Draft California 2020 Integrated Report (303(d) List/305(b) Report)

Supporting Information

Regional Board 8 - Santa Ana Region

Water Body Name:	East Twin Creek
Water Body ID:	CAR8015200020110830095105
Water Body Type:	River & Stream


DECISION ID	96739	Region 8
East Twin Creek

Pollutant:	Indicator Bacteria
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:	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. Four (4) lines of evidence are available in the administrative record to assess this pollutant. Two (2) of 37 samples exceed the E. coli Geomean Objective. 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. 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. Two (2) of the 37 samples exceed the E. coli Geomean, and this does not exceed the frequency listed in table 3.2 4. The line of evidence based on the single sample maximum was not included in the Final Use Rating as the Region 8 Basin Plan states that where a representative geometric mean can be calculated, single sample maximum values shall not be used for assessment (page 4-17, footnote 3). 5. 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.

Line of Evidence (LOE) for Decision ID 96739, Indicator Bacteria	Region 8
East Twin Creek

LOE ID:

81463

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Two of the 37 samples exceeded the E. coli evaluation guideline fpr geometric mean.

Data Reference:

Data for Various Pollutants in Region 8, 2008-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The concentrations of toxic pollutants in the water column, sediments or biota shall not adversely affect beneficial uses. Santa Ana Region basin Plan.

Objective/Criterion Reference:

Water Quality Control Plan, Santa Ana River Basin

Evaluation Guideline:

Geomean: The E. coli concentration for geometric mean shall not exceed more than 126/100ml. USEPA Ambient Water Quality Criteria for Bacteria -1986.

Guideline Reference:

Ambient Water Quality Criteria for Bacteria - 1986. EPA440/5-84-002

Spatial Representation:

The samples were collected from East Twin Creek WC1 and WC3.

Temporal Representation:

The samples were collected once a week from July 2008 to November 2009.

Environmental Conditions:

QAPP Information:

Data was collected under the Qality Assurance Project Plan for the Upper Santa Ana River Watershed Water Quality Assessment Project.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 96739, Indicator Bacteria	Region 8
East Twin Creek

LOE ID:

81462

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Twelve of the 72 samples exceeded the E. coli evaluation guideline.

Data Reference:

Data for Various Pollutants in Region 8, 2008-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The concentrations of toxic pollutants in the water column, sediments or biota shall not adversely affect beneficial uses. Santa Ana Region basin Plan.

Objective/Criterion Reference:

Water Quality Control Plan, Santa Ana River Basin

Evaluation Guideline:

The single sample E. coli concentration shall not exceed more than 235/100ml. USEPA Ambient Water Quality Criteria for Bacteria -1986.

Guideline Reference:

Ambient Water Quality Criteria for Bacteria - 1986. EPA440/5-84-002

Spatial Representation:

The samples were collected from East Twin Creek WC1 and WC3.

Temporal Representation:

The samples were collected once a week from July 2008 to November 2009.

Environmental Conditions:

QAPP Information:

Data was collected under the Qality Assurance Project Plan for the Upper Santa Ana River Watershed Water Quality Assessment Project.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 96739, Indicator Bacteria	Region 8
East Twin Creek

LOE ID:

81465

Pollutant:

Total Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Thirty-six of the 37 samples exceeded the total coliform evaluation guideline for geometric mean.

Data Reference:

Data for Various Pollutants in Region 8, 2008-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The concentrations of toxic pollutants in the water column, sediments or biota shall not adversely affect beneficial uses. Santa Ana Region basin Plan.

Objective/Criterion Reference:

Water Quality Control Plan, Santa Ana River Basin

Evaluation Guideline:

Geomean: The total coliform concentration for geometric mean shall not exceed more than 1000/100ml. Guidance for Fresh Water Beaches (CDPH 2011).

Guideline Reference:

Draft Guidance for Fresh Water Beaches. Last Update: May 8, 2006. Initial Draft: November 1997. California Department of Public Health.

Spatial Representation:

The samples were collected from East Twin Creek WC1 and WC3.

Temporal Representation:

The samples were collected once a week from July 2008 to November 2009.

Environmental Conditions:

QAPP Information:

Data was collected under the Qality Assurance Project Plan for the Upper Santa Ana River Watershed Water Quality Assessment Project.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 96739, Indicator Bacteria	Region 8
East Twin Creek

LOE ID:

81464

Pollutant:

Total Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Thirty-one of the 72 samples exceeded the total coliform evaluation guideline.

Data Reference:

Data for Various Pollutants in Region 8, 2008-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The concentrations of toxic pollutants in the water column, sediments or biota shall not adversely affect beneficial uses. Santa Ana Region basin Plan.

Objective/Criterion Reference:

Water Quality Control Plan, Santa Ana River Basin

Evaluation Guideline:

The single sample total coliform concentration shall not exceed more than 10,000/100ml. Guidance for Fresh Water Beaches (CDPH 2011).

Guideline Reference:

Draft Guidance for Fresh Water Beaches. Last Update: May 8, 2006. Initial Draft: November 1997. California Department of Public Health.

Spatial Representation:

The samples were collected from East Twin Creek.

Temporal Representation:

The samples were collected once a week from July 2008 to November 2009.

Environmental Conditions:

QAPP Information:

Data was collected under the Qality Assurance Project Plan for the Upper Santa Ana River Watershed Water Quality Assessment Project.

QAPP Information Reference(s):