| Water Body Name: | Del Rey Lagoon |
| Water Body ID: | CAS4047000020210326048829 |
| Water Body Type: | Saline Lake |
DECISION ID |
150289 |
Region 4 |
Del Rey Lagoon |
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| Pollutant: | Indicator Bacteria |
| Final Listing Decision: | List on 303(d) list (being addressed by USEPA approved TMDL) |
| Last Listing Cycle's Final Listing Decision: | New Decision |
| Revision Status | Revised |
| Sources: | See TMDL documentation |
| TMDL Name: | Ballona Creek Coliform (49) |
| TMDL Project Code: | 393 |
| Date TMDL Approved by USEPA: | 05/08/2008 |
| 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 3.3 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are 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. 20 of 28 samples exceed the geometric mean for Enterococcus and 13 of 46 samples exceeded the statistical threshold value for Enterococcus 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: | 303164 | ||||
| Pollutant: | Enterococcus | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | STV | ||||
| Beneficial Use: | Water Contact Recreation | ||||
| Number of Samples: | 46 | ||||
| Number of Exceedances: | 13 | ||||
| Data and Information Type: | PATHOGEN MONITORING | ||||
| Data Used to Assess Water Quality: | Water Board staff assessed LA County MS4 data for Del Rey Lagoon to determine beneficial use support and the results are as follows: 13 of the 46 samples exceeded the Statistical Threshold Value (STV) water quality threshold for Enterococcus. The STV is based on a 10% exceedance rate that is calculated monthly. | ||||
| Data Reference: | WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4. | ||||
| SWAMP Data: | Non-SWAMP | ||||
| Water Quality Objective/Criterion: | The bacteria water quality objective to protect the REC-1 beneficial use where the salinity is 1 ppth or higher 95 percent or more of the time applies a Statistical Threshold Value to enterococcus of 110 cfu/100 mL, not to be exceeded by more than 10 percent of samples collected within in a calendar month. (ISWEBE 2018) | ||||
| Objective/Criterion Reference: | Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy | ||||
| Evaluation Guideline: | |||||
| Guideline Reference: | |||||
| Spatial Representation: | The samples were collected at 1 monitoring site(s), station(s): DRL-BCE (DRL-BCE). | ||||
| Temporal Representation: | The samples were collected between the days of 2015-03-20 and 2019-12-26 . | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Municipal Separate Storm Sewer System (MS4) | ||||
| QAPP Information Reference(s): | Municipal Separate Storm Sewer System (MS4) | ||||
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| LOE ID: | 303051 | ||||
| Pollutant: | Enterococcus | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | GeoMean | ||||
| Beneficial Use: | Water Contact Recreation | ||||
| Number of Samples: | 28 | ||||
| Number of Exceedances: | 20 | ||||
| Data and Information Type: | PATHOGEN MONITORING | ||||
| Data Used to Assess Water Quality: | Water Board staff assessed LA County MS4 data for Del Rey Lagoon to determine beneficial use support and the results are as follows: 20 of the 28 samples exceeded the geomean water quality threshold for Enterococcus. This is a six week rolling geomean that is calculated weekly. | ||||
| Data Reference: | WQ data from the MS4 database assembled for the 2024 Integrated Report in Region 4. | ||||
| SWAMP Data: | Non-SWAMP | ||||
| Water Quality Objective/Criterion: | The bacteria water quality objective to protect the REC-1 beneficial use where the salinity is 1 ppth or higher 95 percent or more of the time applies a six-week rolling geomean to enterococcus, not to exceed 30 cfu/100mL. (ISWEBE 2018) | ||||
| Objective/Criterion Reference: | Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy | ||||
| Evaluation Guideline: | |||||
| Guideline Reference: | |||||
| Spatial Representation: | The samples were collected at 1 monitoring site(s), station(s): DRL-BCE (DRL-BCE). | ||||
| Temporal Representation: | The samples were collected between the days of 2015-03-20 and 2019-12-26 . | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Municipal Separate Storm Sewer System (MS4) | ||||
| QAPP Information Reference(s): | Municipal Separate Storm Sewer System (MS4) | ||||