| Pollutant: |
Toxicity |
| 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: |
Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available |
| |
| 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: |
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 139559, Toxicity
|
Region 4 |
Gabbert Canyon Drain (tributary to Arroyo Las Posas) |
|
| |
| LOE ID: |
244566 |
| |
| Pollutant: |
Toxicity |
| LOE Subgroup: |
Toxicity |
| Matrix: |
Water |
| Fraction: |
None |
| |
| Beneficial Use: |
Cold Freshwater Habitat |
| |
| Number of Samples: |
4 |
| Number of Exceedances: |
0 |
| |
| Data and Information Type: |
TOXICITY TESTING |
| Data Used to Assess Water Quality: |
0 of the 4 samples collected by Ventura Countywide Stormwater Quality Mgmt Program for Gabbert Canyon Drain (tributary to Arroyo Las Posas) exhibited toxicity. A sample may have multiple toxicity test results, but will only be counted once. A sample is defined as being collected on the same day and the same location. The following organisms and parameters were utilized for the toxicity tests: Selenastrum capricornutum for Total Cell Count. |
| Data Reference: |
Field, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4. |
| |
| SWAMP Data: |
Non-SWAMP |
| |
| Water Quality Objective/Criterion: |
All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in, human, plant, animal, or aquatic life. |
| Objective/Criterion Reference: |
Water Quality Control Plan Los Angeles Region R4 Basin Plan |
| |
| Evaluation Guideline: |
The sample is toxic when the response of the organisms exposed to the sample is significantly different (worse) than the response of the organisms exposed to the laboratory control based on statistical hypothesis testing. An exceedance is counted when the significant effect code is “Significant; Less Similarity,” which means that the sample result is significantly different than the control result, and the percent effect is greater than the evaluation threshold. The default evaluation threshold is 20% unless otherwise stated. |
| Guideline Reference: |
Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms. Fourth Edition. Office of Water, U.S. Environmental Protection Agency. Washington, D.C. EPA-821-R-02-013 |
| |
| Spatial Representation: |
The samples were collected at monitoring site: MO-MPK ( MO-MPK ). |
| Temporal Representation: |
The samples were collected between the dates of 2016-10-28 and 2019-11-27. |
| Environmental Conditions: |
|
| QAPP Information: |
Ventura County . 2006. Ventura Countywide Stormwater Monitoring Program DATA QUALITY EVALUATION STANDARD OPERATING PROCEDURES (SOPs), And Stormwater Program: Water Quality Monitoring Standard Operating Procedures 2009 - 2014.. |
| QAPP Information Reference(s): |
Ventura Countywide Stormwater Monitoring Program DATA QUALITY EVALUATION STANDARD OPERATING PROCEDURES (SOPs), And
Stormwater Program: Water Quality Monitoring Standard Operating Procedures
2009 - 2014. |
| |
Line of Evidence (LOE) for Decision ID 139559, Toxicity
|
Region 4 |
Gabbert Canyon Drain (tributary to Arroyo Las Posas) |
|
| |
| LOE ID: |
244567 |
| |
| Pollutant: |
Toxicity |
| LOE Subgroup: |
Toxicity |
| Matrix: |
Water |
| Fraction: |
None |
| |
| Beneficial Use: |
Warm Freshwater Habitat |
| |
| Number of Samples: |
4 |
| Number of Exceedances: |
0 |
| |
| Data and Information Type: |
TOXICITY TESTING |
| Data Used to Assess Water Quality: |
0 of the 4 samples collected by Ventura Countywide Stormwater Quality Mgmt Program for Gabbert Canyon Drain (tributary to Arroyo Las Posas) exhibited toxicity. A sample may have multiple toxicity test results, but will only be counted once. A sample is defined as being collected on the same day and the same location. The following organisms and parameters were utilized for the toxicity tests: Selenastrum capricornutum for Total Cell Count. |
| Data Reference: |
Field, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4. |
| |
| SWAMP Data: |
Non-SWAMP |
| |
| Water Quality Objective/Criterion: |
All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in, human, plant, animal, or aquatic life. |
| Objective/Criterion Reference: |
Water Quality Control Plan Los Angeles Region R4 Basin Plan |
| |
| Evaluation Guideline: |
The sample is toxic when the response of the organisms exposed to the sample is significantly different (worse) than the response of the organisms exposed to the laboratory control based on statistical hypothesis testing. An exceedance is counted when the significant effect code is “Significant; Less Similarity,” which means that the sample result is significantly different than the control result, and the percent effect is greater than the evaluation threshold. The default evaluation threshold is 20% unless otherwise stated. |
| Guideline Reference: |
Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms. Fourth Edition. Office of Water, U.S. Environmental Protection Agency. Washington, D.C. EPA-821-R-02-013 |
| |
| Spatial Representation: |
The samples were collected at monitoring site: MO-MPK ( MO-MPK ). |
| Temporal Representation: |
The samples were collected between the dates of 2016-10-28 and 2019-11-27. |
| Environmental Conditions: |
|
| QAPP Information: |
Ventura County . 2006. Ventura Countywide Stormwater Monitoring Program DATA QUALITY EVALUATION STANDARD OPERATING PROCEDURES (SOPs), And Stormwater Program: Water Quality Monitoring Standard Operating Procedures 2009 - 2014.. |
| QAPP Information Reference(s): |
Ventura Countywide Stormwater Monitoring Program DATA QUALITY EVALUATION STANDARD OPERATING PROCEDURES (SOPs), And
Stormwater Program: Water Quality Monitoring Standard Operating Procedures
2009 - 2014. |
| |