| Water Body Name: | Silverado Creek |
| Water Body ID: | CAR8011200019990211132556 |
| Water Body Type: | River & Stream |
DECISION ID |
13355 |
Region 8 |
Silverado Creek |
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| Pollutant: | Escherichia coli (E. coli) |
| 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 3.3of 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. Two of 34 samples exceeded the EPA's single sample value of 236. While the frequency of measurements above this single sample value would warrant listing pursuant to the Listing Policy (Table 3.2), listing on the bases of these data is not appropriate at this time, based on the following: (1). The samples were collected on a monthly basis; insufficient samples were collected to derive geomeans. EPA has made clear in relevant guidance and regulation on EPAs bacteria criteria (e.g., Section IV B 3 of 40 CFR Part 131 (Water Quality Standards for Coastal and Great Lakes Recreation Waters; Final Rule) that the geometric mean is the more relevant value for ensuring that appropriate actions are taken to protect and improve water quality because it is a more reliable measure, being subject to less random variation and more directly linked to the underlying studies on which the 1986 bacteria criteria were based. EPA has consistently stated that the single sample standard is best used in making beach notifications and closure decisions. (2). The single sample value of 236 employed for comparative purposes is inappropriate since it is based on inappropriate assumptions regarding data variability and the intensity of recreational use at the sites (there are not designated beach areas). The value of 236 is derived based on the assumptions that (1) the log standard deviation of measured E. coli concentrations is 0.4 (essentially a default value that is assumed in the absence of adequate data/analysis), and (2) that the 75th percentile value should be selected to protect designated beach areas. EPA recommends that this percentile value be used for designated beach areas where a higher level of confidence is needed to assure that the geomean is being met. (As described in detail by EPA, single sample maximum values are statistical constructs designed to provide the assurance that geomean objectives are met. Greater confidence is needed where recreational use, and the threat of exposure, is highest; where there is limited recreational use, lower confidence is needed that the geomean is achieved.) However, the waters at issue here are not designated beach areas and receive little recreational use. Further, data variability is higher than the default value of 0.4. As a result, the applicable single sample value for comparative assessment purposes is not 236, but a higher value (which should be determined through a standards setting process; the Stormwater Quality Standards Task Force is engaged in this effort right now.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. Two of thirty-four samples exceeded the Ocean Plan's single sample standard and this standard is not appropriate on which to base listing decisions. The geometric mean standard is the appropriate standard on which to base listing decisions. The data available consists of monthly samples and geometric means can not be calculated. 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: | State Board Staff Review and Recommendation
State Water Board staff, after review, concurs with SARWQCB Decision to Do Not List the water body-pollutant combination; however, staff does not concur with all the reasons contained in the Regional Board Weight of Evidence. Listing Policy section 6.1 requires all readily available data and information shall be evaluated. In the absence of geometric mean information single sample data will be assessed. State Water Board staff agrees with the use of a water quality criteria of 235 MPN per 100ml (REC-1) resulting in two out of 34 samples exceeding the criteria. The Listing Policy shall not be used to revise water quality objectives. Section 1 of the Listing Policy states that the Policy shall not be used to establish, revise, or refine any water quality objectives or beneficial uses. |
| USEPA Action (if applicable): | |
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| LOE ID: | 21556 | ||||
| Pollutant: | Escherichia coli (E. coli) | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | None | ||||
| Beneficial Use: | Water Contact Recreation | ||||
| Number of Samples: | 34 | ||||
| Number of Exceedances: | 2 | ||||
| Data and Information Type: | PATHOGEN MONITORING | ||||
| Data Used to Assess Water Quality: | Of the 34 samples taken, 2 exceeded EPA's Recommended single sample criteria. | ||||
| Data Reference: | Orange County Coast Keeper Coastal Watersheds Project | ||||
| SWAMP Data: | Non-SWAMP | ||||
| Water Quality Objective/Criterion: | USEPA Recommended Ambient Water Quality Criteria for Bacteria -1986: E. coli: log mean less than 126 organisms/100 mL based on five or more samples per 30day period, and single sample shall not exceed 235 organisms/100mL. | ||||
| Objective/Criterion Reference: | Ambient Water Quality Criteria for Bacteria - 1986. EPA440/5-84-002 | ||||
| Evaluation Guideline: | |||||
| Guideline Reference: | |||||
| Spatial Representation: | The samples were taken at three locations: Sil1, Sil2, Sil 3.
Sil 1 - Maple Springs is located at the end of the paved section of Silverado Canyon Road just past the National forest gate, down the creek bank to the left. This area is in an area with little foot traffic. Sil 2 - Smisek: This site is named for the ranch across the street from the creek. The site is easy to find due to the large Smisek Ranch, sign overhanging the entrance of the ranch. Sil 3 - Slide Zone: This site is the lowest site on Silverado Creek at the slide zone signs. |
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| Temporal Representation: | The samples were taken monthly starting on November 23, 2002 through June 15, 2004 at Sil 2 and Sil3. The monthly samples at Sil1 were collected starting on December 13, 2002. | ||||
| Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data. | ||||
| QAPP Information: | The data's quality is deemed appropriate because it was obtained under the auspices of a QAPP approved by the Regional Board. | ||||
| QAPP Information Reference(s): | |||||
DECISION ID |
7277 |
Region 8 |
Silverado Creek |
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| Pollutant: | Pathogens |
| 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: | Unknown Nonpoint Source |
| Expected TMDL Completion Date: | 2019 |
| 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: | No new data were assessed for 2008. 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. |
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| LOE ID: | 4435 | ||||
| Pollutant: | Pathogens | ||||
| 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): | |||||
DECISION ID |
7276 |
Region 8 |
Silverado Creek |
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| Pollutant: | Salinity/TDS/Chlorides |
| 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: | Unknown Nonpoint Source |
| Expected TMDL Completion Date: | 2019 |
| 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: | No new data were assessed for 2008. 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. |
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| LOE ID: | 4436 | ||||
| Pollutant: | Salinity/TDS/Chlorides | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | Not Recorded | ||||
| Beneficial Use: | Municipal & Domestic Supply | ||||
| 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): | |||||