| Water Body Name: | Fagan Creek subwatershed (Napa County, tributary to Napa River - tidal) |
| Water Body ID: | CAR2065004020210520035381 |
| Water Body Type: | River & Stream |
DECISION ID |
148777 |
Region 2 |
Fagan Creek subwatershed (Napa County, tributary to Napa River - tidal) |
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| 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: | Napa River Pathogens |
| TMDL Project Code: | 60 |
| Date TMDL Approved by USEPA: | 02/29/2008 |
| Impairment from Pollutant or Pollution: | Pollutant |
| Regional Board Conclusion: | This pollutant is being considered for placement on the CWA section 303(d) List under section 3.11 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. Fagan Creek is a tributary to Napa River. The Napa River and its tributaries, including Fagan Creek, are impaired by indicator bacteria (pathogens) and subject to the Napa River Pathogen 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. Fagan Creek is a tributary to Napa River which is impaired by pathogens. E. coli measured at several Napa River watershed locations including Fagan Creek during the development of the Napa River Pathogen TMDL showed moderate but widespread exceedances of water quality objectives, indicating pathogen impairment of REC-1 and REC-2 beneficial uses throughout the watershed. The sources of pathogens include numerous onsite wastewater treatment systems, confined animal facilities, grazing lands and municipal runoff. These pathogen sources exist throughout the Napa River watershed, including the Fagan Creek watershed. 2017 monitoring data indicate improvement is still needed throughout the watershed before TMDL targets are met. 2. The TMDL implementation plan states “The overall intent of this implementation plan is to restore and protect beneficial uses of the Napa River and its tributaries by reducing pathogen loadings. Potential pathogen sources in the watershed include: septic systems, sanitary sewer line failure, municipal runoff, livestock, and wildlife.” The TMDL implementation actions (e.g., the Conditional Waiver Program from Grazing Operations in the Napa River watershed and the NPDES general stormwater permit), were written to include the entire Napa River watershed. As such, the Napa River Pathogen TMDL already applies to the Fagan Creek subwatershed. Sources of pathogens exist in the Fagan Creek subwatershed and contribute to exceedances of E.coli objectives for water contact recreation. Current conditions indicate that water quality in the Creek is impaired. 3. Eighty-six out of two hundred thirty-four samples collected collectively in the Napa River tributaries and eight of ten samples collected in Fagan Creek during post-TMDL sampling exceeded E.coli objectives for REC-1. The water quality data are insufficient to determine that water quality have been improved and water quality objectives are met in the Napa River watershed in general and in Fagan Creek subwatershed in particular. 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 Fagan Creek subwatershed was included in the Napa River Pathogen TMDL assessment and determined to be a source of pathogens in the Napa River watershed. The TMDL assessment included a rigorous technical review, the public participation process, and approval by U.S. EPA. Additionally, the data analysis for the TMDL made use of the E. coli objectives that were in place at the time of TMDL development. Although these objectives have been subsequently updated, exceedances of the older objectives would also constitute exceedances of the revised (lower) objectives. |
| 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: | 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 Fagan Creek subwatershed was included in the Napa River Pathogen TMDL assessment and determined to be a source of pathogens in the Napa River watershed. The TMDL assessment included a rigorous technical review, the public participation process, and approval by U.S. EPA. Additionally, the data analysis for the TMDL made use of the E. coli objectives that were in place at the time of TMDL development. Although these objectives have been subsequently updated, exceedances of the older objectives would also constitute exceedances of the revised (lower) objectives. |
| State Board Decision Recommendation: | |
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| LOE ID: | 300445 | ||||
| Pollutant: | Escherichia coli (E. coli) | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | GeoMean | ||||
| 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 Fagan Creek subwatershed (Napa County, tributary to Napa River - tidal) to determine beneficial use support and the results are as follows: 2 of the 2 samples exceeded the geomean water quality threshold for E. coli. This is a six week rolling geomean that is calculated weekly. | ||||
| 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 for waters where the salinity is equal to or less than 1 part per thousand 95 percent or more of the time applies a rolling six-week geometric mean of E. coli, not to exceed 100 cfu/100 mL (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): 206FGN100 (Fagan Creek at S. Kelley Rd). | ||||
| Temporal Representation: | The samples were collected between the days of 2017-01-11 and 2017-08-08 . | ||||
| 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. | ||||
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| LOE ID: | 300511 | ||||
| Pollutant: | Escherichia coli (E. coli) | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | STV | ||||
| Beneficial Use: | Water Contact Recreation | ||||
| Number of Samples: | 6 | ||||
| Number of Exceedances: | 4 | ||||
| Data and Information Type: | PATHOGEN MONITORING | ||||
| Data Used to Assess Water Quality: | Water Board staff assessed SWAMP RWB2 Monitoring data for Fagan Creek subwatershed (Napa County, tributary to Napa River - tidal) to determine beneficial use support and the results are as follows: 4 of the 6 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): 206FGN100 (Fagan Creek at S. Kelley Rd). | ||||
| Temporal Representation: | The samples were collected between the days of 2017-01-11 and 2017-08-08 . | ||||
| 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. | ||||