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

Supporting Information

Regional Board 3 - Central Coast Region

Water Body Name: Pacific Ocean at Sewers (San Luis Obispo), Silver Shoals Drive
Water Body ID: CAC3102402120100404172145
Water Body Type: Coastal & Bay Shoreline
 
DECISION ID
129523
Region 3     
Pacific Ocean at Sewers (San Luis Obispo), Silver Shoals Drive
 
Pollutant: Enterococcus
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)(2018)
Revision Status Revised
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 lines of evidence are available in the administrative record to assess this pollutant. Twenty-three of the 398 GM samples exceed the REC-1 enterococci water quality 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. Twenty-three of the 398 GM samples exceed the REC-1 enterococci water quality objective and this does not exceed 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.

The Water Quality Control Plan for Ocean Waters (“Ocean Plan”) contains two bacteria water quality objectives applicable to the REC-1 beneficial use: a fecal coliform water quality objective and an enterococci water quality objective. This waterbody is being considered for placement on the CWA section 303(d) List under section 3.3 of the Listing Policy, as applicable, using the enterococci objective.

In accordance with section 6.1.5.3 of the Listing Policy, data should be representative of the critical timing that the pollutant is expected to impact the waterbody. Indicator bacteria (total coliform, fecal coliform, E. coli, enterococci) populations may fluctuate substantially on a daily, seasonal, or yearly basis. Lacking constant inputs, they do not persist in the environment for a long period and effects are of relatively short duration. As a result, the historic levels of indicator bacteria in the waterbody may be a poor indicator of current risks to human health, particularly when more recent data are available to sufficiently assess the water quality standard. Additionally, water quality conditions in waterbodies may change as a result of management actions that have been implemented to address bacteria. Unrepresentative data may result in incorrectly placing or not placing a water body segment on the list, which could result in the unnecessary expenditure of public resources or missing a human health problem. Historic lines of evidence for data collected prior to 2010 were evaluated pursuant to these considerations and were not used to assess water quality standards attainment because they do not meet the temporal representation requirements of section 6.1.5.3 of the Listing Policy.

For enterococci data, Listing Policy sections 3.3 and 4.3 instructs to use the binomial distribution table in sections 3.2 and 4.2, as applicable. To use the binomial table that uses a four percent exceedance frequency, the data must be collected from coastal beaches from April 1 through October 31 only.
 
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: The Water Quality Control Plan for Ocean Waters (“Ocean Plan”) contains two bacteria water quality objectives applicable to the REC-1 beneficial use: a fecal coliform water quality objective and an enterococci water quality objective. This waterbody is being considered for placement on the CWA section 303(d) List under section 3.3 of the Listing Policy, as applicable, using the enterococci objective.

In accordance with section 6.1.5.3 of the Listing Policy, data should be representative of the critical timing that the pollutant is expected to impact the waterbody. Indicator bacteria (total coliform, fecal coliform, E. coli, enterococci) populations may fluctuate substantially on a daily, seasonal, or yearly basis. Lacking constant inputs, they do not persist in the environment for a long period and effects are of relatively short duration. As a result, the historic levels of indicator bacteria in the waterbody may be a poor indicator of current risks to human health, particularly when more recent data are available to sufficiently assess the water quality standard. Additionally, water quality conditions in waterbodies may change as a result of management actions that have been implemented to address bacteria. Unrepresentative data may result in incorrectly placing or not placing a water body segment on the list, which could result in the unnecessary expenditure of public resources or missing a human health problem. Historic lines of evidence for data collected prior to 2010 were evaluated pursuant to these considerations and were not used to assess water quality standards attainment because they do not meet the temporal representation requirements of section 6.1.5.3 of the Listing Policy.

For enterococci data, Listing Policy sections 3.3 and 4.3 instructs to use the binomial distribution table in sections 3.2 and 4.2, as applicable. To use the binomial table that uses a four percent exceedance frequency, the data must be collected from coastal beaches from April 1 through October 31 only.
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards for the pollutant are not exceeded.
 
 
Line of Evidence (LOE) for Decision ID 129523, Enterococcus
Region 3     
Pacific Ocean at Sewers (San Luis Obispo), Silver Shoals Drive
 
LOE ID: 19968
 
Pollutant: Enterococcus
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 78
Number of Exceedances: 4
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Central Coast Regional Board Staff assessed data for Pacific Ocean at Sewers (San Luis Obispo) Silver Shoals Drive to determine beneficial use support and results are as follows: 4 of 78 samples exceed the criterion for Enterococci.
Data Reference: AB 411 Data for 2004
  AB 411 Data for 2005
  AB 411 Data for 2006
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: California Ocean Plan (SWRCB 2005) states that the single sample maximum for Enterococcus shall not exceed 104 MPN/100 mL.
Objective/Criterion Reference: Water Quality Control Plan Ocean Waters of California. California Ocean Plan 2005. Sacramento, CA: State Water Resources Control Board, California Environmental Protection Agency
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Pacific Ocean at Sewers (San Luis Obispo County) was collected at one AB411 monitoring site (SEW7)
Temporal Representation: Data was collected over the time period 1/4/2005 - 6/13/2006. This includes weekly AB411 monitoring between April 1 and October 31 of each year.
Environmental Conditions:
QAPP Information: QA information not available
QAPP Information Reference(s):
 
Line of Evidence (LOE) for Decision ID 129523, Enterococcus
Region 3     
Pacific Ocean at Sewers (San Luis Obispo), Silver Shoals Drive
 
LOE ID: 217923
 
Pollutant: Enterococcus
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 398
Number of Exceedances: 23
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed data for Pacific Ocean at Sewers (San Luis Obispo), Silver Shoals Drive to determine beneficial use support and the results are as follows: 23 of the 398 samples exceeded the geomean water quality threshold for Enterococcus. This is a six week rolling geomean that is calculated weekly.
Data Reference: Data file of Region 3 Beachwatch Data. Includes data from all coastal counties in Region 3 including: , Santa Barbara, Santa Cruz, San Luis Obispo, Monterey, Ventura, and San Mateo counties.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: California Ocean Plan (SWRCB 2019) states that the bacteria water quality objective to protect the REC-1 beneficial for all ocean waters for Enterococci is a geometric mean (GM) of 30 cfu/100 mL. The waterbody GM shall not be greater that the GM magnitude in any six-week interval, calculated weekly.
Objective/Criterion Reference: SWRCB. 2005. Water Quality Control Plan, Ocean Waters of California (Ocean Plan). California Environmental Protection Agency, State Water Resources Control Board. February 2, 2019
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site(s), station(s): SEW7
Temporal Representation: The samples were collected between the days of 2010-09-07 and 2019-06-10 .
Environmental Conditions:
QAPP Information: QAPP for 2020 San Luis Obispo County Beachwatch data.
QAPP Information Reference(s): QAPP for San Luis Obispo county Beachwatch data for the 2020/2022 integrated report.
 
Line of Evidence (LOE) for Decision ID 129523, Enterococcus
Region 3     
Pacific Ocean at Sewers (San Luis Obispo), Silver Shoals Drive
 
LOE ID: 217942
 
Pollutant: Enterococcus
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 106
Number of Exceedances: 15
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed data for Pacific Ocean at Sewers (San Luis Obispo), Silver Shoals Drive to determine beneficial use support and the results are as follows: 15 of the 106 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: Data file of Region 3 Beachwatch Data. Includes data from all coastal counties in Region 3 including: , Santa Barbara, Santa Cruz, San Luis Obispo, Monterey, Ventura, and San Mateo counties.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: California Ocean Plan (SWRCB 2019) states that the bacteria water quality objective to protect the REC-1 beneficial for all ocean waters for Enterococci is a statistical value threshold (STV) of 110 cfu/100 mL. The STV shall not be exceeded by more than 10 percent of the samples collected in a calendar month, calculated in a static manner.
Objective/Criterion Reference: SWRCB. 2005. Water Quality Control Plan, Ocean Waters of California (Ocean Plan). California Environmental Protection Agency, State Water Resources Control Board. February 2, 2019
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site(s), station(s): SEW7
Temporal Representation: The samples were collected between the days of 2010-09-07 and 2019-06-10 .
Environmental Conditions:
QAPP Information: QAPP for 2020 San Luis Obispo County Beachwatch data.
QAPP Information Reference(s): QAPP for San Luis Obispo county Beachwatch data for the 2020/2022 integrated report.
 
Line of Evidence (LOE) for Decision ID 129523, Enterococcus
Region 3     
Pacific Ocean at Sewers (San Luis Obispo), Silver Shoals Drive
 
LOE ID: 19967
 
Pollutant: Enterococcus
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 36
Number of Exceedances: 3
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Central Coast Regional Board Staff assessed data for Pacific Ocean at Sewers (San Luis Obispo) Silver Shoals Drive to determine beneficial use support and results are as follows: 3 of 36 samples exceed the criterion for Enterococci.
Data Reference: AB 411 Data for 2004
  AB 411 Data for 2005
  AB 411 Data for 2006
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: California Ocean Plan (SWRCB 2005) states that the geometric mean for Enterococcus shall not exceed 35 MPN/100 mL.
Objective/Criterion Reference: Water Quality Control Plan Ocean Waters of California. California Ocean Plan 2005. Sacramento, CA: State Water Resources Control Board, California Environmental Protection Agency
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Pacific Ocean at Sewers (San Luis Obispo County) was collected at one AB411 monitoring site (SEW7)
Temporal Representation: Data was collected over the time period 1/4/2005 - 6/13/2006. This includes weekly AB411 monitoring between April 1 and October 31 of each year.
Environmental Conditions:
QAPP Information: QA information not available
QAPP Information Reference(s):
 
 
DECISION ID
72610
Region 3     
Pacific Ocean at Sewers (San Luis Obispo), Silver Shoals Drive
 
Pollutant: Fecal Coliform
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: No new data were assessed.

This pollutant is being considered for placement on the CWA section 303(d) List under sections 3.2 and 3.3 of the Listing Policy. Under these sections, 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. One of 36 samples exceeded the geometric mean standard for fecal coliform (LOE 19965) and 0 of 77 samples exceeded the single sample maximum for fecal coliform (LOE 19966) for the water contact recreation water quality standard (Water Quality Control Plan: Ocean Waters of California, SWRCB, 2005).

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. One of 36 samples exceeded the geometric mean standard for fecal coliform (LOE 19965) and 0 of 77 samples exceeded the single sample maximum for fecal coliform (LOE 19966) for the water contact recreation water quality standard and this does not exceed 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: 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 cycle. 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.
 
 
Line of Evidence (LOE) for Decision ID 72610, Fecal Coliform
Region 3     
Pacific Ocean at Sewers (San Luis Obispo), Silver Shoals Drive
 
LOE ID: 19965
 
Pollutant: Fecal Coliform
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 36
Number of Exceedances: 1
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Central Coast Regional Board Staff assessed data for Pacific Ocean at Sewers (San Luis Obispo) Silver Shoals Drive to determine beneficial use support and results are as follows: 1 of 36 samples exceed the criterion for Coliform, Fecal.
Data Reference: AB 411 Data for 2004
  AB 411 Data for 2005
  AB 411 Data for 2006
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: California Ocean Plan (SWRCB 2005) states that the 30-day geometric mean for fecal coliform shall not exceed 200 MPN/100 mL.
Objective/Criterion Reference: Water Quality Control Plan Ocean Waters of California. California Ocean Plan 2005. Sacramento, CA: State Water Resources Control Board, California Environmental Protection Agency
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Pacific Ocean at Sewers (San Luis Obispo County) was collected at one AB411 monitoring site (SEW7)
Temporal Representation: Data was collected over the time period 1/4/2005 - 6/13/2006. This includes weekly AB411 monitoring between April 1 and October 31 of each year.
Environmental Conditions:
QAPP Information: QA information not available
QAPP Information Reference(s):
 
Line of Evidence (LOE) for Decision ID 72610, Fecal Coliform
Region 3     
Pacific Ocean at Sewers (San Luis Obispo), Silver Shoals Drive
 
LOE ID: 19966
 
Pollutant: Fecal Coliform
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 77
Number of Exceedances: 0
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Central Coast Regional Board Staff assessed data for Pacific Ocean at Sewers (San Luis Obispo) Silver Shoals Drive to determine beneficial use support and results are as follows: 0 of 77 samples exceed the criterion for Coliform, Fecal.
Data Reference: AB 411 Data for 2004
  AB 411 Data for 2005
  AB 411 Data for 2006
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: California Ocean Plan (SWRCB 2005) states that the single sample maximum for fecal coliform shall not exceed 400 MPN/100 mL.
Objective/Criterion Reference: Water Quality Control Plan Ocean Waters of California. California Ocean Plan 2005. Sacramento, CA: State Water Resources Control Board, California Environmental Protection Agency
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Pacific Ocean at Sewers (San Luis Obispo County) was collected at one AB411 monitoring site (SEW7)
Temporal Representation: Data was collected over the time period 1/4/2005 - 6/13/2006. This includes weekly AB411 monitoring between April 1 and October 31 of each year.
Environmental Conditions:
QAPP Information: QA information not available
QAPP Information Reference(s):