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

Supporting Information

Regional Board 2 - San Francisco Bay Region

Water Body Name: Frenchmans Creek (San Mateo)
Water Body ID: CAR2022100020210423068232
Water Body Type: River & Stream
 
DECISION ID
148781
Region 2     
Frenchmans Creek (San Mateo)
 
Pollutant: Indicator Bacteria
Final Listing Decision: List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Sources: See TMDL documentation
TMDL Name: Pillar Point and Venice Beach Bacteria TMDL & Bacteria Objectives Cleanup
TMDL Project Code: 1285
Date TMDL Approved by USEPA: 02/08/2022
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 3.11 of the Listing Policy. Under this section when all other listing factors do not result in the listing of a water segment but information indicates non-attainment of standards, a water segment shall be evaluated to determine whether the weight of evidence demonstrates that water quality standard is not attained. If the weight of evidence indicates non-attainment, the water segment shall be placed on the CWA section 303(d) List. When making a listing decision based on the situation-specific weight of evidence, the Regional Water Board must justify its recommendation by:

• Providing any data or information including current conditions supporting the decision;
• Describing in fact sheets how the data or information affords a substantial basis in fact from which the decision can be reasonably inferred;
• Demonstrating that the weight of evidence of the data and information indicate that the water quality standard is not attained; and
• Demonstrating that the approach used is scientifically defensible and reproducible.

Frenchmans Creek drains directly to Venice Beach. Venice Beach is impaired by indicator bacteria (pathogens) and subject to the Pillar Point Harbor and Venice Beach Bacteria TMDL. The weight of evidence indicates that there is sufficient justification for placing this water segment-pollutant combination on the CWA section 303(d) List, specifically on the being addressed portion of the CWA section 303(d) List because a TMDL has been completed and approved by RWQCB and USEPA, and is expected to result in attainment of the standard. This conclusion is based on the staff findings that:

1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. Frenchmans Creek drains directly to Venice Beach which is impaired by pathogens. Enterococcus measured at the beach for more than a decade show consistent exceedances of the REC-1 water quality objectives and the sources in Frenchmans Creek watershed contribute to bacterial contamination at the beach.

2. The Pillar Point Harbor and Venice Beach Bacteria TMDL focuses on improving water quality at the beaches, but the TMDL covers the entire area draining to the coast between the Harbor and Venice Beach, and specifically addresses sources of bacteria in Frenchmans Creek including horse boarding facilities, onsite wastewater treatment systems, sanitary sewer system failures and municipal runoff. These sources have been identified in the TMDL and the implementation plan requires actions to address them. In particular, the Waste Discharge Requirements Order for Confined Animal Facilities requires the boarding facilities to better manage animal waste and the load allocation for septic systems are regulated under the Local Agency Management Program.

3. Periodic sampling of E.coli at the lower segment of Frenchmans Creek (2020-21), showed frequent exceedances of the statistical threshold value of 320 cfu/100 mL. Human and horse markers were detected during microbial source tracking evaluation. Therefore, based on the readily available data and information, the weight of evidence indicates that there is sufficient justification for placing this water segment-pollutant combination on the being addressed portion of the CWA section 303(d) List because a TMDL has been completed and approved by RWQCB and USEPA, and is expected to result in attainment of the standard.

4. This process is scientifically defensible and reproducible. The Frenchmans Creek watershed was part of the Pillar Point Harbor and Venice Beach Bacteria TMDL assessment. The TMDL assessment included a rigorous technical review, the public participation process, and approval by U.S. EPA.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of 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 148781, Indicator Bacteria
Region 2     
Frenchmans Creek (San Mateo)
 
LOE ID: 300333
 
Pollutant: Escherichia coli (E. coli)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: STV
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 3
Number of Exceedances: 1
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP RWB2 Monitoring data for Frenchmans Creek (San Mateo) to determine beneficial use support and the results are as follows: 1 of the 3 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.
Data Reference: Field, Habitat, Tissue, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: The bacteria water quality objective to protect the REC-1 beneficial use where the salinity is less than 1 parts per thousand 95 percent or more of the time applies a statistical threshold value to E. coli of 320 cfu/100 mL, not to be exceeded by more than 10 percent of samples within a calendar month (ISWEBE 2018).
Objective/Criterion Reference: Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site(s), station(s): 202FRE050 (Frenchmans Creek directly d/s of Hwy 1).
Temporal Representation: The samples were collected between the days of 2019-11-21 and 2020-06-23 .
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 148781, Indicator Bacteria
Region 2     
Frenchmans Creek (San Mateo)
 
LOE ID: 300491
 
Pollutant: Escherichia coli (E. coli)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: STV
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP RWB2 Monitoring data for Frenchmans Creek (San Mateo) to determine beneficial use support and the results are as follows: 0 of the 2 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.
Data Reference: Field, Habitat, Tissue, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: The bacteria water quality objective to protect the REC-1 beneficial use where the salinity is less than 1 parts per thousand 95 percent or more of the time applies a statistical threshold value to E. coli of 320 cfu/100 mL, not to be exceeded by more than 10 percent of samples within a calendar month (ISWEBE 2018).
Objective/Criterion Reference: Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site(s), station(s): 202FRE500 (Frenchmans Creek across from Ananda Valley Farm).
Temporal Representation: The samples were collected between the days of 2020-03-16 and 2020-06-23 .
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 148781, Indicator Bacteria
Region 2     
Frenchmans Creek (San Mateo)
 
LOE ID: 300394
 
Pollutant: Escherichia coli (E. coli)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: STV
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 3
Number of Exceedances: 1
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP RWB2 Monitoring data for Frenchmans Creek (San Mateo) to determine beneficial use support and the results are as follows: 1 of the 3 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.
Data Reference: Field, Habitat, Tissue, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: The bacteria water quality objective to protect the REC-1 beneficial use where the salinity is less than 1 parts per thousand 95 percent or more of the time applies a statistical threshold value to E. coli of 320 cfu/100 mL, not to be exceeded by more than 10 percent of samples within a calendar month (ISWEBE 2018).
Objective/Criterion Reference: Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site(s), station(s): 202FRE100 (Frenchmans Creek at Bordeaux Lane).
Temporal Representation: The samples were collected between the days of 2019-11-21 and 2020-06-23 .
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 148781, Indicator Bacteria
Region 2     
Frenchmans Creek (San Mateo)
 
LOE ID: 300320
 
Pollutant: Enterococcus
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: STV
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 2
Number of Exceedances: 1
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP RWB2 Monitoring data for Frenchmans Creek (San Mateo) to determine beneficial use support and the results are as follows: 1 of the 2 samples exceeded the Statistical Threshold Value (STV) water quality threshold for Enterococcus. The STV is based on a 10% exceedance rate that is calculated monthly.
Data Reference: Field, Habitat, Tissue, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: The bacteria water quality objective to protect the REC-1 beneficial use where the salinity is 1 ppth or higher 95 percent or more of the time applies a Statistical Threshold Value to enterococcus of 110 cfu/100 mL, not to be exceeded by more than 10 percent of samples collected within in a calendar month. (ISWEBE 2018)
Objective/Criterion Reference: Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site(s), station(s): 202FRE004 (Frenchman's Creek at Half Moon Bay Beach, at creek mouth).
Temporal Representation: The samples were collected between the days of 2020-03-16 and 2020-06-23 .
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 148781, Indicator Bacteria
Region 2     
Frenchmans Creek (San Mateo)
 
LOE ID: 300417
 
Pollutant: Enterococcus
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: STV
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 2
Number of Exceedances: 2
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP RWB2 Monitoring data for Frenchmans Creek (San Mateo) to determine beneficial use support and the results are as follows: 2 of the 2 samples exceeded the Statistical Threshold Value (STV) water quality threshold for Enterococcus. The STV is based on a 10% exceedance rate that is calculated monthly.
Data Reference: Field, Habitat, Tissue, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: The bacteria water quality objective to protect the REC-1 beneficial use where the salinity is 1 ppth or higher 95 percent or more of the time applies a Statistical Threshold Value to enterococcus of 110 cfu/100 mL, not to be exceeded by more than 10 percent of samples collected within in a calendar month. (ISWEBE 2018)
Objective/Criterion Reference: Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site(s), station(s): 202FRE002 (Frenchman's Creek at Half Moon Bay Beach, ~ 40m d/s of creek mouth).
Temporal Representation: The samples were collected between the days of 2020-03-16 and 2020-06-23 .
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 148781, Indicator Bacteria
Region 2     
Frenchmans Creek (San Mateo)
 
LOE ID: 300473
 
Pollutant: Escherichia coli (E. coli)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: STV
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP RWB2 Monitoring data for Frenchmans Creek (San Mateo) to determine beneficial use support and the results are as follows: 0 of the 1 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.
Data Reference: Field, Habitat, Tissue, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: The bacteria water quality objective to protect the REC-1 beneficial use where the salinity is less than 1 parts per thousand 95 percent or more of the time applies a statistical threshold value to E. coli of 320 cfu/100 mL, not to be exceeded by more than 10 percent of samples within a calendar month (ISWEBE 2018).
Objective/Criterion Reference: Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site(s), station(s): 202FRE010 (Frenchmans Creek 50m u/s of beach).
Temporal Representation: The samples were collected between the days of 2019-11-21 and 2019-11-21 .
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.