| Water Body Name: | Unnamed tributary to Medea Creek Reach 2 (Ventura County) |
| Water Body ID: | CAR4042300020210322038359 |
| Water Body Type: | River & Stream |
DECISION ID |
151088 |
Region 4 |
Unnamed tributary to Medea Creek Reach 2 (Ventura County) |
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| Pollutant: | Benthic Community Effects |
| 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: | Benthic Community Effects are being considered for placement on the CWA section 303(d) List under sections 3.9 of the Listing Policy. Under section 3.9, additional lines of evidence (LOEs) associating the Benthic Community Effects decision with a water or sediment concentration of pollutants other than benthic-macroinvertebrate bioassessment or habitat assessment LOEs are necessary to place a water body on the 303(d) List for Benthic Community Effects. One line of evidence evaluating benthic-macroinvertebrate bioassessment data is/are available in the administrative record to assess this indicator. One of one benthic-macroinvertebrate samples exceed the California Stream Condition Index (CSCI) impairment threshold. However, a minimum of two benthic-macroinvertebrate samples are needed to assess listing status. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing Benthic Community Effects in this waterbody segment 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 one benthic-macroinvertebrate bioassessment samples had CSCI scores below 0.79. The available information is insufficient to determine whether the waterbody/pollutant combination should be placed on the 303(d) List of impaired waters at this time. 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: | 305343 | ||||
| Pollutant: | Benthic-Macroinvertebrate Bioassessments | ||||
| LOE Subgroup: | Population/Community Degradation | ||||
| Matrix: | Water | ||||
| Fraction: | None | ||||
| Beneficial Use: | Warm Freshwater Habitat | ||||
| Number of Samples: | 1 | ||||
| Number of Exceedances: | 1 | ||||
| Data and Information Type: | Benthic macroinvertebrate surveys | ||||
| Data Used to Assess Water Quality: | Water Board staff assessed data for 404R4S009 to determine beneficial use support and the results are as follows: 1 of 1 samples exceeded the threshold. CSCI scores were from 0.58002046 to 0.58002046. | ||||
| Data Reference: | California Stream Condition Index (CSCI) Scores for the 2024 Integrated Report for Region 4. | ||||
| SWAMP Data: | SWAMP | ||||
| Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce significant alterations in population or community ecology or receiving water biota. In addition, the health and life history characteristics of aquatic organisms in waters affected by controllable water quality factors shall not differ significantly from those for the same waters in areas unaffected by controllable water quality factors. | ||||
| Objective/Criterion Reference: | Water Quality Control Plan Los Angeles Region R4 Basin Plan | ||||
| Evaluation Guideline: | The California Stream Condition Index (CSCI) is a biological scoring tool that helps aquatic resource managers translate complex data about benthic macroinvertebrates found living in a stream into an overall measure of stream health. The CSCI score is calculated by comparing the expected condition with actual (observed) results (Rehn, A.C. et al., 2015). CSCI scores range from 0 (highly degraded) to greater than 1 (equivalent to reference). CSCI scoring of biological condition are as follows (per the scientific paper supporting the development of the CSCI scoring tool): greater than or equal to 0.92 = likely intact condition, 0.91 to 0.80 = possibly altered condition, 0.79 to 0.63 = likely altered condition, less than or equal to 0.62 = very likely altered condition. Sites with scores below 0.79 are considered to have exceeded the water quality objective for the aquatic life beneficial use. | ||||
| Guideline Reference: | Bioassessment in complex environments: designing an index for consistent meaning in different settings | ||||
| Spatial Representation: | Samples were collected from station 404R4S009. | ||||
| Temporal Representation: | Samples were collected from 4/30/2015 to 4/30/2015. | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Data were collected using Surface Water Ambient Monitoring Program protocols | ||||
| QAPP Information Reference(s): | This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements. | ||||
DECISION ID |
149996 |
Region 4 |
Unnamed tributary to Medea Creek Reach 2 (Ventura County) |
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| Pollutant: | Nitrogen, Nitrate |
| 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 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. 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 in the Water Quality Limited Segments category. 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. 0 of 16 samples exceeded the objective and this does not exceed the allowable frequency listed in Table 3.1 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 because applicable water quality standards are not being exceeded. |
| State Board Review of Regional Board Conclusion and Recommendation: | |
| State Board Decision Recommendation: | |
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| LOE ID: | 302367 | ||||
| Pollutant: | Nitrogen, Nitrate | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | Dissolved | ||||
| Beneficial Use: | Warm Freshwater Habitat | ||||
| Number of Samples: | 16 | ||||
| Number of Exceedances: | 0 | ||||
| Data and Information Type: | PHYSICAL/CHEMICAL MONITORING | ||||
| Data Used to Assess Water Quality: | Water Board staff assessed Water Quality Monitoring in the Malibu Creek Water data for Unnamed tributary to Medea Creek Reach 2 (Ventura County) to determine beneficial use support and results are as follows: 0 of 16 samples exceeded the water quality threshold for Nitrate as N. | ||||
| Data Reference: | Field, Habitat 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: | The Water Quality Control Plan for the Los Angeles Region (page 3-34) states that: Waters shall not exceed 10 mg/L as nitrate-nitrogen (NO3-N). | ||||
| Objective/Criterion Reference: | Water Quality Control Plan Los Angeles Region R4 Basin Plan | ||||
| Evaluation Guideline: | |||||
| Guideline Reference: | |||||
| Spatial Representation: | The samples were collected at 1 monitoring site: WQ_MEDEA_D (Medea D). | ||||
| Temporal Representation: | The samples were collected between the dates of 2017-08-29 and 2019-03-05 | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Los Angeles Regional Water Quality Control Board. 2016. Coordinated Integrated Monitoring Program for Malibu Creek Watershed. | ||||
| QAPP Information Reference(s): | Coordinated Integrated Monitoring Program for Malibu Creek Watershed | ||||
DECISION ID |
140664 |
Region 4 |
Unnamed tributary to Medea Creek Reach 2 (Ventura County) |
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| Pollutant: | Temperature, water |
| 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: | |
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| LOE ID: | 266939 | ||||
| Pollutant: | Temperature, water | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | Not Recorded | ||||
| Beneficial Use: | Warm Freshwater Habitat | ||||
| Number of Samples: | 17 | ||||
| Number of Exceedances: | 0 | ||||
| Data and Information Type: | PHYSICAL/CHEMICAL MONITORING | ||||
| Data Used to Assess Water Quality: | Water Board staff assessed Water Quality Monitoring in the Malibu Creek Water data for Unnamed tributary to Medea Creek Reach 2 (Ventura County) to determine beneficial use support and results are as follows: 0 of 17 samples exceeded the water quality threshold for Temperature. | ||||
| Data Reference: | Field, Habitat 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: | The Water Quality Control Plan for the Los Angeles Region (page 3-45) states that: For waters designated WARM, water temperature shall not be altered by more than 5 °F above the natural temperature. At no time shall these WARM-designated waters be raised above 80 °F as a result of waste discharges. | ||||
| Objective/Criterion Reference: | Water Quality Control Plan Los Angeles Region R4 Basin Plan | ||||
| Evaluation Guideline: | |||||
| Guideline Reference: | |||||
| Spatial Representation: | The samples were collected at 1 monitoring site: WQ_MEDEA_D (Medea D). | ||||
| Temporal Representation: | The samples were collected between the dates of 2017-08-29 and 2019-03-05 | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Los Angeles Regional Water Quality Control Board. 2016. Coordinated Integrated Monitoring Program for Malibu Creek Watershed. | ||||
| QAPP Information Reference(s): | Coordinated Integrated Monitoring Program for Malibu Creek Watershed | ||||
DECISION ID |
140663 |
Region 4 |
Unnamed tributary to Medea Creek Reach 2 (Ventura County) |
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| Pollutant: | pH |
| 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: | |
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| LOE ID: | 265110 | ||||
| Pollutant: | pH | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | None | ||||
| Beneficial Use: | Warm Freshwater Habitat | ||||
| Number of Samples: | 17 | ||||
| Number of Exceedances: | 0 | ||||
| Data and Information Type: | PHYSICAL/CHEMICAL MONITORING | ||||
| Data Used to Assess Water Quality: | Water Board staff assessed Water Quality Monitoring in the Malibu Creek Water data for Unnamed tributary to Medea Creek Reach 2 (Ventura County) to determine beneficial use support and results are as follows: 0 of 17 samples exceeded the water quality threshold for pH. | ||||
| Data Reference: | Field, Habitat 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: | Water Quality Control Plan, Los Angeles Basin: the pH for inland surface waters, bays, or estuaries shall not be depressed below 6.5 or raised above 8.5 as a result of waste discharges. | ||||
| Objective/Criterion Reference: | Water Quality Control Plan Los Angeles Region R4 Basin Plan | ||||
| Evaluation Guideline: | |||||
| Guideline Reference: | |||||
| Spatial Representation: | The samples were collected at 1 monitoring site: WQ_MEDEA_D (Medea D). | ||||
| Temporal Representation: | The samples were collected between the dates of 2017-08-29 and 2019-03-05 | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Los Angeles Regional Water Quality Control Board. 2016. Coordinated Integrated Monitoring Program for Malibu Creek Watershed. | ||||
| QAPP Information Reference(s): | Coordinated Integrated Monitoring Program for Malibu Creek Watershed | ||||
DECISION ID |
151957 |
Region 4 |
Unnamed tributary to Medea Creek Reach 2 (Ventura County) |
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| Pollutant: | Oxygen, Dissolved |
| Final Listing Decision: | List on 303(d) list (TMDL required list) |
| Last Listing Cycle's Final Listing Decision: | New Decision |
| Revision Status | Revised |
| Sources: | A Source Unknown |
| Expected TMDL Completion Date: | 2037 |
| 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. One line of evidence is available in the administrative record to assess this pollutant. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of 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. 15 of 17 samples exceed the objective and this exceeds the allowable frequency listed 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 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: | 308467 | ||||
| Pollutant: | Oxygen, Dissolved | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | Total | ||||
| Beneficial Use: | Warm Freshwater Habitat | ||||
| Number of Samples: | 17 | ||||
| Number of Exceedances: | 15 | ||||
| Data and Information Type: | PHYSICAL/CHEMICAL MONITORING | ||||
| Data Used to Assess Water Quality: | Water Board staff assessed Water Quality Monitoring in the Malibu Creek Water data for Unnamed tributary to Medea Creek Reach 2 (Ventura County) to determine beneficial use support and results are as follows: 15 of 17 samples exceeded the water quality threshold for Oxygen, Dissolved. | ||||
| Data Reference: | Field, Habitat 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: | The Water Quality Control Plan for the Los Angeles Region (page 3-39) states that: The dissolved oxygen content of all surface waters designated as WARM shall not be depressed below 5 mg/L as a result of waste discharges. | ||||
| Objective/Criterion Reference: | Water Quality Control Plan Los Angeles Region R4 Basin Plan | ||||
| Evaluation Guideline: | |||||
| Guideline Reference: | |||||
| Spatial Representation: | The samples were collected at 1 monitoring site: WQ_MEDEA_D (Medea D). | ||||
| Temporal Representation: | The samples were collected between the dates of 2017-08-29 and 2019-03-05 | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Los Angeles Regional Water Quality Control Board. 2016. Coordinated Integrated Monitoring Program for Malibu Creek Watershed. | ||||
| QAPP Information Reference(s): | Coordinated Integrated Monitoring Program for Malibu Creek Watershed | ||||