| Water Body Name: | Carneros Creek subwatershed (Napa County, tributary to Napa River-tidal) |
| Water Body ID: | CAR2065007020210615055819 |
| Water Body Type: | River & Stream |
DECISION ID |
148493 |
Region 2 |
Carneros 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: | Agriculture-grazing | Onsite Wastewater Systems (Septic Tanks) |
| TMDL Name: | Napa River Pathogens |
| TMDL Project Code: | 60 |
| Date TMDL Approved by USEPA: | 11/20/0006 |
| Impairment from Pollutant or Pollution: | Pollutant |
| Regional Board Conclusion: | This pollutant is being considered for placement on the CWA section 303(d) List under sections 2.2 and 3.3 of the Listing Policy. Under section 3.3 of the Policy, a minimum of one line of evidence is needed to assess listing status. Three lines of evidence are available in the administrative record to assess this pollutant. Five out of six samples exceeded the statistical threshold value objective. 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 in the Being Addressed by TMDL portion of the CWA 303(d) List because a TMDL has been completed and approved by RWQCB and USEPA, and is expected to result in attainment of the standard. The TMDL covers the watershed that includes this water body. 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. Five out of six samples exceeded the statistical threshold value objective and these exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. The Napa River Pathogen TMDL was approved by USEPA in November 2006. 5. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. |
| Regional Board Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should 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: | |
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| LOE ID: | 300247 | ||||
| Pollutant: | Escherichia coli (E. coli) | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | GeoMean | ||||
| Beneficial Use: | Water Contact Recreation | ||||
| Number of Samples: | 1 | ||||
| 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 Carneros Creek subwatershed (Napa County, tributary to Napa River-tidal) to determine beneficial use support and the results are as follows: 1 of the 1 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): 206CAR200 (Carneros Creek at Whithers Rd). | ||||
| Temporal Representation: | The samples were collected between the days of 2017-01-11 and 2017-08-01 . | ||||
| 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: | 300352 | ||||
| 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: | 5 | ||||
| Data and Information Type: | PATHOGEN MONITORING | ||||
| Data Used to Assess Water Quality: | Water Board staff assessed SWAMP RWB2 Monitoring data for Carneros Creek subwatershed (Napa County, tributary to Napa River-tidal) to determine beneficial use support and the results are as follows: 5 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): 206CAR200 (Carneros Creek at Whithers Rd). | ||||
| Temporal Representation: | The samples were collected between the days of 2017-01-11 and 2017-08-01 . | ||||
| 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. | ||||