| 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: |
A Source Unknown |
| Expected TMDL Completion Date: |
2022 |
| Impairment from Pollutant or Pollution: |
Pollutant |
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| Regional Board Conclusion: |
Fecal indicator bacteria (which includes enterococcus, fecal coliform, and total coliform) are being considered for listing in the CWA Section 303(d) list under Section 3.3 of the Listing Policy. Under this section a single line of evidence (LOE) is necessary to assess listing status. Two LOEs are available in the administrative record to assess indicator bacteria in this water body for the attainment of water contact recreation (REC-1) standards. Additionally, one LOE is available for the assessment of shellfish harvesting beneficial use (SHELL).
The data assessed in this decision are ocean beach bacteria data collected in accordance with AB411 (Chapter 765, Statutes of 1997) requirements. In accordance with Section 3.3 of the Listing Policy, a 4% exceedance rate shall be used to remove waters to the List "if water quality monitoring was conducted April 1 through October 31 only". However, the data assessed in this decision include data collected during months outside the April - October range. Therefore, this pollutant is being considered for addition to the section 303(d) list under section 3.3 of the Listing Policy at a 10% exceedance rate. LOEs 133693 and 133677 were not used in this assessment, because they were assessed at the 4% exceedance rate.
The following summary presents the total number of exceedances and total sample count: 1 of 12 samples exceed the Statistical Threshold Value (STV) objective for enterococcus for REC-1; 1 of 29 samples exceed the geometric mean objective for enterococcus for REC-1; and 22 of 39 samples exceed the median concentration objective for total coliform for SHELL.
Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification for adding this water segment-pollutant combination to the section 303(d) list with impaired SHELL beneficial use. 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) Enterococcus samples for the STV objective do not meet data requirements as identified in Section 3.3 of the Listing Policy. (4) Enterococcus samples for geometric means do not exceed the objective at the allowable frequency identified in Section 3.3. (5) Total coliform samples exceed the objective more than the allowable frequency identified in Section 3.3 of the Listing Policy. (6) Pursuant to Section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are met. While REC-1 beneficial use is currently supported, SHELL is impaired. |
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| 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. |
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| State Board Review of Regional Board Conclusion and Recommendation: |
|
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| State Board Decision Recommendation: |
After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board. |
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Line of Evidence (LOE) for Decision ID 105129, Indicator Bacteria
|
Region 1 |
Navarro River Beach |
|
| |
| LOE ID: |
133693 |
| |
| Pollutant: |
Enterococcus |
| LOE Subgroup: |
Pollutant-Water |
| Matrix: |
Water |
| Fraction: |
None |
| |
| Beneficial Use: |
Water Contact Recreation |
| |
| Number of Samples: |
7 |
| Number of Exceedances: |
1 |
| |
| Data and Information Type: |
PATHOGEN MONITORING |
| Data Used to Assess Water Quality: |
Water Board staff assessed Beachwatch_Mendocino County data for Navarro River Beach to determine beneficial use support and the results are as follows: 1 of the 7 samples exceeded the Statistical Threshold Value (STV) water quality standard for Enterococcus. The STV is based on a 10% exceedance rate that is calculated monthly. This data is for an AB411 beach. This LOE specifically corresponds with dry weather samples and only includes samples collected between April 1 and October 31 of each year. |
| Data Reference: |
Mendocino County Beachwatch data reformatted and renamed to match CEDEN fields. |
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| SWAMP Data: |
Non-SWAMP |
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| Water Quality Objective/Criterion: |
The bacteria water quality objective to protect the REC-1 beneficial for all ocean waters, is a Statistical Threshold Value (STV) of 110 cfu/100 mL not to be exceeded more than 10 percent of the time (calculated monthly). |
| Objective/Criterion Reference: |
California Ocean Plan Water Quality Control Plan Ocean Waters of California 2009 |
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| Evaluation Guideline: |
|
| Guideline Reference: |
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| Spatial Representation: |
The samples were collected at 1 monitoring site(s), station(s): Navarro |
| Temporal Representation: |
The samples were collected between the days of 2003-04-01 and 2003-10-28 . |
| Environmental Conditions: |
|
| QAPP Information: |
Data exempt from QAPP requirement. Draft QAPP for Mendocino County Beachwatch data used instead. Represents data collection procedure prior to development of a formal QAPP. |
| QAPP Information Reference(s): |
Draft QAPP for Mendocino County Beachwatch. Represents data collection procedure prior to development of a formal QAPP. |
| |
Line of Evidence (LOE) for Decision ID 105129, Indicator Bacteria
|
Region 1 |
Navarro River Beach |
|
| |
| LOE ID: |
133591 |
| |
| Pollutant: |
Enterococcus |
| LOE Subgroup: |
Pollutant-Water |
| Matrix: |
Water |
| Fraction: |
None |
| |
| Beneficial Use: |
Water Contact Recreation |
| |
| Number of Samples: |
12 |
| Number of Exceedances: |
1 |
| |
| Data and Information Type: |
PATHOGEN MONITORING |
| Data Used to Assess Water Quality: |
Water Board staff assessed Beachwatch_Mendocino County data for Navarro River Beach to determine beneficial use support and the results are as follows: 1 of the 12 samples exceeded the Statistical Threshold Value (STV) water quality standard for Enterococcus. The STV is based on a 10% exceedance rate that is calculated monthly. |
| Data Reference: |
Mendocino County Beachwatch data reformatted and renamed to match CEDEN fields. |
| |
| SWAMP Data: |
Non-SWAMP |
| |
| Water Quality Objective/Criterion: |
The bacteria water quality objective to protect the REC-1 beneficial for all ocean waters, is a Statistical Threshold Value (STV) of 110 cfu/100 mL not to be exceeded more than 10 percent of the time (calculated monthly). |
| Objective/Criterion Reference: |
California Ocean Plan Water Quality Control Plan Ocean Waters of California 2009 |
| |
| Evaluation Guideline: |
|
| Guideline Reference: |
| |
| Spatial Representation: |
The samples were collected at 1 monitoring site(s), station(s): Navarro |
| Temporal Representation: |
The samples were collected between the days of 2003-01-14 and 2003-12-22 . |
| Environmental Conditions: |
|
| QAPP Information: |
Data exempt from QAPP requirement. Draft QAPP for Mendocino County Beachwatch data used instead. Represents data collection procedure prior to development of a formal QAPP. |
| QAPP Information Reference(s): |
Draft QAPP for Mendocino County Beachwatch. Represents data collection procedure prior to development of a formal QAPP. |
| |
Line of Evidence (LOE) for Decision ID 105129, Indicator Bacteria
|
Region 1 |
Navarro River Beach |
|
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| LOE ID: |
133589 |
| |
| Pollutant: |
Total Coliform |
| LOE Subgroup: |
Pollutant-Water |
| Matrix: |
Water |
| Fraction: |
None |
| |
| Beneficial Use: |
Shellfish Harvesting |
| |
| Number of Samples: |
39 |
| Number of Exceedances: |
22 |
| |
| Data and Information Type: |
PATHOGEN MONITORING |
| Data Used to Assess Water Quality: |
Water Board staff assessed Beachwatch_Mendocino County data for Navarro River Beach to determine beneficial use support and the results are as follows: 22 of the 39 samples exceeded the water quality standard for Coliform, Total. The water quality standard for shellfish is based on the median concentration of Total Coliform at each station, and is calculated on a monthly basis. |
| Data Reference: |
Mendocino County Beachwatch data reformatted and renamed to match CEDEN fields. |
| |
| SWAMP Data: |
Non-SWAMP |
| |
| Water Quality Objective/Criterion: |
California Ocean Plan (SWRCB 2018) states that the median concentration of total coliform samples shall not exceed 70 per 100 ml. |
| Objective/Criterion Reference: |
California Ocean Plan Water Quality Control Plan Ocean Waters of California 2009 |
| |
| Evaluation Guideline: |
|
| Guideline Reference: |
| |
| Spatial Representation: |
The samples were collected at 1 monitoring site(s), station(s): Navarro |
| Temporal Representation: |
The samples were collected between the days of 2003-01-14 and 2003-12-22 . |
| Environmental Conditions: |
|
| QAPP Information: |
Data exempt from QAPP requirement. Draft QAPP for Mendocino County Beachwatch data used instead. Represents data collection procedure prior to development of a formal QAPP. |
| QAPP Information Reference(s): |
Draft QAPP for Mendocino County Beachwatch. Represents data collection procedure prior to development of a formal QAPP. |
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Line of Evidence (LOE) for Decision ID 105129, Indicator Bacteria
|
Region 1 |
Navarro River Beach |
|
| |
| LOE ID: |
133622 |
| |
| Pollutant: |
Enterococcus |
| LOE Subgroup: |
Pollutant-Water |
| Matrix: |
Water |
| Fraction: |
None |
| |
| Beneficial Use: |
Water Contact Recreation |
| |
| Number of Samples: |
29 |
| Number of Exceedances: |
1 |
| |
| Data and Information Type: |
PATHOGEN MONITORING |
| Data Used to Assess Water Quality: |
Water Board staff assessed Beachwatch_Mendocino County data for Navarro River Beach to determine beneficial use support and the results are as follows: 1 of the 29 samples exceeded the geomean water quality standard for Enterococcus. This is a six week rolling geomean that is calculated weekly. |
| Data Reference: |
Mendocino County Beachwatch data reformatted and renamed to match CEDEN fields. |
| |
| SWAMP Data: |
Non-SWAMP |
| |
| Water Quality Objective/Criterion: |
The bacteria water quality objective to protect the REC-1 beneficial for all ocean waters , is a six-week rolling GM of Enterococci not to exceed 30 cfu/100mL (calculated weekly). |
| Objective/Criterion Reference: |
California Ocean Plan Water Quality Control Plan Ocean Waters of California 2009 |
| |
| Evaluation Guideline: |
|
| Guideline Reference: |
| |
| Spatial Representation: |
The samples were collected at 1 monitoring site(s), station(s): Navarro |
| Temporal Representation: |
The samples were collected between the days of 2003-01-14 and 2003-12-22 . |
| Environmental Conditions: |
|
| QAPP Information: |
Data exempt from QAPP requirement. Draft QAPP for Mendocino County Beachwatch data used instead. Represents data collection procedure prior to development of a formal QAPP. |
| QAPP Information Reference(s): |
Draft QAPP for Mendocino County Beachwatch. Represents data collection procedure prior to development of a formal QAPP. |
| |
Line of Evidence (LOE) for Decision ID 105129, Indicator Bacteria
|
Region 1 |
Navarro River Beach |
|
| |
| LOE ID: |
133677 |
| |
| Pollutant: |
Enterococcus |
| LOE Subgroup: |
Pollutant-Water |
| Matrix: |
Water |
| Fraction: |
None |
| |
| Beneficial Use: |
Water Contact Recreation |
| |
| Number of Samples: |
26 |
| Number of Exceedances: |
1 |
| |
| Data and Information Type: |
PATHOGEN MONITORING |
| Data Used to Assess Water Quality: |
Water Board staff assessed Beachwatch_Mendocino County data for Navarro River Beach to determine beneficial use support and the results are as follows: 1 of the 26 samples exceeded the geomean water quality standard for Enterococcus. This is a six week rolling geomean that is calculated weekly. This data is for an AB411 beach. This LOE specifically corresponds with dry weather samples and only includes samples collected between April 1 and October 31 of each year. |
| Data Reference: |
Mendocino County Beachwatch data reformatted and renamed to match CEDEN fields. |
| |
| SWAMP Data: |
Non-SWAMP |
| |
| Water Quality Objective/Criterion: |
The bacteria water quality objective to protect the REC-1 beneficial for all ocean waters , is a six-week rolling GM of Enterococci not to exceed 30 cfu/100mL (calculated weekly). |
| Objective/Criterion Reference: |
California Ocean Plan Water Quality Control Plan Ocean Waters of California 2009 |
| |
| Evaluation Guideline: |
|
| Guideline Reference: |
| |
| Spatial Representation: |
The samples were collected at 1 monitoring site(s), station(s): Navarro |
| Temporal Representation: |
The samples were collected between the days of 2003-04-01 and 2003-10-28 . |
| Environmental Conditions: |
|
| QAPP Information: |
Data exempt from QAPP requirement. Draft QAPP for Mendocino County Beachwatch data used instead. Represents data collection procedure prior to development of a formal QAPP. |
| QAPP Information Reference(s): |
Draft QAPP for Mendocino County Beachwatch. Represents data collection procedure prior to development of a formal QAPP. |
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