Water Quality Objective/Criterion: |
All waters shall be maintained free of toxic substances that are lethal to or that produce other detrimental responses in aquatic organisms.
There shall be no chronic toxicity in ambient waters. Chronic toxicity is a detrimental biological effect on growth rate, reproduction, fertilization success, larval development, population abundance, community composition, or any other relevant measure of the health of an organism, population, or community. |
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DECISION ID |
9807 |
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Pollutant: |
Toxicity |
Final Listing Decision: |
List on 303(d) list (TMDL required list) |
Last Listing Cycle's Final Listing Decision: |
New Decision |
Revision Status |
Revised |
Sources: |
Source Unknown |
Expected TMDL Completion Date: |
2021 |
Impairment from Pollutant or Pollution: |
Pollutant |
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Weight of Evidence: |
This pollutant is being considered for listing under section 3.6 of the Listing Policy. Under section 3.6 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. This water body experiences toxicity.
Based on the readily available data for this water body, the weight of evidence indicates that there is sufficient justification available in favor of adding this water segment-pollutant combination to the section 303(d) list in the Water Quality Limited Segments category.
This conclusion is based on the staff findings that:
1. The data concerning current conditions and supporting the listing decision satisfy the data quality requirements of section 6.1.4 of the Policy.
2. The data used satisfy the data quantity requirements of section 6.1.5 of the Policy.
3. Two out of 4 water samples exhibited significant chronic toxicity to Ceriodaphnia and two other test organisms showed diminished growth. The number of samples with detected significant water toxicity exceeds the allowable frequency listed in Table 3.1 of the Listing Policy and the sediment toxicity is also observed.
4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. |
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RWQCB Board Decision / Staff Recommendation: |
After review of the available data and information, Water Board staff concludes that the water body-pollutant combination should be added to the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem. |
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SWRCB Board Decision / Staff Recommendation: |
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USEPA Decision: |
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LOE ID: |
8541 |
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Pollutant: |
Toxicity |
LOE Subgroup: |
Pollutant-Water |
Matrix: |
Water |
Fraction: |
None |
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Beneficial Use: |
Cold Freshwater Habitat |
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Number of Samples: |
4 |
Number of Exceedances: |
2 |
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Data and Information Type: |
TOXICITY TESTING |
Data Used to Assess Water Quality: |
Four samples were collected in 2003 to evaluate water toxicity at two monitoring locations at the mouth of Mount Diablo Creek and at Mitchell Canyon, the upstream tributary. The toxicity tests included survival and reproduction of Ceriodaphnia, survival and growth of fathead minnow, and growth of Selenastrum.
Statistically significant chronic effects on Ceriodaphnia reproduction were observed in 2 out of 4 samples collected at both locations during winter wet season. In addition, one sample caused significant mortality and another caused a decrease in growth in fathead minnow. Selenastrum growth was also significantly reduced in one sample collected during winter wet season. |
Data Reference: |
Water Quality Monitoring and Bioassessment in Four San Francisco Bay Region Watersheds in 2003-2004: Kirker Creek, Mt. Diablo Creek, Petaluma River, and San Mateo Creek. Surface Water Monitoring Program, San Francisco Bay Regional Water Quality Control Board, Oakland. CA |
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Water Quality Objective/Criterion: |
All waters shall be maintained free of toxic substances that are lethal to or that produce other detrimental responses in aquatic organisms.
There shall be no chronic toxicity in ambient waters. Chronic toxicity is a detrimental biological effect on growth rate, reproduction, fertilization success, larval development, population abundance, community composition, or any other relevant measure of the health of an organism, population, or community. |
Objective/Criterion Reference: |
San Francisco Bay Basin (Region 2) Water Quality Control Plan (Basin Plan) |
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Evaluation Guideline: |
Water toxicity was evaluated according to the SWAMP methodology. The U.S.EPA whole effluent toxicity protocol (U.S.EPA 1994) was used to test the effect of water samples on three freshwater test organisms. Statistical evaluation (alpha = 0.05) and a default threshold of 80% of the control value were used to establish whether water exhibited significant toxicity adversely impacting aquatic organisms. |
Guideline Reference: |
Revised approach to toxicity test acceptability criteria using a statistical performance assessment. Environmental Toxicology and Chemistry, vol. 16, No. 6, pp 13221329 |
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Short-Term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms. EPA/600/4-91/002. Third Edition. July 1994 |
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Spatial Representation: |
Data were collected at one sampling location, MTD010, on two (2) occasions, representative of the lower reach of the creek. Data were collected at one sampling location, MTD100, on two occasions, representative of the upstream tributary. |
Temporal Representation: |
SWAMP samples were collected during winter wet season (January) and spring season (April) of 2003. |
Environmental Conditions: |
The lower reach data are representative of heavily urbanized area dominated by the city of Concord. The tributary stream of Mitchell Canyon drains in its upper portion the area within the Mt. Diablo State Park. |
QAPP Information: |
All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB, 2002). |
QAPP Information Reference(s): |
Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
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