| Water Body Name: | Unnamed tributary of Mammoth Creek near Timber Creek Road |
| Water Body ID: | CAR6031005020230504037862 |
| Water Body Type: | River & Stream |
DECISION ID |
170631 |
Region 6 |
Unnamed tributary of Mammoth Creek near Timber Creek Road |
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| Pollutant: | Mercury |
| 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: | 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. Three lines of evidence are available in the administrative record to assess this pollutant. One of the 2 water samples exceed the COMM and MUN criteria. Zero of 2 water samples exceeded the COLD criteria. 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 2 water samples exceed the COMM and MUN criteria. Zero of 2 water samples exceeded the COLD criteria. This does not exceed the allowable number of exceedances 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. 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: | |
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| LOE ID: | 338685 | ||||
| Pollutant: | Mercury | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | Total | ||||
| Beneficial Use: | Cold Freshwater Habitat | ||||
| Number of Samples: | 2 | ||||
| Number of Exceedances: | 0 | ||||
| Data and Information Type: | PHYSICAL/CHEMICAL MONITORING | ||||
| Data Used to Assess Water Quality: | Water Board staff assessed Upper Owens River Water Quality Project data for Unnamed tributary of Mammoth Creek near Timber Creek Road to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Mercury. | ||||
| Data Reference: | WQ from the Upper Owens River Water Quality Program for the 2026 Integrated Report in Region 6 | ||||
| SWAMP Data: | Non-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 (Water Quality Control Plan, Lahontan Region). | ||||
| Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended) | ||||
| Evaluation Guideline: | National Recommended Water Quality Criteria Continuous Concentrations (4-day average concentrations) for freshwater aquatic organisms exposure to total mercury is 0.77 ug/L. | ||||
| Guideline Reference: | National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016. | ||||
| Spatial Representation: | The samples were collected at 1 monitoring site: 160MAM044 (Upstream from Club Drive culvert). | ||||
| Temporal Representation: | The samples were collected between the dates of 2013-04-17 and 2013-06-05 | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Quality Assurance Project Plan (QAPP) for Upper Owens River Water Quality Project Data | ||||
| QAPP Information Reference(s): | Quality Assurance Project Plan (QAPP) for Upper Owens River Water Quality Project Data | ||||
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| LOE ID: | 338696 | ||||
| Pollutant: | Mercury | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | Total | ||||
| Beneficial Use: | Commercial or recreational collection of fish, shellfish, or organisms | ||||
| Number of Samples: | 2 | ||||
| Number of Exceedances: | 1 | ||||
| Data and Information Type: | PHYSICAL/CHEMICAL MONITORING | ||||
| Data Used to Assess Water Quality: | Water Board staff assessed Upper Owens River Water Quality Project data for Unnamed tributary of Mammoth Creek near Timber Creek Road to determine beneficial use support and results are as follows: 1 of 2 samples exceeded the water quality threshold for Mercury. | ||||
| Data Reference: | WQ from the Upper Owens River Water Quality Program for the 2026 Integrated Report in Region 6 | ||||
| SWAMP Data: | Non-SWAMP | ||||
| Water Quality Objective/Criterion: | The Mercury criteria for the protection of human health from consumption of organisms only is 0.051 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: 160MAM044 (Upstream from Club Drive culvert). | ||||
| Temporal Representation: | The samples were collected between the dates of 2013-04-17 and 2013-06-05 | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Quality Assurance Project Plan (QAPP) for Upper Owens River Water Quality Project Data | ||||
| QAPP Information Reference(s): | Quality Assurance Project Plan (QAPP) for Upper Owens River Water Quality Project Data | ||||
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| LOE ID: | 338693 | ||||
| Pollutant: | Mercury | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | Total | ||||
| Beneficial Use: | Municipal & Domestic Supply | ||||
| Number of Samples: | 2 | ||||
| Number of Exceedances: | 1 | ||||
| Data and Information Type: | PHYSICAL/CHEMICAL MONITORING | ||||
| Data Used to Assess Water Quality: | Water Board staff assessed Upper Owens River Water Quality Project data for Unnamed tributary of Mammoth Creek near Timber Creek Road to determine beneficial use support and results are as follows: 1 of 2 samples exceeded the water quality threshold for Mercury. | ||||
| Data Reference: | WQ from the Upper Owens River Water Quality Program for the 2026 Integrated Report in Region 6 | ||||
| SWAMP Data: | Non-SWAMP | ||||
| Water Quality Objective/Criterion: | The mercury criteria for the protection of human health from the consumption of water and organisms is 0.050 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: 160MAM044 (Upstream from Club Drive culvert). | ||||
| Temporal Representation: | The samples were collected between the dates of 2013-04-17 and 2013-06-05 | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Quality Assurance Project Plan (QAPP) for Upper Owens River Water Quality Project Data | ||||
| QAPP Information Reference(s): | Quality Assurance Project Plan (QAPP) for Upper Owens River Water Quality Project Data | ||||