek Random Site 836 - 408BA0836]

Temporal Representation:

Data was collected on a single day 5/7/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	136505	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Iron
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:	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 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. 2 of 14 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 136505, Iron	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254886

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 eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Iron.

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 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: 767698 (RSW-002D).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-08-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136505, Iron	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

254906

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 eSMR_Camarillo WRP data for Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion) to determine beneficial use support and results are as follows: 2 of 7 samples exceeded the water quality threshold for Iron.

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: 767697 (RSW-001U).

Temporal Representation:

The samples were collected between the dates of 2017-08-02 and 2020-08-05

Environmental Conditions:

QAPP Information:

LARRY WALKER ASSOCIATES. 2008. Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP).

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136505, Iron	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

93826

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:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Central Valley Region, Tulare Lake Basin: waters shall not contain chemical constituents in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

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:

Data for this line of evidence for Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) was collected at 1 monitoring site [ Conejo Creek Random Site 836 - 408BA0836]

Temporal Representation:

Data was collected on a single day 5/7/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	136489	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Chloride
Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Sources:	Agriculture \| Atmospheric Deposition \| Groundwater Withdrawal \| See TMDL documentation
TMDL Name:	Calleguas Creek Boron/Sulfate/TDS (4)
TMDL Project Code:	357
Date TMDL Approved by USEPA:	12/02/2008
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 in favor of placing this water segment-pollutant combination on the CWA section 303(d) List. in the Being Addressed portion 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. 55 of 62 samples exceed the objective and this exceeds the allowable frequency listed in Table 3.2 of the Listing Policy. 4. The TMDL for Salts in the Calleguas Creek Watershed was approved by USEPA on 12/2/2008. 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 136489, Chloride	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

243849

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:

Water Board staff assessed data from the Camarillo Wastewater Reclamation Plant to determine beneficial use support. The results are as follows: 28 out of 31 samples exceed the criterion for Chloride.

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 list a site specific objective for Chloride in the Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) of 150 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Station RSW-002D (34.192402, -119.003827), located in Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list).

Temporal Representation:

The water samples were taken between 8/2/2017 - 9/2/2020, per the monitoring requirements listed in the Camarillo Wastewater Reclamation Plant NPDES Permit monitoring and reporting program.

Environmental Conditions:

QAPP Information:

The work was performed in accordance with the Camarillo Wastewater Reclamation Plant NDPES Permit quality assurance provisions for water quality monitoring.

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)

Line of Evidence (LOE) for Decision ID 136489, Chloride	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

244215

Pollutant:

Chloride

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 data from the Southern California Stormwater Monitoring Coalition to determine beneficial use support. The results are as follows: one out of one samples exceed the criterion for chloride.

Data Reference:

Field, Habitat, Toxicity, 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 lists a site specific objective for Chloride in Calleguas Creek Reach 9A of 150 of mg/L

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Station 408BA0836 (34.1907194768, -119.005109779), located in Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list).

Temporal Representation:

Water samples were taken on 6/4/2014 for the Southern California Stormwater Monitoring Coalition.

Environmental Conditions:

QAPP Information:

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 136489, Chloride	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

243834

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:

Water Board staff assessed data from the Camarillo Wastewater Reclamation Plant to determine beneficial use support. The results are as follows: 27 out of 31 samples exceed the criterion for Chloride.

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:

Station RSW-001U (34.193825, -119.001478), located in Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list).

Temporal Representation:

The water samples were taken between 8/2/2017 - 9/2/2020, per the monitoring requirements listed in the Camarillo Wastewater Reclamation Plant NPDES Permit monitoring and reporting program.

Environmental Conditions:

QAPP Information:

The work was performed in accordance with the Camarillo Wastewater Reclamation Plant NDPES Permit quality assurance provisions for water quality monitoring.

QAPP Information Reference(s):

Calleguas Creek Watershed Management Plan Quality Assurance Project Plan (QAPP)


DECISION ID	69331	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Excess Algal Growth
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)(2016)
Revision Status	Original
Reason for Delisting:	Flaws in original listing
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This water quality condition is being considered for delisting under section 4 of the Listing Policy. Under this section of the Policy, a minimum of one line of evidence is needed to assess listing status. The Calleguas Creek Nitrogen TMDL was adopted by RWQCB in October 2002 and was subsequently approved by USEPA in June 2003. This TMDL will address this water body condition. Qualitative information on excess algal growth alone is not sufficient to support continued placement on the section 303(d) list (Listing Policy section 3.7). Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of removing this water segment-pollutant combination from the Water Quality Limited Segments portion of the section 303(d) list.

Regional Board Decision Recommendation:	This is a decision previously approved by the State Water Resources Control Board and the USEPA. No new data were assessed by the Regional Board for the current. 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 69331, Excess Algal Growth	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2039

Pollutant:

Excess Algal Growth

LOE Subgroup:

Pollutant-Nuisance

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

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

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Temporal Representation:

Environmental Conditions:

QAPP Information:

QA Info Missing

QAPP Information Reference(s):


DECISION ID	68263	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Indicator Bacteria
Final Listing Decision:	Do Not Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not Delist from 303(d) list (TMDL required list)(2016)
Revision Status	Original
Sources:	A Source Unknown
Expected TMDL Completion Date:	2027
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	303(d) listing decisions made prior to 2006 were not held in an assessment database and are not available in the administrative record. Even though fecal coliform is no longer the applicable indicator bacteria for fresh waters in the Los Angeles Region, studies show (Noble et al., 2003) that 80 to 90% of fecal coliform are E coli in the Los Angeles Region, and therefore the fecal coliform data used to list this waterbody is a reasonable stand in for E coli until E coli data is available. This conservative approach will limit the potential for delisting this waterbody which data has shown to be impaired for fecal indicating bacteria.

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

State Board Review of Regional Board Conclusion and Recommendation:

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 68263, Indicator Bacteria	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2046

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Twelve bacteria samples, 5 samples exceeding 400/100 ml standard. Geomean of 206 exceeds 200/100 ml standard (SWRCB, 2003).

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Basin Plan: In waters designated for water contact recreation (REC-1), the fecal coliform concentration shall not exceed a log mean of 200/100 ml (based on a minimum of not less than four samples for any 30-day period), nor shall more than 10 percent of total samples during any 30-day period exceed 400/100 ml.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One site (small reach).

Temporal Representation:

Summer, fall, winter, spring.

Environmental Conditions:

QAPP Information:

Calleguas Creek Characterization Study

QAPP Information Reference(s):


DECISION ID	68335	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Nitrogen, Nitrate
Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)(2016)
Revision Status	Original
Sources:	Nonpoint Source \| Point Source
TMDL Name:	Calleguas Creek Nitrogen (1)
TMDL Project Code:	228
Date TMDL Approved by USEPA:	06/20/2003
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 4.1 of the Listing Policy. Under section 4.1 a single line of evidence are necessary to assess listing status. 1 line of evidence is available in the administrative record to assess this pollutant. 0 of the 0 samples exceeded the CRITERIA. Based on the readily available data and information, the weight of evidence indicates that there is insufficient 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. 0 of 0 samples exceeded the CRITERIA and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 28 samples is needed to determine if a beneficial use is fully supported using table 4.1. 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 not be removed from the section 303(d) list because applicable water quality standards for the pollutant are being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

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 68335, Nitrogen, Nitrate	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2041

Pollutant:

Nitrogen, Nitrate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

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

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Temporal Representation:

Environmental Conditions:

QAPP Information:

QA Info Missing

QAPP Information Reference(s):


DECISION ID	77819	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Manganese
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 are necessary to assess listing status. 1 line of evidence is available in the administrative record to assess this pollutant. 0 of 1 sample exceeded the CRITERIA. Based on the readily available data and information, the weight of evidence indicates that there is insufficient 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. 0 of 1 sample exceeded the CRITERIA and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to SECTION 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 77819, Manganese	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

96170

Pollutant:

Manganese

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:

Data Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

No individual chemical or combination of chemicals shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

The Manganese criteria for the protection of human health from the fish consumption component of water contact recreation (REC-1) use is 100 ug/L (California Toxics Rule, 2000).

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:

Data for this line of evidence for Calleguas Creek Reach 9A (was lower part of Conejo Creek Reach 1 on 1998 303d list) was collected at 1 monitoring site [ Conejo Creek Random Site 836 - 408BA0836]

Temporal Representation:

Data was collected on a single day 5/7/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	76968	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Trash
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (TMDL required list)(2016)
Revision Status	Original
Sources:	A Source Unknown
Expected TMDL Completion Date:	2021
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the section 303(d) list under section 3.7 of the Listing Policy. Under section 3.7 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 for 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. Seven of 11 samples exceeded the narrative objectives for trash listed in the Basin Plan, and evaluated using numeric targets derived in Los Angeles River Trash TMDL 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 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. 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 76968, Trash	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

30190

Pollutant:

Trash

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Wildlife Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Seven of 11 samples exceeded the numeric target of zero trash.

Data Reference:

Calleguas Creek Watershed Monitoring Report prepared by Wishtoyo Foundation, Ventura Coastkeeper, 2006

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

From the Los Angeles RWQCB Basin Plan: Waters shall not contain floating materials, including solids, liquids, foams, and scum, in concentrations that cause nuisance or adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Narrative objective evaluated using numeric target of zero trash in Los Angeles River Trash TMDL and other regional trash TMDLs.

Guideline Reference:

Spatial Representation:

One monitoring station in Conejo Creek, Reach 9A (CJ1).

Temporal Representation:

11 observations and trash counts were taken every month from February to December of 2006.

Environmental Conditions:

QAPP Information:

Data was collected in compliance with the sampling and monitoring procedures detailed in Wishtoyo Foundation Volunteer Monitoring Quality Assurance Project Plan.

QAPP Information Reference(s):

Wishtoyo Foundation Volunteer Monitoring Quality Assurance Project Plan


DECISION ID	69426	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	ChemA (tissue)
Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)(2016)
Revision Status	Original
Sources:	Agriculture-storm runoff
TMDL Name:	Calleguas Creek Historic Pesticides (5)
TMDL Project Code:	358
Date TMDL Approved by USEPA:	03/24/2006
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal on the section 303(d) list under sections 2.2 of the Listing Policy. Under 2.2 of the Policy, a minimum of one line of evidence is needed to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the section 303(d) list. There is sufficient justification to place it in the Being Addressed portion of the 303(d) list because a TMDL has been completed and adopted by the Los Angeles RWQCB and approved by USEPA, and is expected to result in attainment of the standard.

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. 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 69426, ChemA (tissue)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

30129

Pollutant:

ChemA (tissue)

LOE Subgroup:

Narrative Description Data

Matrix:

Not Specified

Fraction:

None

Beneficial Use:

Commercial or recreational collection of fish, shellfish, or organisms

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

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 69426, ChemA (tissue)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2058

Pollutant:

ChemA (tissue)

LOE Subgroup:

Pollutant-Tissue

Matrix:

Tissue

Fraction:

Not Recorded

Beneficial Use:

Commercial or recreational collection of fish, shellfish, or organisms

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

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

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Temporal Representation:

Environmental Conditions:

QAPP Information:

QA Info Missing

QAPP Information Reference(s):


DECISION ID	68540	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Chlordane (tissue)
Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)(2016)
Revision Status	Original
Sources:	Nonpoint Source
TMDL Name:	Calleguas Creek Historic Pesticides (5)
TMDL Project Code:	358
Date TMDL Approved by USEPA:	03/14/2006
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for delisting under sections 4.1 of the Listing Policy. Under section 4.1 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. The Calleguas Creek Historic Pesticides TMDL was approved by RWQCB in 2005 and subsequently approved by USEPA. Based on the readily available information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination in the Water Quality Limited Segments Being Addressed portion of the section 303(d) list. This 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. Two out of 2 samples exceeded the Screening Value. However, a TMDL is in place to address this pollutant in this water body. 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:	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. 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 68540, Chlordane (tissue)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2052

Pollutant:

Chlordane

LOE Subgroup:

Pollutant-Tissue

Matrix:

Tissue

Fraction:

Total

Beneficial Use:

Commercial or recreational collection of fish, shellfish, or organisms

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fish tissue analysis

Data Used to Assess Water Quality:

Two tissue samples, 2 samples exceeding (TSMP, 2002).

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Los Angeles RWQCB Basin Plan: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

OEHHA Screening Value: 30 ug/kg (Brodberg and Pollock, 1999). Section 6.1.3 of the Listing Policy does not allow the use of MTRLs to evaluate fish and shellfish tissue data.

Guideline Reference:

Spatial Representation:

Sample was collected spatially.

Temporal Representation:

One-time sample.

Environmental Conditions:

QAPP Information:

TSMP

QAPP Information Reference(s):


DECISION ID	70411	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	DDT (tissue)
Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)(2016)
Revision Status	Original
Sources:	Nonpoint Source
TMDL Name:	Calleguas Creek Historic Pesticides (5)
TMDL Project Code:	358
Date TMDL Approved by USEPA:	01/01/2005
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for delisting under sections 4.1 of the Listing Policy. Under section 4.1 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. The Calleguas Creek Historic Pesticides TMDL was approved by RWQCB in 2005 and subsequently approved by USEPA. Based on the readily available information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination in the Water Quality Limited Segments Being Addressed portion of the section 303(d) list. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Four out of 4 samples exceeded the Screening Value. However, a TMDL is in place to address this pollutant in this water body. 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:	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. 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 70411, DDT (tissue)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2055

Pollutant:

DDT (Dichlorodiphenyltrichloroethane)

LOE Subgroup:

Pollutant-Tissue

Matrix:

Tissue

Fraction:

Total

Beneficial Use:

Commercial or recreational collection of fish, shellfish, or organisms

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fish tissue analysis

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Los Angeles RWQCB Basin Plan: Toxic pollutants shall not be present at levels that will bioaccumulate in aquatic life to levels which are harmful to aquatic life or human health.

Objective/Criterion Reference:

Evaluation Guideline:

1000 ng/g - NAS Guideline (whole fish).

Guideline Reference:

Spatial Representation:

One station located at Rancho Road crossing south west of Camarillo.

Temporal Representation:

Samples were collected in 6/2/92 and 6/25/98.

Environmental Conditions:

QAPP Information:

Toxic Substances Monitoring Program 1992-93 Data Report.

Environmental Chemistry Quality Assurance and Data Report for the Toxic Substances Monitoring Program,1996-2000. Department of Fish and Game

QAPP Information Reference(s):


DECISION ID	69580	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Dieldrin (tissue)
Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)(2016)
Revision Status	Original
Sources:	Nonpoint Source
TMDL Name:	Calleguas Creek Historic Pesticides (5)
TMDL Project Code:	358
Date TMDL Approved by USEPA:	03/14/2006
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for delisting under sections 4.1 of the Listing Policy. Under section 4.1 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. The Calleguas Creek Historic Pesticides TMDL was approved by RWQCB in 2005 and subsequently approved by USEPA. Based on the readily available information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination in the Water Quality Limited Segments Being Addressed portion of the section 303(d) list. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Four out of 4 samples exceeded the Screening Value. However, a TMDL is in place to address this pollutant in this water body. 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:	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. 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 69580, Dieldrin (tissue)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2048

Pollutant:

Dieldrin

LOE Subgroup:

Pollutant-Tissue

Matrix:

Tissue

Fraction:

Total

Beneficial Use:

Commercial or recreational collection of fish, shellfish, or organisms

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fish tissue analysis

Data Used to Assess Water Quality:

Two tissue samples, 2 samples exceeding (TSMP, 2002).

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Los Angeles RWQCB Basin Plan: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

OEHHA Screening Value: 2.0 ug/kg (Brodberg and Pollock, 1999). Section 6.1.3 of the Listing Policy does not allow the use of MTRLs to evaluate fish and shellfish tissue data.

Guideline Reference:

Spatial Representation:

Sample was collected spatially.

Temporal Representation:

One-time sample.

Environmental Conditions:

QAPP Information:

TSMP QAPP.

QAPP Information Reference(s):


DECISION ID	99305	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Endosulfan (tissue)
Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)(2016)
Revision Status	Original
Sources:	Agriculture-storm runoff
TMDL Name:	Calleguas Creek Historic Pesticides (5)
TMDL Project Code:	358
Date TMDL Approved by USEPA:	03/24/2006
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal on the section 303(d) list under sections 2.2 of the Listing Policy. Under 2.2 of the Policy, a minimum of one line of evidence is needed to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the section 303(d) list. There is sufficient justification to place it in the Being Addressed portion of the 303(d) list because a TMDL has been completed and adopted by the Los Angeles RWQCB and approved by USEPA, and is expected to result in attainment of the standard.

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. 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 99305, Endosulfan (tissue)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2059

Pollutant:

Endosulfan

LOE Subgroup:

Pollutant-Water

Matrix:

Not Specified

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

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

Data Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Temporal Representation:

Environmental Conditions:

QAPP Information:

QA Info Missing

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 99305, Endosulfan (tissue)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

30130

Pollutant:

Endosulfan (tissue)

LOE Subgroup:

Narrative Description Data

Matrix:

Not Specified

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

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:

Temporal Representation:

Environmental Conditions:

QAPP Information:

QA information unavailable.

QAPP Information Reference(s):


DECISION ID	99306	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Lindane/gamma-Hexachlorocyclohexane (gamma-HCH) (tissue)
Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)(2016)
Revision Status	Original
Sources:	Agriculture-storm runoff
TMDL Name:	Calleguas Creek Historic Pesticides (5)
TMDL Project Code:	358
Date TMDL Approved by USEPA:	03/24/2006
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal on the section 303(d) list under sections 2.2 of the Listing Policy. Under 2.2 of the Policy, a minimum of one line of evidence is needed to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the section 303(d) list. There is sufficient justification to place it in the Being Addressed portion of the 303(d) list because a TMDL has been completed and adopted by the Los Angeles RWQCB and approved by USEPA, and is expected to result in attainment of the standard.

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. 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 99306, Lindane/gamma-Hexachlorocyclohexane (gamma-HCH) (tissue)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2053

Pollutant:

Lindane/gamma Hexachlorocyclohexane (gamma-HCH)

LOE Subgroup:

Pollutant-Tissue

Matrix:

Tissue

Fraction:

Total

Beneficial Use:

Commercial or recreational collection of fish, shellfish, or organisms

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fish tissue analysis

Data Used to Assess Water Quality:

Two tissue samples with no samples exceeding the screening value (TSMP, 2002).

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Los Angeles RWQCB Basin Plan: Toxic pollutants shall not be present at levels that will bioaccumulate in aquatic life to levels which are harmful to aquatic life or human health.

Objective/Criterion Reference:

Evaluation Guideline:

OEHHA Screening Value: 30 ug/kg for Lindane (gamma-HCH) (Brodberg and Pollock, 1999). Section 6.1.3 of the Listing Policy does not allow the use of MTRLs to evaluate fish and shellfish tissue data.

Guideline Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Spatial Representation:

Sample was collected spatially.

Temporal Representation:

One-time sample.

Environmental Conditions:

QAPP Information:

TSMP

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 99306, Lindane/gamma-Hexachlorocyclohexane (gamma-HCH) (tissue)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

30131

Pollutant:

Lindane/gamma-Hexachlorocyclohexane (gamma-HCH) (tissue)

LOE Subgroup:

Narrative Description Data

Matrix:

Not Specified

Fraction:

None

Beneficial Use:

Commercial or recreational collection of fish, shellfish, or organisms

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

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:

Temporal Representation:

Environmental Conditions:

QAPP Information:

QA information unavailable.

QAPP Information Reference(s):


DECISION ID	74886	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Nitrate as Nitrate (NO3)
Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)(2016)
Revision Status	Original
Sources:	Nonpoint Source \| Point Source
TMDL Name:	Calleguas Creek Nitrogen (1)
TMDL Project Code:	228
Date TMDL Approved by USEPA:	06/20/2003
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal from the section 303(d) list under section 4.1 of the Listing Policy. Under section 4.1 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. The Calleguas Creek Nitrogen TMDL was adopted by RWQCB in October 2002 and was subsequently approved by USEPA in June 20, 2003. 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 in the Water Quality Limited Segments Being Addressed portion of the section 303(d) list. This conclusion is based on the staff findings that: 1. It is unknown whether the data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Six of 12 samples exceeded the nitrate as nitrate (NO3) water quality objective. A TMDL has been developed and approved by USEPA and an approved implementation plan is expected to result in attainment of the standard. At least 28 samples are needed before a pollutant can be considered for removal from the list using the frequencies presented 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:	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. 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 74886, Nitrate as Nitrate (NO3)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2045

Pollutant:

Nitrate as Nitrate (NO3)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Groundwater Recharge

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Twelve water samples, 6 samples exceeding (SWRCB, 2002).

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Basin Plan: Waters shall not exceed 10 mg/L nitrogen as nitrate-nitrogen plus nitrite-nitrogen (NO2-N), 45 mg/L as nitrate (NO3), 10 mg/L as nitrate-nitrogen (NO3-N) or as otherwise designated in [another part of the Basin Plan].

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One site only (Conejo Creek).

Temporal Representation:

Summer, fall, winter, spring.

Environmental Conditions:

Data 3-4 years old, data measured at site, during all seasons.

QAPP Information:

Calleguas Creek Characterization Study

QAPP Information Reference(s):


DECISION ID	69865	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Nitrogen, Nitrite
Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)(2016)
Revision Status	Original
Sources:	A Source Unknown
TMDL Name:	Calleguas Creek Nitrogen (1)
TMDL Project Code:	228
Date TMDL Approved by USEPA:	06/20/2003
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. 18 of the 110 samples exceed the OBJECTIVE. 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. 18 of 110 samples exceed the OBJECTIVE 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 69865, Nitrogen, Nitrite	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2044

Pollutant:

Nitrogen, Nitrite

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Groundwater Recharge

Number of Samples:

110

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Out of one-hundred and ten water samples, 18 samples exceeded the water quality objective (SWRCB, 2003).

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One site only (Conejo Creek).

Temporal Representation:

Summer, fall, winter, spring.

Environmental Conditions:

QAPP Information:

NPDES report.

QAPP Information Reference(s):


DECISION ID	68236	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	PCBs (Polychlorinated biphenyls) (tissue)
Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)(2016)
Revision Status	Original
Sources:	Nonpoint Source
TMDL Name:	Calleguas Creek PCBs (7)
TMDL Project Code:	360
Date TMDL Approved by USEPA:	01/01/2005
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal from the section 303(d) list under section 4.1 of the Listing Policy. Under section 4.1 a single line of evidence is necessary to assess listing status. Two samples exceed the USEPA screening value, however, a TMDL is in place to address this pollutant in this water body. Based on the readily available information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination in the Water Quality Limited Segments Being Addressed portion of the section 303(d) list. This 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. Two of 2 samples exceeded the USEPA Screening value and a TMDL is in place to address this pollutant in this water body. 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:	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. 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 68236, PCBs (Polychlorinated biphenyls) (tissue)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2050

Pollutant:

PCBs (Polychlorinated biphenyls)

LOE Subgroup:

Pollutant-Tissue

Matrix:

Tissue

Fraction:

Total

Beneficial Use:

Commercial or recreational collection of fish, shellfish, or organisms

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fish tissue analysis

Data Used to Assess Water Quality:

Two composite tissue samples, 2 samples exceeding (TSMP, 2002).

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Los Angeles RWQCB Basin Plan: Toxic pollutants shall not be present at levels that will bioaccumulate in aquatic life to levels which are harmful to aquatic life or human health.

Objective/Criterion Reference:

Evaluation Guideline:

OEHHA Screening Value: 20 ug/kg (Brodberg and Pollock, 1999). Section 6.1.3 of the Listing Policy does not allow the use of MTRLs to evaluate fish and shellfish tissue data.

Guideline Reference:

Spatial Representation:

Samples were collected spatially.

Temporal Representation:

One-time sample.

Environmental Conditions:

QAPP Information:

TSMP

QAPP Information Reference(s):


DECISION ID	73773	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

Pollutant:	Toxaphene (tissue & sediment)
Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)(2016)
Revision Status	Original
Sources:	Nonpoint Source
TMDL Name:	Calleguas Creek Historic Pesticides (5)
TMDL Project Code:	358
Date TMDL Approved by USEPA:	01/01/2005
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for delisting under sections 4.1 of the Listing Policy. Under section 4.1 a single line of evidence is necessary to assess listing status. Based on the readily available information, the weight of evidence indicates that there is sufficient justification in favor of keeping this water segment-pollutant combination in the Water Quality Limited Segments Being Addressed portion of the 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. Four out of 4 samples exceeded the Screening Value. However, a TMDL is in place to address this pollutant in this water body. 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:	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. 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 73773, Toxaphene (tissue & sediment)	Region 4
Calleguas Creek Reach 9A (Conejo Creek: Calleguas Creek Reach 3 to Camrosa Diversion)

LOE ID:

2057

Pollutant:

Toxaphene

LOE Subgroup:

Pollutant-Tissue

Matrix:

Tissue

Fraction:

Total

Beneficial Use:

Commercial or recreational collection of fish, shellfish, or organisms

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fish tissue analysis

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Los Angeles RWQCB Basin Plan: Toxic pollutants shall not be present at levels that will bioaccumulate in aquatic life to levels which are harmful to aquatic life or human health.

Objective/Criterion Reference:

Evaluation Guideline:

100 ng/g - NAS Guideline (Whole fish).

Guideline Reference: