| Water Body Name: | San Gabriel River Reach 4 (Morris Dam to Ramona Blvd) |
| Water Body ID: | CAR4053100020110720103544 |
| Water Body Type: | River & Stream |
DECISION ID |
99163 |
Region 4 |
San Gabriel River Reach 4 (Morris Dam to Ramona Blvd) |
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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: | Do Not List on 303(d) list (TMDL required list)(2016) |
| Revision Status | Original |
| Impairment from Pollutant or Pollution: | Pollutant |
| Regional Board Conclusion: | Benthic Community Effects is being considered for placement on the CWA section 303(d) List under sections 3.9 of the Listing Policy. Under section 3.9, an additional line of evidence associating the Benthic Community Effects with a water or sediment concentration of pollutants is necessary to assess listing status.Three samples were collected from the San Gabriel River over three years. Three of the three samples collected had an IBI score below 40. However, there is no pollutant exceeding standards with which to associate these IBI scores with.
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 water 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.Three samples were collected from the San Gabriel River over three years. Three of the three samples collected had an IBI score below 40. However, as required under section 3.9 of the Listing Policy, pollutant(s) could not be directly associated with the Benthic Community Effects. 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: | After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board. |
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| LOE ID: | 87972 | ||||
| Pollutant: | Benthic-Macroinvertebrate Bioassessments | ||||
| LOE Subgroup: | Population/Community Degradation | ||||
| Matrix: | Water | ||||
| Fraction: | Not Recorded | ||||
| Beneficial Use: | Warm Freshwater Habitat | ||||
| Number of Samples: | 3 | ||||
| Number of Exceedances: | 3 | ||||
| Data and Information Type: | Benthic macroinvertebrate surveys | ||||
| Data Used to Assess Water Quality: | Three samples were collected from the San Gabriel River over three years. Three of the three samples collected had an IBI score below 40. The scores were 20 (2006), 25 (2007), and 18 (2008). | ||||
| Data Reference: | Bioassessment Monitoring Report in Los Angeles County, 2006-2008. | ||||
| 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 or animal, or aquatic life. Compliance with this objective will be determined by use of indicator organisms, analysis of species diversity, population density, growth anomalies, bioassays of appropriate duration or other appropriate methods as specified by the State or Regional Board. Region 4 Basin Plan. | ||||
| Objective/Criterion Reference: | Water Quality Control Plan Los Angeles Region R4 Basin Plan | ||||
| Evaluation Guideline: | The IBI is a multi-metric assessment that employs biological metrics that respond to a habitat or water quality impairment. Each of the biological metrics measured at a site are converted to an IBI score then summed. These cumulative scores are then ranked. For the Southern California IBI, sites with scores below 40 are considered to have impaired conditions. | ||||
| Guideline Reference: | Development of a Benthic Index of Biotic Integrity (B-IBI) for Wadeable Streams in Northern Coastal California and its Application to Regional 305(b) Assessment | ||||
| Spatial Representation: | The samples were collected at station 3 Upper San Gabriel River below Morris Reservoir. | ||||
| Temporal Representation: | The samples were collected in 2006, 2007 and 2008. | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Los Angeles County Department of Public Works (LACDPW) contracted Weston Solutions, Inc. to perform biological assessments. Sampling and analysis followed the protocols described in the California Stream Bioassessment Procedure (CSBP) (Harrington, 2003),and also incorporated the Southern California Index of Biotic Integrity (IBI) (Ode et al., 2005). | ||||
| QAPP Information Reference(s): | |||||