Final California 2010 Integrated Report (303(d) List/305(b) Report)

Supporting Information

Regional Board 4 - Los Angeles Region

Water Body Name:	Walnut Creek Wash (Drains from Puddingstone Res)
Water Body ID:	CAR4053100019980918112433
Water Body Type:	River & Stream


DECISION ID	7325	Region 4
Walnut Creek Wash (Drains from Puddingstone Res)

Pollutant:	Toxicity
Final Listing Decision:	Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (TMDL required list)(2006)
Revision Status	Revised
Reason for Delisting:	Applicable WQS attained; reason for recovery unspecified
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal from the section 303(d) list under section 4.6 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. LOE 4270 is a placeholder LOE for a decision made prior to 2006. LOE 25394 contains the original listing data that is not listed in LOE 4270. As such, LOE 4270 has been disassociated from the decision. Five lines of evidence are available in the administrative record to assess the pollutant. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification for removing this water segment-pollutant combination from the 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. Five out of 42 samples exhibit toxicity to Ceriodaphnia. However, four toxic results occurred in samples from 1992-93. In between 2003 and 2007, only one of 38 samples exhibited toxicity, thus significant improvements in survival and reproduction endpoints have been observed in the most recent timeframe. All of these toxicity results were measured in water samples, which are more responsive to changing pollutant loads, and in this case reflect decreasing loads. Based on the improving trend in water quality conditions and only one toxic result in the past four years, it is evident that beneficial uses are being supported. 4. Based on more recent monitoring and available monitoring data, USEPA has determined that Walnut Creek is not impaired for toxicity and a TMDL is not required. 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 be removed from the section 303(d) list because applicable water quality standards for the pollutant are not being exceeded.

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.

USEPA Action (if applicable):

Line of Evidence (LOE) for Decision ID 7325, Toxicity	Region 4
Walnut Creek Wash (Drains from Puddingstone Res)

LOE ID:

25394

Pollutant:

Toxicity

LOE Subgroup:

Toxicity

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Wetland Habitat | Wildlife Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

TOXICITY TESTING

Data Used to Assess Water Quality:

Four of four samples exhibited significant toxicity. Four samples from one site were used to test toxicity to three species: Fathead Minnow, Ceriodaphnia, and Selanastrum. The samples had no effect on Selanastrum, but had effects on the other species used in the testing. A toxicity identification evaluation (TIE) was conducted for one of the samples and data suggest that an organic constituent was responsible for toxicity.

Data Reference:

Toxicity Study of the Santa Clara River, San Gabriel River, and Calleguas Creek. Final Report. Prepared by Aquatic Toxicology Laboratory, Department of Medicine, School of Veterinary Medicine, University of California Davis.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan states at there shall be no acute or chronic toxicity in ambient waters outside mixing zones.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Toxicity was defined as a statistically significant effect in the sample exposure compared to the control using EPA-recommended hypothesis testing (parametric Dunnett's Test or non-parametric Kruskal-Wallis or Wilcoxon Two-sample Test).

Guideline Reference:

Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms, Fourth Edition. EPA 600/4-90/27.

Spatial Representation:

Samples were taken at monitoring station, SG-8, in Walnut Creek at Baldwin Park Blvd.

Temporal Representation:

Quarterly toxicity samples from were taken from June 1992 to March 1993.

Environmental Conditions:

QAPP Information:

Data was collected in compliance with the sampling and monitoring procedures detailed in University of California Davis' Work/QA Project Plan.

QAPP Information Reference(s):

Toxicity Study of the Santa Clara River, San Gabriel River, and Calleguas Creek Toxicity Work/QA Project Plan

Line of Evidence (LOE) for Decision ID 7325, Toxicity	Region 4
Walnut Creek Wash (Drains from Puddingstone Res)

LOE ID:

28004

Pollutant:

Toxicity

LOE Subgroup:

Narrative Description Data

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Wetland Habitat | Wildlife Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Based on additional monitoring and assessment of the available monitoring data, USEPA has determined that Walnut Creek is not impaired for toxicity.

Data Reference:

Letter to National Resources Defense Council, Heal the Bay, and Santa Monica Baykeeper determining no impairment for toxicity in Walnut Creek. USEPA.

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 unavailable.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 7325, Toxicity	Region 4
Walnut Creek Wash (Drains from Puddingstone Res)

LOE ID:

25396

Pollutant:

Toxicity

LOE Subgroup:

Toxicity

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Wetland Habitat | Wildlife Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

TOXICITY TESTING

Data Used to Assess Water Quality:

One of six samples exhibited significant toxicity to Ceriodaphnia. Six grab samples from two sites were used to test toxicity to two species: Fathead Minnow and Ceriodaphnia.

Data Reference:

County Sanitation Districts of Los Angeles County 2003-2006 Toxicity Testing in Walnut Creek data.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan states that there shall be no acute or chronic toxicity in ambient waters outside mixing zones.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms, Fourth Edition. EPA 600/4-90/27.

Spatial Representation:

Samples were taken at two monitoring stations, site Nos. 1 and 2, in Walnut Creek at Baldwin Park Blvd and Merced Ave.

Temporal Representation:

Monthly toxicity samples from were taken from August 2003 to October 2003.

Environmental Conditions:

QAPP Information:

Data was collected as detailed in Sanitation Districts of Los Angeles County QA/QC Memo.

QAPP Information Reference(s):

County Sanitation Districts of Los Angeles County QA/QC Memo for 2003 Toxicity testing in Walnut Creek.

Line of Evidence (LOE) for Decision ID 7325, Toxicity	Region 4
Walnut Creek Wash (Drains from Puddingstone Res)

LOE ID:

25399

Pollutant:

Toxicity

LOE Subgroup:

Toxicity

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Wetland Habitat | Wildlife Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

TOXICITY TESTING

Data Used to Assess Water Quality:

Zero out of 29 samples exhibited significant toxicity. Samples were taken from two sites and tested for toxicity to Ceriodaphnia.

Data Reference:

Technical Report 493: Wet and Dry Weather Toxicity in the San Gabriel River.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan states that there shall be no acute or chronic toxicity in ambient waters outside mixing zones.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Toxicity was defined as a statistically significant effect in the sample exposure compared to the control using EPA recommended hypothesis testing (parametric Dunnett's Test or non-parametric Fisher's Exact Test).

Guideline Reference:

Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms, Fourth Edition. EPA 600/4-90/27.

Spatial Representation:

Samples were taken from two monitoring stations, site Nos. 1 and 2, in Walnut Creek at Baldwin Park Blvd and Merced Ave.

Temporal Representation:

Monthly dry-weather samples were taken from March 2005 to August 2006 and three wet-weather samples were taken in December 2004, April 2005, and January 2006.

Environmental Conditions:

QAPP Information:

Data was collected in compliance with the sampling and monitoring procedures detailed in Southern California Coastal Water Research Project and Nautilus Environmental Quality's Assurance Project Plan.

QAPP Information Reference(s):

Evaluation of Toxicity in the San Gabriel River Watershed Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 7325, Toxicity	Region 4
Walnut Creek Wash (Drains from Puddingstone Res)

LOE ID:

28167

Pollutant:

Toxicity

LOE Subgroup:

Toxicity

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Wetland Habitat | Wildlife Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

TOXICITY TESTING

Data Used to Assess Water Quality:

Zero out of three samples exhibited significant toxicity. Samples were taken from two sites and tested for acute and chronic toxicity to Ceriodaphnia.

Data Reference:

Toxicity Monitoring in Walnut Creek 2005 to 2007.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan states that there shall be no acute or chronic toxicity in ambient waters outside mixing zones.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Toxicity was defined as a reduction of the NOEC below 100% and was considered significant if the effect on the sample exposure was greater than 25%. Chronic toxicity is further expressed as toxic units (TUc), where TUc = 100/NOEC.
The No Observable Effect Concentration (NOEC) is expressed as the maximum percent of receiving water that causes no observable effect on a test organism, as determined by the result of a critical life stage toxicity test. The NOEC is defined, in USEPA, 2002 as the the lowest concentration of toxicant to which organisms are exposed in a life-cycle or partial life-cycle (short-term) test, which causes adverse effects on the test organisms (i.e., where the values for the observed responses are statistically significantly different from the controls).

Guideline Reference:

FINAL Calleguas Creek Watershed Toxicity, Chlorpyrifos and Diazinon TMDL Technical Report. 2005. Submitted to Los Angeles Regional Water Quality Control Board. Prepared by Larry Walker Associates on behalf of the Calleguas Creek Watershed Management Plan. June 21, 2005.

Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms, Fourth Edition. EPA 600/4-90/27.

Spatial Representation:

Samples were taken from two monitoring stations, site SGLT506 and SGUT506, in Walnut Creek.

Temporal Representation:

Samples were taken on 07/25/2005, on 07/19/2006, and on 06/11/2007.

Environmental Conditions:

QAPP Information:

Data was collected in compliance with the sampling and monitoring procedures detailed in San Gabriel River Regional Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

San Gabriel River Regional Monitoring Program Quality Assurance Project Plan. San Gabriel River Regional Monitoring Program.


DECISION ID	9490	Region 4
Walnut Creek Wash (Drains from Puddingstone Res)

Pollutant:	Copper, Dissolved
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 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. 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 against placing this water segment-pollutant combination on the 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. One of six samples exceeded the CTR freshwater criteria (chronic) 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:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):

Line of Evidence (LOE) for Decision ID 9490, Copper, Dissolved	Region 4
Walnut Creek Wash (Drains from Puddingstone Res)

LOE ID:

9025

Pollutant:

Copper, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Preservation of Rare & Endangered Species | Wildlife Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Los Angeles County Department of Public Works monitoring reports (2006-2007), submitted electronically

Data Reference:

2006-2007 Monitoring Data (MS4 Data) for Tributaries of the San Gabriel River Watershed- CI 6948 for order no. 01-182 NPDES No. CAS004001 Municipal Storm Water and Urban Runoff Discharges within the County of Los Angeles, and the Incorporated Cities therein, Except the City of Long Beach.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

CTR Dissolved Copper Criterion for continuous concentration (CCC) and maximum concentration (CMC) in water for the protection of aquatic life is expressed as a function of the total hardness of the water body. The aquatic life criteria will vary depending of total hardness reported at the sampling site. The CMC is the highest concentration of a pollutant to which aquatic life can be exposed for a short period of time without deleterious effects and the CCC is the highest concentration to which aquatic life can be exposed for an extended period of time (four days) without deleterious effects. This criterion is linked and applicable for the protection of aquatic life Beneficial Uses.

Objective/Criterion Reference:

Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station: TS13, at the confluence of Walnut Creek and Big Dalton Wash

Temporal Representation:

Composite samples, approximately six per year (four wet-weather events and two dry-weather events), from October 2006 through April 2007.

Environmental Conditions:

QAPP Information:

Data collected for compliance with NPDES Permit No. CAS004001 Monitoring and Reporting Program.

QAPP Information Reference(s):

Monitoring and Reporting Program - CI 6948 for order no. 01-182 NPDES No. CAS004001 Municipal Storm Water and Urban Runoff Discharges within the County of Los Angeles, and the incorporated cities, except the City of Long Beach


DECISION ID	9491	Region 4
Walnut Creek Wash (Drains from Puddingstone Res)

Pollutant:	Lead
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 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. 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 against placing this water segment-pollutant combination on the 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. One of six samples exceeded the California Toxics Rule Criterion Continuous Concentration for Lead 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:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):

Line of Evidence (LOE) for Decision ID 9491, Lead	Region 4
Walnut Creek Wash (Drains from Puddingstone Res)

LOE ID:

9027

Pollutant:

Lead

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Preservation of Rare & Endangered Species | Wildlife Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Los Angeles County Department of Public Works monitoring reports (2006-2007), submitted electronically

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station: TS13, at the confluence of Walnut Creek and Big Dalton Wash

Temporal Representation:

Composite samples were taken approximately six per year (four wet-weather events and two dry-weather events), from October 2006 through April 2007.

Environmental Conditions:

QAPP Information:

Data was collected in compliance with the sampling and monitoring procedures detailed in County of Los Angeles MS4 Permit (NPDES No. CAS004001) Monitoring and Reporting Program.

QAPP Information Reference(s):


DECISION ID	17216	Region 4
Walnut Creek Wash (Drains from Puddingstone Res)

Pollutant:	Benthic-Macroinvertebrate Bioassessments
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Sources:	Source Unknown
Expected TMDL Completion Date:	2012
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Regional Board Conclusion: This pollutant is being considered for the section 303(d) list 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 is available in the administrative record to assess this pollutant. Benthic macroinvertebrates as measured by Southern California IBI (index of biological integrity) in Walnut Creek were very poor in October of 2003 and very poor in October of 2004 indicating impairment of benthic community structure. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification to place the water segment in category 4C combinaon the 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. There is at least one bioassessment sample (Index of Biological Integrity score) to satisfy Section 3.9 4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are met. State Board Review and Conclusion: State Water Board staff used a situation-specific weight of evidence approach to evaluate the Los Angeles Water Board benthic macroinvertebratebioassessment listing. State Water Board staff determined that it is necessary to include these listings because additional data analyses and multiple line of evidence show that benthic macroinvertebrate populations are impacted by a wide range of stressors. Using this approach staff followed a three-step process for evaluation of all available water quality data including the chemistry, bioassessment data, and toxicity. In the first step, staff reviewed the Los Angeles Water Board data evaluation for bioassessment listing. In the second step, staff reviewed all other available bioassessment data because State Water Board staff learned that some data had not been considered for this listing decision by the Regional Water Board. In step 3 staff reviewed the chemistry water quality data available for Indicator bacteria, lead, zinc, copper, mercury, and oil and grease to determine the water quality condition in this water body segment. In step 1 and 2, State Water Board staff evaluated the bioassessment data using the Southern California index of biological integrity (IBI). Staff reviewed the line of evidence prepared by the Los Angeles Water Board and additional bioassessment data. Benthic macroinvertebrate as measured by Southern California IBI in Walnut Creek were poor in 2003 and 2004 indicating impairment of benthic community structure. In step 3, the chemistry data for indicator bacteria, lead, zinc, copper, mercury, and oil and grease were evaluated by State Water Board staff. Data for toxicity and pH were evaluated in a previous listing cycle. pH showed impairment to the warm freshwater habitat and it resulted in listing this water body in 1996. In this step State Water Board staff evaluated the most recent available data for indicator bacteria, lead, zinc, copper, mercury, and oil and grease. The data for fecal coliform show that 5 of 6 samples exceeded the water quality objective. The data for lead show that 1 of 7 samples exceeded the water quality objective. The data for zinc show that 1 of 7 samples exceeded the water quality objective. The data for copper show that 1 of 7 samples exceeded the water quality objective. The data for mercury show that 2 of 7 samples exceeded the water quality objective. The data for oil and grease show that 1 of 6 samples exceeded the water quality objective. The weight of evidence of the data and information indicate that the beneficial use of the water is not supported. The water quality chemistry and bioassessment data provide a substantial basis that benthic macroinvertebrate populations are impacted by a wide range of anthropogenic stressors. Based on the available data and information, staff recommend to list for benthic macroinvertebrate-bioassessment.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be added to the section 303(d) list because applicable water quality standards are not being attained.

State Board Review of Regional Board Conclusion and Recommendation:	The water quality chemistry and bioassessment data provide a substantial basis that benthic macroinvertebrate populations are impacted by a wide range of anthropogenic stressors. Based on the available data and information, staff recommend to list for benthic macroinvertebrate-bioassessment.

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):	USEPA approved the listing of this water body as a water quality limited segment requiring a TMDL for this pollutant.

Line of Evidence (LOE) for Decision ID 17216, Benthic-Macroinvertebrate Bioassessments	Region 4
Walnut Creek Wash (Drains from Puddingstone Res)

LOE ID:

30227

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Cold Freshwater Habitat | Preservation of Rare & Endangered Species | Wetland Habitat | Wildlife Habitat

Number of Samples:

Number of Exceedances:

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 (7 in 2003 and 6 in 2004).

Data Reference:

Los Angeles County 1994-2005 Integrated Receiving Water Impacts Report. Section 4, San Gabriel River Watershed Management Area, pp4.1 - 4.36.

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:

A Quantitative Tool for Assessing the Integrity of Southern Coastal California Streams. Appendix 7-B Environmental Management Vol. 35, No. 4, pp. 493-504.

Los Angeles County 1994-2005 Integrated Receiving Water Impacts Report. Section 3, Methods, pp3.1 - 3.28

Los Angeles County 1994-2005 Integrated Receiving Water Impacts Report. Section 4, San Gabriel River Watershed Management Area, pp4.1 - 4.36.

Spatial Representation:

One site in Walnut Creek was sampled, downstream of N. Baldwin Park Blvd, at N 34º 03.674 W 117º 59.847.

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):

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

Los Angeles County 1994-2005 Integrated Receiving Water Impacts Report. Section 3, Methods, pp3.1 - 3.28


DECISION ID	16193	Region 4
Walnut Creek Wash (Drains from Puddingstone Res)

Pollutant:	Indicator Bacteria
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Sources:	Source Unknown
Expected TMDL Completion Date:	2021
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the section 303(d) list under section 3.3 of the Listing Policy. Under section 3.3 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 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. Five of six samples exceed the Basin Plan single single sample water quality objectives for indicator bacteria in fresh water 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 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:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):	USEPA approved the listing of this water body as a water quality limited segment requiring a TMDL for this pollutant.

Line of Evidence (LOE) for Decision ID 16193, Indicator Bacteria	Region 4
Walnut Creek Wash (Drains from Puddingstone Res)

LOE ID:

26867

Pollutant:

Indicator Bacteria

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

Other Agencies/Organizations provided monitoring data

Data Used to Assess Water Quality:

Five of six samples exceeded the Basin Plan single sample water quality objectives for indicator bacteria in fresh water and one of one sample exceeded the Basin Plan geometric mean water quality objective. Water quality samples were taken and analyzed for indicator bacteria in accordance with the Municipal Separate Storm Sewer System (MS4) permit monitoring and testing parameters.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan bacteria objectives state that to protect water contact recreation in fresh waters individual samples shall not exceed the following limits: fecal coliform density shall not exceed 400/100 ml; and E. coli density shall not exceed 235/100 ml. The bacteria objectives also establish that the geometric means of individual samples shall not exceed the following limits: the fecal coliform density shall not exceed 200/100 ml; and the E. coli density shall not exceed 126/100 ml, as a geometric mean. The bacteria objectives are found in Attachment A of Regional Board Resolution No. 2001-018.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The Los Angeles County Department of Public Works conducted sampling at the mass emmission monitoring station TS13 located at the confluence of Walnut Creek and Big Dalton Wash.

Temporal Representation:

Grab samples were taken approximately six per year (four wet-weather events and two dry-weather events), from October 2006 through April 2007.

Environmental Conditions:

QAPP Information:

Data was collected in compliance with the sampling and monitoring procedures detailed in County of Los Angeles MS4 Permit (NPDES No. CAS004001) Monitoring and Reporting Program.

QAPP Information Reference(s):


DECISION ID	7323	Region 4
Walnut Creek Wash (Drains from Puddingstone Res)

Pollutant:	pH
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (TMDL required list)(2006)
Revision Status	Original
Sources:	Nonpoint Source \| Point Source
Expected TMDL Completion Date:	2007
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	303(d) listing decisions made prior to 2006 were not held in an assessment database. The Regional Boards will update this decision when new data and information become available and are assessed.

Regional Board Decision Recommendation:	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.

USEPA Action (if applicable):	USEPA approved the listing of this water body as a water quality limited segment requiring a TMDL for this pollutant.

Line of Evidence (LOE) for Decision ID 7323, pH	Region 4
Walnut Creek Wash (Drains from Puddingstone Res)

LOE ID:

4269

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

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):