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

Supporting Information

Regional Board 7 - Colorado River Basin Region

Water Body Name:	Lateral Unnamed Drain 2 tributary
Water Body ID:	CAR7231000020230818050416
Water Body Type:	River & Stream


DECISION ID	161235	Region 7
Lateral Unnamed Drain 2 tributary

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 161235, Aluminum	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

334510

Pollutant:

Aluminum

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RWB7 Monitoring data for Lateral Unnamed Drain 2 tributary to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Aluminum.

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level incorporated by reference in the Water Quality Control Plan, Colorado River Basin Region for Aluminum is 1 mg/L (Title 22 of the California Code of Regulations).

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 161235, Aluminum	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

334485

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, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

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:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

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: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	169438	Region 7
Lateral Unnamed Drain 2 tributary

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

Regional Board Conclusion:	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 169438, Ammonia	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

334536

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

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 listed in the Aquatic Life Ambient Water Quality Criteria for AmmoniaNAFreshwater 2013 document.

Objective/Criterion Reference:

Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 169438, Ammonia	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

334552

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Basin Plan: No individual chemical or combination of chemicals shall be present in concentrations that adversely affect beneficial uses (Water Quality Control Plan, Colorado River Basin).

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

EPA's Lifetime Health advisory level for total ammonia is 30.0 mg/L as stated on page 8 of the 2006 edition of the drinking water standards and health advisories. This Advisory Level is defined as 'the concentration of a chemical in drinking water that is not expected to cause any adverse noncarcinogenic effects for up to ten days of exposure.'

Guideline Reference:

2018 Edition of the Drinking Water Standards and Health Advisories

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	161217	Region 7
Lateral Unnamed Drain 2 tributary

Pollutant:	Arsenic
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 161217, Arsenic	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

334602

Pollutant:

Arsenic

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

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 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:

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: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 161217, Arsenic	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

333492

Pollutant:

Arsenic

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RWB7 Monitoring data for Lateral Unnamed Drain 2 tributary to determine beneficial use support and the results are as follows: 1 of the 1 samples exceeded the evaluation guideline for Arsenic .

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

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. There shall be no increase in hazardous chemical concentrations found in bottom sediments or aquatic life. (Water Quality Control Plan, Colorado River Basin)

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

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

Guideline Reference:

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

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

Data for this waterbody were collected over the date range 2019-04-09 to 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 161217, Arsenic	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

334597

Pollutant:

Arsenic

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RWB7 Monitoring data for Lateral Unnamed Drain 2 tributary to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Arsenic.

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for arsenic is 0.01 mg/L (Title 22 of the California Code of Regulations).

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	161236	Region 7
Lateral Unnamed Drain 2 tributary

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 161236, Bromide	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

334665

Pollutant:

Bromide

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

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:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

National Academy of Science Health Advisory water quality objective for Bromide is 2300 ug/L.

Guideline Reference:

National Academy of Sciences, Drinking Water and Health, Volume 3 (1980)

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	161218	Region 7
Lateral Unnamed Drain 2 tributary

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 161218, Cadmium	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

333531

Pollutant:

Cadmium

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RWB7 Monitoring data for Lateral Unnamed Drain 2 tributary to determine beneficial use support and the results are as follows: 0 of the 1 samples exceeded the evaluation guideline for Cadmium .

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

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

Guideline Reference:

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

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

Data for this waterbody were collected over the date range 2019-04-09 to 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 161218, Cadmium	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

334685

Pollutant:

Cadmium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

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: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 161218, Cadmium	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

334711

Pollutant:

Cadmium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Maximum Contaminant Level for cadmium in the Basin Plan is 0.005 mg/L (Water Quality Control Plan, Colorado River Basin).

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	161219	Region 7
Lateral Unnamed Drain 2 tributary

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 161219, Chloride	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

334744

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

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:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

The Drinking Water Secondary Maximum Contaminant Levels (SMCLs) for consumer acceptance were used: 500 mg/l Chloride (CCR, title 22).

Guideline Reference:

California Code of Regulations, Title 22, Division 4, Chapter 15. Domestic Water Quality and Monitoring

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 161219, Chloride	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

334734

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:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	161234	Region 7
Lateral Unnamed Drain 2 tributary

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 161234, Chromium	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

334798

Pollutant:

Chromium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for total chromium is 0.05 mg/L (Title 22 of the California Code of Regulations).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 161234, Chromium	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

334802

Pollutant:

Chromium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

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 180 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 161234, Chromium	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

333543

Pollutant:

Chromium

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

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

Guideline Reference:

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

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

Data for this waterbody were collected over the date range 2019-04-09 to 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	161220	Region 7
Lateral Unnamed Drain 2 tributary

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 161220, Copper	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

334877

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, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

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: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 161220, Copper	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

333575

Pollutant:

Copper

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

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

Guideline Reference:

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

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

Data for this waterbody were collected over the date range 2019-04-09 to 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 161220, Copper	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

334861

Pollutant:

Copper

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

No individual chemical or combination of chemicals shall be present in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Colorado River Basin).

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

The California Secondary MCL for copper is 1.0 mg/L (Title 22 California Code of Regulations).

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	161221	Region 7
Lateral Unnamed Drain 2 tributary

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 161221, Fluoride	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

335249

Pollutant:

Fluoride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

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:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

The California Primary Maximum Contaminant Level (MCL) for Fluoride, is 2 mg/l.

Guideline Reference:

Water Quality for Agriculture, Food and Agriculture Organization of the United Nations - Irrigation and Drainage Paper No. 29, Rev 1, Rome (1985)

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	161222	Region 7
Lateral Unnamed Drain 2 tributary

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 161222, Lead	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

335454

Pollutant:

Lead

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

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: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 161222, Lead	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

335443

Pollutant:

Lead

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Maximum Contaminant Level for lead in the Basin Plan is 0.015 mg/L (Water Quality Control Plan, Colorado River Basin).

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 161222, Lead	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

333643

Pollutant:

Lead

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

The evaluation guideline for lead is the probable effect concentration (PEC) of 128 mg/kg dry weight (MacDonald et al., 2000a).

Guideline Reference:

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

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

Data for this waterbody were collected over the date range 2019-04-09 to 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	161223	Region 7
Lateral Unnamed Drain 2 tributary

Pollutant:	Manganese
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 161223, Manganese	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

335504

Pollutant:

Manganese

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

No individual chemical or combination of chemicals shall be present in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Colorado River Basin).

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

The California Secondary MCL for manganese is 0.5 mg/L (Title 22 California Code of Regulations).

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	161224	Region 7
Lateral Unnamed Drain 2 tributary

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 161224, Nickel	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

335621

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

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: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 161224, Nickel	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

333693

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

The evaluation guideline for nickel is the probable effect concentration (PEC) of 48.6 mg/kg dry weight (MacDonald et al., 2000a).

Guideline Reference:

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

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

Data for this waterbody were collected over the date range 2019-04-09 to 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 161224, Nickel	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

335622

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for nickel is 0.1 mg/L (Title 22 of the California Code of Regulations).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	169542	Region 7
Lateral Unnamed Drain 2 tributary

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

Regional Board Conclusion:	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 169542, Nitrogen, Nitrate	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

335648

Pollutant:

Nitrogen, Nitrate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for Nitrate as N is 10000 ug/L (Title 22 of the California Code of Regulations).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	169555	Region 7
Lateral Unnamed Drain 2 tributary

Pollutant:	Nitrogen, Nitrite
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 169555, Nitrogen, Nitrite	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

335671

Pollutant:

Nitrogen, Nitrite

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for nitrite (as N) is 1.0 mg/L (Title 22 of the California Code of Regulations).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	161225	Region 7
Lateral Unnamed Drain 2 tributary

Pollutant:	Oxygen, Dissolved
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 161225, Oxygen, Dissolved	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

335717

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Colorado River Basin, WARM Water Habitat Objective, Chapter III, states the following: The dissolved oxygen concentration for warm water habitats shall not be reduced below 5.0 mg/l at any time.

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	161227	Region 7
Lateral Unnamed Drain 2 tributary

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

Regional Board Conclusion:	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 161227, Selenium	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

336205

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

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: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 161227, Selenium	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

336211

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Maximum Contaminant Level for selenium in the Basin Plan is 0.05 mg/L (Water Quality Control Plan, Colorado River Basin).

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	161228	Region 7
Lateral Unnamed Drain 2 tributary

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 161228, Silver	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

336255

Pollutant:

Silver

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

No individual chemical or combination of chemicals shall be present in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Colorado River Basin).

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

The California Secondary MCL for silver is 0.1 mg/L (Title 22 California Code of Regulations).

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 161228, Silver	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

336249

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, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

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: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	169587	Region 7
Lateral Unnamed Drain 2 tributary

Pollutant:	Specific Conductivity
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 169587, Specific Conductivity	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

336276

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

No individual chemical or combination of chemicals shall be present in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Colorado River Basin).

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

The California Secondary MCL for specific conductance is 900 uS/cm (Title 22 California Code of Regulations).

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	161229	Region 7
Lateral Unnamed Drain 2 tributary

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 161229, Sulfates	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

336325

Pollutant:

Sulfates

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Basin Plan: No individual chemical or combination of chemicals shall be present in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

The Drinking Water Secondary Maximum Contaminant Levels (SMCLs) for consumer acceptance of 500 mg/l.

Guideline Reference:

California Code of Regulations, Title 22, Division 4, Chapter 15. Domestic Water Quality and Monitoring

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	161230	Region 7
Lateral Unnamed Drain 2 tributary

Pollutant:	Total Dissolved Solids
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 161230, Total Dissolved Solids	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

336369

Pollutant:

Total Dissolved Solids

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

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:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

California Secondary Maximum Contaminant Levels (MCLs) for consumer acceptance objective for total dissolved solids is 1000 mg/L.

Guideline Reference:

California Code of Regulations, Title 22, Division 4, Chapter 15. Domestic Water Quality and Monitoring

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	161231	Region 7
Lateral Unnamed Drain 2 tributary

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 161231, Toxicity	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

353911

Pollutant:

Toxicity

LOE Subgroup:

Toxicity

Matrix:

Sediment

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:

0 of the 1 samples collected by SWAMP RWB7 Monitoring for Lateral Unnamed Drain 2 tributary exhibited toxicity. A sample may have multiple toxicity test results, but will only be counted once. A sample is defined as being collected on the same day and the same location. The following organisms and parameters were utilized for the toxicity tests: Hyalella azteca for Growth (wt/surv indiv), Hyalella azteca for Survival.

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

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: 723STUD02 ( Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd ).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09.

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	161232	Region 7
Lateral Unnamed Drain 2 tributary

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 161232, Turbidity	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

336392

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

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:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

California Maximum Contaminant Levels (MCLs) apply to ambient surface waters under the Basin Plan's 'Chemical Constituents' objective. The Secondary MCL for turbidity is 5 NTU. Calculation of a numeric objective for other beneficial uses requires comparison with upstream or other background data which may not be available as part of the data used for water quality assessment.

Guideline Reference:

California Code of Regulations, Title 22, Division 4, Chapter 15. Domestic Water Quality and Monitoring

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	161233	Region 7
Lateral Unnamed Drain 2 tributary

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 161233, Zinc	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

333752

Pollutant:

Zinc

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

The evaluation guideline for zinc is the probable effect concentration (PEC) of 459 mg/kg dry weight (MacDonald et al., 2000a).

Guideline Reference:

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

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

Data for this waterbody were collected over the date range 2019-04-09 to 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	161226	Region 7
Lateral Unnamed Drain 2 tributary

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 161226, pH	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

335864

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Colorado River Basin Region's water quality objective for all surface waters states the following: Since the regional waters are somewhat alkaline, pH shall range from 6.0-9.0. Discharges shall not cause any changes in pH detrimental to beneficial water uses.

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 161226, pH	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

335825

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:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 161226, pH	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

335933

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:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 161226, pH	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

336048

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Freshwater Replenishment

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 161226, pH	Region 7
Lateral Unnamed Drain 2 tributary

LOE ID:

336050

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 7

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Colorado River Basin Region (Includes amendments effective on or before March 30, 2019)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 723STUD02 (Lateral Unknown Drain 2 Tributary 0.5mileswestofLackRd).

Temporal Representation:

The samples were collected between the dates of 2019-04-09 and 2019-04-09

Environmental Conditions:

QAPP Information:

General SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP