Draft 2008 California 303(d)/305(b) Integrated Report

Supporting Information

Regional Board 2 - San Francisco Bay Region

Water Body Name: San Pedro Creek
Water Body ID: CAR2022101120010905120841
Water Body Type: River & Stream
 
DECISION ID
4078
 
Pollutant: Coliform Bacteria
Final Listing Decision: Do Not Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not Delist from 303(d) list (TMDL required list)(2006)
Revision Status Original
Sources: Nonpoint Source | Urban Runoff/Storm Sewers
Expected TMDL Completion Date: 2010
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: This pollutant is being considered for removal from the section 303(d) list under section 4.3 of the Listing Policy. Under section 4.3 a single line of evidence is necessary to assess delisting status.

One line of evidence is available in the administrative record to assess this pollutant. A large number of samples exceed the water quality objective.

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.

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. Most of the samples exceeded the total and fecal water quality objectives and this exceeds the allowable frequency listed in Table 4.2 of the Listing Policy.
4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are met.
 
RWQCB Board Decision / Staff Recommendation: No new data were assessed for 2008. The Regional Board will update this decision when new data and information become available and are assessed.
 
SWRCB Board Decision / Staff Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be removed from on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 4078
 
LOE ID: 1769
 
Pollutant: Coliform Bacteria
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 6
Number of Exceedances: 6
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Ninety-nine samples for total coliform, 6 samples for fecal coliform, for Basin Plan data set. 41 samples for total coliform, 23 samples for fecal coliform for Ocean Plan data set. Basin Plan objectives violated in 13% samples for total coliform, 98% samples for total coliform median, and 100% violated for samples of fecal coliform geomean and fecal coliform in dry weather months (SWRCB, 2003).

Ocean Plan objectives violated in 90% of the samples for total coliform, 96% of samples for fecal coliform geomean, and 100% fecal coliform in dry weather months. E. coli data show 67% samples for total coliform maximum designated beach violated the Basin Plan Objectives. Basin Plan objectives violated in 63% samples for E. coli maximum moderately-used beach, violated in 57% samples for maximum lightly-used beach and violated in 57% samples for maximum infrequently-used beach, in dry weather months.
Data Reference: Placeholder reference 2006 303(d)
 
Water Quality Objective/Criterion: Basin Plan objectives (SFBRWQCB, 1995)
Fecal coliform
Log mean <200 MPN/100ml 90th percentile <400 MPN/100ml
Total coliform
Log mean <240 MPN/100ml
90th percentile >10,000 MPN/100ml

Ocean Plan Objectives (SWRCB, 2001)
Samples of water from each sampling station shall have a density of total coliform organisms less than 1,000 per 100 ml (10 per ml); provided that not more than 20 percent of the samples at any sampling station, in any 30-day period, may exceed 1,000 per 100 ml (10 per ml), and provided further that no single sample when verified by a repeat sample taken within 48 hours shall exceed 10,000 per 100 ml (100 per ml).
Objective/Criterion Reference: Placeholder reference 2006 303(d)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data was collected at 15 sampling sites.
Temporal Representation: Data was collected, from 5/26/98-8/14/00, and 4/24/00-11/13/00.
Environmental Conditions:
QAPP Information: San Mateo County Environmental Health Dept. Beach Monitoring/Surfrider data/lab QA/QC used. USEPA Region IX Laboratory data used. Data evaluation was based on USEPA guidelines for 305(b) reports, that uses a hierarchy of water quality data levels. Only data of higher overall level of information (Levels 3 and 4) were used to list a water body.
QAPP Information Reference(s):