| Water Body Name: | Arroyo Seco Reach 1 (LA River to West Holly Ave.) |
| Water Body ID: | CAR4051501019990202132906 |
| Water Body Type: | River & Stream |
DECISION ID |
150276 |
Region 4 |
Arroyo Seco Reach 1 (LA River to West Holly Ave.) |
||
| Pollutant: | Indicator Bacteria |
| Final Listing Decision: | Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL) |
| Last Listing Cycle's Final Listing Decision: | List on 303(d) list (being addressed by USEPA approved TMDL)(2018) |
| Revision Status | Revised |
| Sources: | A Source Unknown |
| TMDL Name: | Los Angeles River Pathogens (15) |
| TMDL Project Code: | 238 |
| Date TMDL Approved by USEPA: | 03/23/2012 |
| Impairment from Pollutant or Pollution: | Pollutant |
| Regional Board Conclusion: | This pollutant is being considered for removal on the CWA section 303(d) List under sections 2.2, 4.3 and 4.11 of the Listing Policy. Under section 4.3 of the Policy, a minimum of one line of evidence is needed to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Because a statistically sufficient number of geomean samples were not available, attainment of the bacteria objective was determined based only on the STV per the situation-specific weight of evidence approach outlined in Sections 4.11 of the Listing Policy. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the CWA section 303(d) List. There is sufficient justification to place it in the Being Addressed portion of the CWA 303(d) List because a TMDL has been completed and approved by RWQCB and USEPA, and is expected to result in attainment of the standard. 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. 31 of 36 samples exceeded the statistical threshold value for E. coli and these exceed the allowable frequency listed in Table 4.2 of the Listing Policy. 4. The The Los Angeles River Bacteria TMDL was approved by USEPA on 03/23/2012. 5. Pursuant to section 4.11 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 removed from the section 303(d) list because applicable water quality standards for the pollutant are being exceeded. |
| State Board Review of Regional Board Conclusion and Recommendation: | |
| State Board Decision Recommendation: | |
|
|||||
| LOE ID: | 4027 | ||||
| Pollutant: | Coliform Bacteria | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | Not Recorded | ||||
| Beneficial Use: | Water Contact Recreation | ||||
| Number of Samples: | 0 | ||||
| Number of Exceedances: | 0 | ||||
| Data and Information Type: | Not Specified | ||||
| Data Used to Assess Water Quality: | Unspecified--This LOE is a placeholder to support a 303(d) listing decision made prior to 2006. | ||||
| Data Reference: | Placeholder reference pre-2006 303(d) | ||||
| SWAMP Data: | Non-SWAMP | ||||
| Water Quality Objective/Criterion: | Unspecified | ||||
| Objective/Criterion Reference: | Placeholder reference pre-2006 303(d) | ||||
| Evaluation Guideline: | Unspecified | ||||
| Guideline Reference: | Placeholder reference pre-2006 303(d) | ||||
| Spatial Representation: | Unspecified | ||||
| Temporal Representation: | Unspecified | ||||
| Environmental Conditions: | Unspecified | ||||
| QAPP Information: | Unspecified | ||||
| QAPP Information Reference(s): | |||||
|
|||||
| LOE ID: | 303140 | ||||
| Pollutant: | Escherichia coli (E. coli) | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | STV | ||||
| Beneficial Use: | Water Contact Recreation | ||||
| Number of Samples: | 36 | ||||
| Number of Exceedances: | 31 | ||||
| Data and Information Type: | PATHOGEN MONITORING | ||||
| Data Used to Assess Water Quality: | Water Board staff assessed LA County MS4 data for Arroyo Seco Reach 1 (LA River to West Holly Ave.) to determine beneficial use support and the results are as follows: 31 of the 36 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. 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 less than 1 parts per thousand 95 percent or more of the time applies a statistical threshold value to E. coli of 320 cfu/100 mL, not to be exceeded by more than 10 percent of samples within 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): AS_SAN (Arroyo Seco (San Fernando Rd)). | ||||
| Temporal Representation: | The samples were collected between the days of 2015-11-18 and 2019-12-18 . | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Municipal Separate Storm Sewer System (MS4) | ||||
| QAPP Information Reference(s): | Municipal Separate Storm Sewer System (MS4) | ||||
DECISION ID |
79690 |
Region 4 |
Arroyo Seco Reach 1 (LA River to West Holly Ave.) |
||
| Pollutant: | Benthic Community Effects |
| Final Listing Decision: | Delist from 303(d) list (TMDL required list) |
| Last Listing Cycle's Final Listing Decision: | Delist from 303(d) list (TMDL required list)(2016) |
| Revision Status | Original |
| Reason for Delisting: | Flaws in original listing |
| Impairment from Pollutant or Pollution: | Pollutant |
| Regional Board Conclusion: | In 2010 this pollutant was listed under section 3.9 of the Listing Policy. Under section 3.9, waters are listed when a bioassessment shows diminished numbers of species or other metrics (compared to a reference site) and it is associated with another pollutant. One line of evidence was available in the administrative record to assess this pollutant. Benthic macroinvertebrates as measured by Southern California IBI (Index of Biological Integrity) in Arroyo Seco Reach 1 were very poor 2003 to 2008.
Based on the readily available data and information, the weight of evidence indicated that there is sufficient justification to place the water segment-pollutant combination in Category 3 of the section 303(d) list in the Water Quality Limited Segments category. This decision has been changed to delist as there is insufficient information to determine an associated pollutant per Section 3.9 of the Listing Policy. More data is needed to determine if water quality 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 following changes to the decision:
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. However, more sampling should be done as the information available indicates impairment may be probable. |
|
|||||
| LOE ID: | 30223 | ||||
| Pollutant: | Benthic-Macroinvertebrate Bioassessments | ||||
| LOE Subgroup: | Population/Community Degradation | ||||
| Matrix: | Water | ||||
| Fraction: | None | ||||
| Beneficial Use: | Non-Contact Recreation | ||||
| Number of Samples: | 0 | ||||
| Number of Exceedances: | 0 | ||||
| Data and Information Type: | Benthic macroinvertebrate surveys | ||||
| Data Used to Assess Water Quality: | The IBI scores at this site ranked in the ¿very poor¿ range (11 in 2003 and 9 in 2004). | ||||
| Data Reference: | Los Angeles County 1994-2005 Integrated Receiving Water Impacts Report. Section 5, Los Angeles River Watershed Management Area, pp5.1 - 5.40 | ||||
| SWAMP Data: | Non-SWAMP | ||||
| Water Quality Objective/Criterion: | Los Angeles RWQCB Basin Plan Objectives for Toxicity which states ¿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, analyses of species diversity, population density, growth anomalies, bioassays of appropriate duration or other appropraite methods as specified by the State or Regional Board.¿ | ||||
| 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 according to very good (80-56), good (41-55), fair (27-40), poor (14-26) and very poor (0-13) habitat conditions. Sites with scores below 26 are considered to have impaired conditions. | ||||
| Guideline Reference: | Los Angeles County 1994-2005 Integrated Receiving Water Impacts Report. Section 3, Methods, pp3.1 - 3.28 | ||||
| Guideline Reference: | Los Angeles County 1994-2005 Integrated Receiving Water Impacts Report. Section 5, Los Angeles River Watershed Management Area, pp5.1 - 5.40 | ||||
| Guideline Reference: | A Quantitative Tool for Assessing the Integrity of Southern Coastal California Streams. Appendix 7-B Environmental Management Vol. 35, No. 4, pp. 493-504. | ||||
| Spatial Representation: | One site in the Arroyo Seco was sampled, Arroyo Seco and I-134, at N 34º 08.686¿ W 118º 09.987¿ | ||||
| Temporal Representation: | Sites were sampled in October of 2003 and October of 2004. | ||||
| Environmental Conditions: | Benthic macroinvertebrate populations and IBI scores may also be affected by a wide range of anthropogenic stressors. | ||||
| QAPP Information: | Data was collected in compliance with California Stream Bioassessment Procedure. | ||||
| QAPP Information Reference(s): | Los Angeles County 1994-2005 Integrated Receiving Water Impacts Report. Section 3, Methods, pp3.1 - 3.28 | ||||
| QAPP Information Reference(s): | California Stream Bioassessment Procedure (Protocol Brief for Biological and Physical/Habitat Assessment in Wadeable Streams) California Department of Fish and Game Water Pollution Control Laboratory Aquatic Bioassessment Laboratory Revision Date - December, 2003 | ||||
|
|||||
| LOE ID: | 96151 | ||||
| Pollutant: | Benthic-Macroinvertebrate Bioassessments | ||||
| LOE Subgroup: | Population/Community Degradation | ||||
| Matrix: | Water | ||||
| Fraction: | None | ||||
| 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 Arroyo Seco Reach 1 over three years. Three of the three samples collected had IBI scores below 40. The scores were 17 (2006), 11 (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. | ||||
| 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: | A Quantitative Tool for Assessing the Integrity of Southern Coastal California Streams. Environmental Management. Volume 35, number 1 (2005): pp. 1-13 | ||||
| Spatial Representation: | The samples were collected from Arroyo Seco downstream from I-134, station 7. | ||||
| Temporal Representation: | The samples were collected in 2006, 2007 and 2008. | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Qaulity assurance is good. 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): | |||||
|
|||||
| LOE ID: | 82895 | ||||
| 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: | One sample was collected from Arroyo Seco Reach 1. The one sample collected had an IBI score below 40. The score was 2 (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. | ||||
| 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: | A Quantitative Tool for Assessing the Integrity of Southern Coastal California Streams. Environmental Management. Volume 35, number 1 (2005): pp. 1-13 | ||||
| Spatial Representation: | The sample was collected from Arroyo Seco at Los Angeles River, station LALT501. | ||||
| Temporal Representation: | The sample was collected in 2008. | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Qaulity assurance is good. 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): | |||||
DECISION ID |
68532 |
Region 4 |
Arroyo Seco Reach 1 (LA River to West Holly Ave.) |
||
| Pollutant: | Excess Algal Growth |
| Final Listing Decision: | Delist from 303(d) list (TMDL required list) |
| Last Listing Cycle's Final Listing Decision: | Delist from 303(d) list (TMDL required list)(2016) |
| Revision Status | Original |
| Reason for Delisting: | Flaws in original listing |
| Impairment from Pollutant or Pollution: | Pollutant |
| Regional Board Conclusion: | This condition is being considered for listing under section 2.2 of the Listing Policy. Under this section of the Policy, a minimum of two lines of evidence is needed to assess listing status.
The Los Angeles River Nitrogen TMDL was approved by RWQCB on August 19, 2003 and subsequently approved by USEPA on March 18, 2004. This TMDL will address this water body condition. Qualitative information on excess algal growth alone is not sufficient to support placement on the section 303(d) list (Listing Policy section 3.7). 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 in the Water Quality Limited Segments Being Addressed portion of the section 303(d) list. |
| Regional Board Decision Recommendation: | This is a decision previously approved by the State Water Resources Control Board and the USEPA. No new data were assessed by the Regional Board for the current. The decision has not changed. |
| 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. |
|
|||||
| LOE ID: | 2486 | ||||
| Pollutant: | Excess Algal Growth | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | Not Recorded | ||||
| Beneficial Use: | Warm Freshwater Habitat | ||||
| Number of Samples: | 0 | ||||
| Number of Exceedances: | 0 | ||||
| Data and Information Type: | Not Specified | ||||
| Data Used to Assess Water Quality: | Unspecified--This LOE is a placeholder to support a 303(d) listing decision made prior to 2006. | ||||
| Data Reference: | Placeholder reference 2006 303(d) | ||||
| SWAMP Data: | Non-SWAMP | ||||
| Water Quality Objective/Criterion: | |||||
| Objective/Criterion Reference: | |||||
| Evaluation Guideline: | |||||
| Guideline Reference: | |||||
| Spatial Representation: | |||||
| Temporal Representation: | |||||
| Environmental Conditions: | |||||
| QAPP Information: | QA Info Missing | ||||
| QAPP Information Reference(s): | |||||
DECISION ID |
75547 |
Region 4 |
Arroyo Seco Reach 1 (LA River to West Holly Ave.) |
||
| Pollutant: | Trash |
| Final Listing Decision: | List on 303(d) list (being addressed by USEPA approved TMDL) |
| Last Listing Cycle's Final Listing Decision: | List on 303(d) list (being addressed by USEPA approved TMDL)(2016) |
| Revision Status | Original |
| Sources: | Nonpoint Source | Surface Runoff | Urban Runoff/Storm Sewers |
| TMDL Name: | Los Angeles River Trash (12) |
| TMDL Project Code: | 365 |
| Date TMDL Approved by USEPA: | 07/24/2008 |
| Impairment from Pollutant or Pollution: | Pollutant |
| Regional Board Conclusion: | This pollutant is being considered for removal on the section 303(d) list under sections 2.2 of the Listing Policy. Under 2.2 of the Policy, a minimum of one line of evidence is needed 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 against removing this water segment-pollutant combination from the section 303(d) list. There is sufficient justification to place it in the Being Addressed portion of the 303(d) list because a TMDL has been completed and adopted by the Los Angeles RWQCB and approved by USEPA, and is expected to result in attainment of the standard. |
| Regional Board Decision Recommendation: | This is a decision previously approved by the State Water Resources Control Board and the USEPA. No new data were assessed by the Regional Board for the current. The decision has not changed. |
| 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. |
|
|||||
| LOE ID: | 4028 | ||||
| Pollutant: | Trash | ||||
| LOE Subgroup: | Visual | ||||
| Matrix: | Not Specified | ||||
| Fraction: | Not Recorded | ||||
| Beneficial Use: | Non-Contact Recreation | ||||
| Number of Samples: | 0 | ||||
| Number of Exceedances: | 0 | ||||
| Data and Information Type: | Not Specified | ||||
| Data Used to Assess Water Quality: | Unspecified--This LOE is a placeholder to support a 303(d) listing decision made prior to 2006. | ||||
| Data Reference: | Placeholder reference pre-2006 303(d) | ||||
| SWAMP Data: | Non-SWAMP | ||||
| Water Quality Objective/Criterion: | Unspecified | ||||
| Objective/Criterion Reference: | Placeholder reference pre-2006 303(d) | ||||
| Evaluation Guideline: | Unspecified | ||||
| Guideline Reference: | Placeholder reference pre-2006 303(d) | ||||
| Spatial Representation: | Unspecified | ||||
| Temporal Representation: | Unspecified | ||||
| Environmental Conditions: | Unspecified | ||||
| QAPP Information: | Unspecified | ||||
| QAPP Information Reference(s): | |||||
|
|||||
| LOE ID: | 28085 | ||||
| Pollutant: | Trash | ||||
| LOE Subgroup: | Narrative Description Data | ||||
| Matrix: | Not Specified | ||||
| Fraction: | None | ||||
| Beneficial Use: | Non-Contact Recreation | ||||
| Number of Samples: | 0 | ||||
| Number of Exceedances: | 0 | ||||
| Data and Information Type: | Not Specified | ||||
| Data Used to Assess Water Quality: | A TMDL has been approved for this water segment-pollutant combination. The Trash TMDL for the Los Angeles River Watershed was adopted by the Los Angeles RWQCB on August 09, 2007 and subsequently approved by USEPA. The TMDL was been integrated into the Basin Plan as Attachment A of Regional Board Resolution No. 2007-012. | ||||
| Data Reference: | Water Quality Control Plan Los Angeles Region R4 Basin Plan | ||||
| SWAMP Data: | Non-SWAMP | ||||
| Water Quality Objective/Criterion: | |||||
| Objective/Criterion Reference: | |||||
| Evaluation Guideline: | |||||
| Guideline Reference: | |||||
| Spatial Representation: | |||||
| Temporal Representation: | |||||
| Environmental Conditions: | |||||
| QAPP Information: | QA information unavailable. | ||||
| QAPP Information Reference(s): | |||||