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

Supporting Information

Regional Board 5 - Central Valley Region

Water Body Name:	San Luis Canal (Merced County)
Water Body ID:	CAR5412000020190906033387
Water Body Type:	River & Stream


DECISION ID	160241	Region 5
San Luis Canal (Merced County)

Pollutant:	Boron
Final Listing Decision:	Do Not Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Sources:	A Source Unknown
TMDL Priority:	Low
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal from the CWA section 303(d) List under section 4.1 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. Four lines of evidence are available in the administrative record to assess pollutant. One hundred of the 218 samples exceed the threshold for Agricultural Supply. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One hundred of the 218 samples exceed the threshold for Agricultural Supply and this exceeds the allowable frequency listed in Table 4.1 of the Listing Policy. 4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 160241, Boron	Region 5
San Luis Canal (Merced County)

LOE ID:

186606

Pollutant:

Boron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Agricultural Supply

Number of Samples:

142

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Grasslands Bypass Project data for San Luis Canal (Merced County) to determine beneficial use support and results are as follows: 74 of 142 samples exceeded the water quality threshold for Boron.

Data Reference:

Field, Habitat, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Waters shall not contain chemical constituents in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)

Evaluation Guideline:

Water Quality for Agriculture, published by the Food and Agriculture Organization of the United Nations in 1985, contains criteria protective of various agricultural uses of water, including irrigation of various types of crops and stock watering. At or below the limits presented in the Water Quality Goals tables, agricultural uses of water should not be limited. These criteria were used to translate narrative water quality objectives for chemical constituents that prohibit chemicals in concentrations that would impair agricultural uses of water. The criteria for boron is 700 ug/L (0.7 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 (541MER563)

Temporal Representation:

The samples were collected between the dates of 2010-09-13 and 2013-09-23

Environmental Conditions:

QAPP Information:

U.S. Bureau of Reclamation. 2006. Quality Assurance Project Plan for the Compliance Monitoring Program for the Operation of the Grasslands Bypass Project., U.S. Bureau of Reclamation. 2015. Quality Assurance Project Plan for the Compliance Monitoring Program for the Operation of the Grassland Bypass Project.

QAPP Information Reference(s):

Quality Assurance Project Plan for the Compliance Monitoring Program for the Operation of the Grasslands Bypass Project

QAPP Information Reference(s):

Quality Assurance Project Plan for the Compliance Monitoring Program for the Operation of the Grassland Bypass Project

Line of Evidence (LOE) for Decision ID 160241, Boron	Region 5
San Luis Canal (Merced County)

LOE ID:

186589

Pollutant:

Boron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Agricultural Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Westside San Joaquin River Watershed Coalition data for San Luis Canal (Merced County) to determine beneficial use support and results are as follows: 9 of 22 samples exceeded the water quality threshold for Boron.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Waters shall not contain chemical constituents in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site (541MER563)

Temporal Representation:

The samples were collected between the dates of 2016-02-09 and 2018-02-13

Environmental Conditions:

QAPP Information:

Pacific EcoRisk. 2013. QAPP for Westside San Joaquin River Watershed Coalition.

QAPP Information Reference(s):

QAPP for Westside San Joaquin River Watershed Coalition

Line of Evidence (LOE) for Decision ID 160241, Boron	Region 5
San Luis Canal (Merced County)

LOE ID:

330851

Pollutant:

Boron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Agricultural Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Westside San Joaquin River Watershed Coalition data for San Luis Canal (Merced County) to determine beneficial use support and results are as follows: 17 of 53 samples exceeded the water quality threshold for Boron.

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Waters shall not contain chemical constituents in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

Water Quality for Agriculture, published by the Food and Agriculture Organization of the United Nations in 1985, contains criteria protective of various agricultural uses of water, including irrigation of various types of crops and stock watering. These criteria were used to translate narrative water quality objectives for chemical constituents that prohibit chemicals in concentrations that would impair agricultural uses of water. The guideline for boron is 700 ug/L (0.7 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: 541SLC152 (San Luis Canal at Hwy 152 (Site L3)).

Temporal Representation:

The samples were collected between the dates of 2017-06-13 and 2022-01-11

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

QAPP Reference for Irrigated Lands Regulatory Program

Line of Evidence (LOE) for Decision ID 160241, Boron	Region 5
San Luis Canal (Merced County)

LOE ID:

330859

Pollutant:

Boron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Agricultural Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Grasslands Bypass Project data for San Luis Canal (Merced County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Boron.

Data Reference:

Field, Habitat, Toxicity, WQ from the Grasslands Bypass Project for the 2026 Integrated Report in Region 5

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Waters shall not contain chemical constituents in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

Water Quality for Agriculture, published by the Food and Agriculture Organization of the United Nations in 1985, contains criteria protective of various agricultural uses of water, including irrigation of various types of crops and stock watering. These criteria were used to translate narrative water quality objectives for chemical constituents that prohibit chemicals in concentrations that would impair agricultural uses of water. The guideline for boron is 700 ug/L (0.7 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: 541MER563 (San Luis Canal Upstream of Splits).

Temporal Representation:

The samples were collected between the dates of 2010-08-30 and 2010-08-30

Environmental Conditions:

QAPP Information:

GBP QAPP - Grasslands Bypass Project

QAPP Information Reference(s):

SWRCB - Region5 - GBP QAPP - Grasslands Bypass Project - 402652


DECISION ID	160242	Region 5
San Luis Canal (Merced County)

Pollutant:	Oxygen, Dissolved
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. One of the 60 samples exceed the objective for aquatic life. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One of the 60 samples exceed the objective for aquatic life and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 160242, Oxygen, Dissolved	Region 5
San Luis Canal (Merced County)

LOE ID:

332084

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:

Water Board staff assessed Westside San Joaquin River Watershed Coalition data for San Luis Canal (Merced County) to determine beneficial use support and results are as follows: 1 of 44 samples exceeded the water quality threshold for Oxygen, Dissolved.

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The minimum dissolved oxygen concentration for waters designated as WARM is 5.0 mg/L. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin Basin)

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 541SLC152 (San Luis Canal at Hwy 152 (Site L3)).

Temporal Representation:

The samples were collected between the dates of 2017-06-13 and 2022-01-11

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

QAPP Reference for Irrigated Lands Regulatory Program

Line of Evidence (LOE) for Decision ID 160242, Oxygen, Dissolved	Region 5
San Luis Canal (Merced County)

LOE ID:

208324

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Westside San Joaquin River Watershed Coalition data for San Luis Canal (Merced County) to determine beneficial use support and results are as follows: 0 of 16 samples exceeded the water quality threshold for Oxygen, Dissolved.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The minimum dissolved oxygen concentration for waters designated as WARM is 5.0 mg/L. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin Basin)

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (541MER563)

Temporal Representation:

The samples were collected between the dates of 2016-02-09 and 2017-08-08

Environmental Conditions:

QAPP Information:

Pacific EcoRisk. 2013. QAPP for Westside San Joaquin River Watershed Coalition.

QAPP Information Reference(s):

QAPP for Westside San Joaquin River Watershed Coalition


DECISION ID	164118	Region 5
San Luis Canal (Merced County)

Pollutant:	Selenium
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Sources:	A Source Unknown
TMDL Priority:	Low
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Six lines of evidence are available in the administrative record to assess this pollutant. Eight of the 52 samples exceed the 0.002 mg/L monthly average objective for WARM. Zero of the 53 samples exceed the 0.02 mg/L seven-day average objective for WARM. Zero of the 181 samples exceed the 0.005 mg/L 4-day average objective for WARM. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Eight of the 52 samples exceed the 0.002 mg/L monthly average objective for WARM and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 164118, Selenium	Region 5
San Luis Canal (Merced County)

LOE ID:

193504

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Westside San Joaquin River Watershed Coalition data for San Luis Canal (Merced County) to determine beneficial use support and results are as follows: 0 of 22 samples exceeded the water quality threshold for Selenium.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The selenium criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 5 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

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 (541MER563)

Temporal Representation:

The samples were collected between the dates of 2016-02-09 and 2018-02-13

Environmental Conditions:

QAPP Information:

Pacific EcoRisk. 2013. QAPP for Westside San Joaquin River Watershed Coalition.

QAPP Information Reference(s):

QAPP for Westside San Joaquin River Watershed Coalition

Line of Evidence (LOE) for Decision ID 164118, Selenium	Region 5
San Luis Canal (Merced County)

LOE ID:

344290

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Waterboard staff assessed Westside San Joaquin River Watershed Coalition data for San Luis Canal (Merced County) to determine beneficial use support and results are as follows: 0 of 52 samples exceeded the water quality standard for Selenium

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for selenium in this water body is 0.02 mg/L (as a 7-day average).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (541SLC152)

Temporal Representation:

The samples were collected between the dates of 2017-06-13 and 2022-01-11.

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

QAPP Reference for Irrigated Lands Regulatory Program

Line of Evidence (LOE) for Decision ID 164118, Selenium	Region 5
San Luis Canal (Merced County)

LOE ID:

344289

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Waterboard staff assessed Grasslands Bypass Project data for San Luis Canal (Merced County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality standard for Selenium

Data Reference:

Field, Habitat, Toxicity, WQ from the Grasslands Bypass Project for the 2026 Integrated Report in Region 5

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for selenium in this water body is 0.02 mg/L (as a 7-day average).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (541MER563)

Temporal Representation:

The samples were collected between the dates of 2010-08-30 and 2010-08-30.

Environmental Conditions:

QAPP Information:

GBP QAPP - Grasslands Bypass Project

QAPP Information Reference(s):

SWRCB - Region5 - GBP QAPP - Grasslands Bypass Project - 402652

Line of Evidence (LOE) for Decision ID 164118, Selenium	Region 5
San Luis Canal (Merced County)

LOE ID:

344274

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Grasslands Bypass Project for the 2026 Integrated Report in Region 5

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for selenium in this water body is 0.002 mg/L (as a monthly average).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (541MER563)

Temporal Representation:

The samples were collected between the dates of 2010-08-30 and 2010-08-30.

Environmental Conditions:

QAPP Information:

GBP QAPP - Grasslands Bypass Project

QAPP Information Reference(s):

SWRCB - Region5 - GBP QAPP - Grasslands Bypass Project - 402652

Line of Evidence (LOE) for Decision ID 164118, Selenium	Region 5
San Luis Canal (Merced County)

LOE ID:

344275

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Waterboard staff assessed Westside San Joaquin River Watershed Coalition data for San Luis Canal (Merced County) to determine beneficial use support and results are as follows: 8 of 51 samples exceeded the water quality standard for Selenium

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for selenium in this water body is 0.002 mg/L (as a monthly average).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (541SLC152)

Temporal Representation:

The samples were collected between the dates of 2017-06-13 and 2022-01-11.

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

QAPP Reference for Irrigated Lands Regulatory Program

Line of Evidence (LOE) for Decision ID 164118, Selenium	Region 5
San Luis Canal (Merced County)

LOE ID:

193549

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

159

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Grasslands Bypass Project data for San Luis Canal (Merced County) to determine beneficial use support and results are as follows: 0 of 159 samples exceeded the water quality threshold for Selenium.

Data Reference:

Field, Habitat, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The selenium criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 5 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (541MER563)

Temporal Representation:

The samples were collected between the dates of 2010-09-07 and 2013-09-23

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Quality Assurance Project Plan for the Compliance Monitoring Program for the Operation of the Grasslands Bypass Project

QAPP Information Reference(s):

Quality Assurance Project Plan for the Compliance Monitoring Program for the Operation of the Grassland Bypass Project


DECISION ID	160243	Region 5
San Luis Canal (Merced County)

Pollutant:	pH
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Sources:	A Source Unknown
TMDL Priority:	Low
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Eight of the 45 samples exceed the objective for WARM. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Eight of the 45 samples exceed the objective for WARM and this exceeds the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 160243, pH	Region 5
San Luis Canal (Merced County)

LOE ID:

332476

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Westside San Joaquin River Watershed Coalition data for San Luis Canal (Merced County) to determine beneficial use support and results are as follows: 8 of 45 samples exceeded the water quality threshold for pH.

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: pH should not be lower than 6.5 or higher than 8.5.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 541SLC152 (San Luis Canal at Hwy 152 (Site L3)).

Temporal Representation:

The samples were collected between the dates of 2017-06-13 and 2021-05-11

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

QAPP Reference for Irrigated Lands Regulatory Program