Final California 2024 Integrated Report (303(d) List/305(b) Report)

Supporting Information

Regional Board 1 - North Coast Region

Water Body Name:	Clam Beach (near Mad River mouth)
Water Body ID:	CAC1091001120110712113517
Water Body Type:	Coastal & Bay Shoreline


DECISION ID	73281	Region 1
Clam Beach (near Mad River mouth)

Pollutant:	Indicator Bacteria
Final Listing Decision:	Do Not Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (TMDL required list)(2016)
Revision Status	Revised
Sources:	A Source Unknown
Expected TMDL Completion Date:	2022
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Fecal indicator bacteria (which includes enterococcus, fecal coliform, and total coliform) are being considered for removal from the Section 303(d) list under Section 4.3 of the Listing Policy. Five 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: three for fecal coliform and two for enterococcus. Additionally, two LOEs are available for total coliform for the attainment of shellfish harvesting (SHELL) standards. Data from LOE 47624 were re-evaluated in LOE 133641. Data from LOEs 32704 and 44432 are re-evaluated in LOEs 133615 and 133584 respectively. The data assessed in this decision are ocean beach bacteria data collected in accordance with AB411 (Chapter 765, Statutes of 1997) requirements. This pollutant was listed under section 3.3 of the Listing Policy utilizing a 10% exceedance rate for SHELL and therefore a 10% exceedance rate is being utilized to consider if this water body should be de-listed. LOEs 133707 and 133705 were not used in this assessment as they were evaluated at a 4% exceedance rate. The following summary presents number of exceedances and sample count: 1) 0 of 288 samples exceeded the geometric mean objective for enterococcus for REC-1; 2) 10 of 111 samples exceeded the statistical threshold value (STV) objective for enterococcus for REC-1; 3) 3 of 156 samples exceeded the single sample maximum objective for fecal coliform for REC-1; 4) 0 of 119 samples exceeded the geometric mean objective for fecal coliform for REC-1; 5) 136 of 327 median concentrations exceed the objective of total coliform for SHELL; and 6) than 10 percent of all samples exceed the single sample objective for total coliform for SHELL (LOE 47623). 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 satisfy the data quality requirements of Section 6.1.4 of the Policy. (2) The data used satisfy the data quantity requirements of Section 6.1.5 of the Policy. (3) Enterococcus and fecal coliform samples do not exceed the objectives for protection of REC-1 more than the allowable frequency listed in Table 4.2 of the Listing Policy. (4) Total coliform samples related to the SHELL beneficial use exceed the objectives more than the allowable frequency identified in section 4.2 of the Listing Policy. (5) Pursuant to Section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. Although it appears that REC-1 beneficial use is currently being protected, the SHELL beneficial use is impaired.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be removed from the section 303(d) list because applicable water quality standards for the pollutant are 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 73281, Indicator Bacteria	Region 1
Clam Beach (near Mad River mouth)

LOE ID:

133641

Pollutant:

Total Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Shellfish Harvesting

Number of Samples:

327

Number of Exceedances:

136

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Beachwatch_Humboldt County data for Clam Beach (near Mad River mouth) to determine beneficial use support and the results are as follows: 136 of the 327 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:

Humboldt County Beachwatch data reformatted 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): North Mad River Mouth

Temporal Representation:

The samples were collected between the days of 2004-11-16 and 2017-05-02 .

Environmental Conditions:

QAPP Information:

Data exempt from QAPP requirement. Draft QAPP for Humboldt County Beachwatch data used instead. Represents data collection procedure prior to development of a formal QAPP.

QAPP Information Reference(s):

Draft QAPP for Humboldt County Beachwatch data. Represents data collection procedure prior to development of a formal QAPP.

Line of Evidence (LOE) for Decision ID 73281, Indicator Bacteria	Region 1
Clam Beach (near Mad River mouth)

LOE ID:

47623

Pollutant:

Total Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Shellfish Harvesting

Number of Samples:

155

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

55 of 155 samples exceed the objective of 230 MPN/100mL applied as a single sample maximum for Total Coliform.

Data Reference:

Data for Region 1 Beach Watch.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Ocean Plan states the following: At all areas where shellfish may be harvested for human consumption, the following bacterial objectives shall be maintained throughout the water column: Ten percent of the samples collected during any 30-day period shall not exceed 230 MPN/100mL.

Objective/Criterion Reference:

California Ocean Plan Water Quality Control Plan Ocean Waters of California 2009

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Clam Beach (near Mad River mouth) was collected at 1 monitoring site [North Mad River Mouth]

Temporal Representation:

Data was collected over the time period 1/2/2007-8/24/2010.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The samples were collected for the Beach Watch program.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 73281, Indicator Bacteria	Region 1
Clam Beach (near Mad River mouth)

LOE ID:

47624

Pollutant:

Total Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Shellfish Harvesting

Number of Samples:

118

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

51 of 118 samples exceed the objective of 70 MPN/100mL applied as a rolling 30 day geomean for Total Coliform.

Data Reference:

Data for Region 1 Beach Watch.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Ocean Plan states that at all areas where shellfish may be harvested for human consumption, the median total coliform density shall not exceed 70 per 100 mL. Staff applied the objective as a rolling 30 day geometric mean consistent with other state bacteria objectives and with guidance from the National Shellfish Sanitation Program from which the objectives were taken.

Objective/Criterion Reference:

California Ocean Plan Water Quality Control Plan Ocean Waters of California 2009

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Clam Beach (near Mad River mouth) was collected at 1 monitoring site [North Mad River Mouth]

Temporal Representation:

Data was collected over the time period 1/2/2007-8/24/2010.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The samples were collected for the Beach Watch program.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 73281, Indicator Bacteria	Region 1
Clam Beach (near Mad River mouth)

LOE ID:

44623

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

155

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

3 of 156 samples exceed the criterion for Fecal Coliform.

Data Reference:

Data for Region 1 Beach Watch.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

California Ocean Plan (SWRCB 2009) states that the single sample maximum for fecal coliform shall not exceed 400 MPN/100 mL

Objective/Criterion Reference:

California Ocean Plan Water Quality Control Plan Ocean Waters of California 2009

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Clam Beach (near Mad River mouth) was collected at 1 monitoring site [ North Mad River Mouth]

Temporal Representation:

Data was collected over the time period 1/2/2007-8/24/2010.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The samples were collected for the Beach Watch program.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 73281, Indicator Bacteria	Region 1
Clam Beach (near Mad River mouth)

LOE ID:

133674

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Beachwatch_Humboldt County data for Clam Beach (near Mad River mouth) to determine beneficial use support and the results are as follows: 0 of the 1 samples exceeded the water quality standard for Coliform, Fecal. The water quality standard is based on a Single Sample Maximum (SSM) value that is calculated daily.

Data Reference:

Humboldt County Beachwatch data reformatted to match CEDEN fields.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

California Ocean Plan (SWRCB 2018) states that the Single Sample Maximum concentration of Fecal Coliform shall not exceed 400 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): North Mad River Mouth

Temporal Representation:

The samples were collected between the days of 2015-09-15 and 2015-09-15 .

Environmental Conditions:

QAPP Information:

Data exempt from QAPP requirement. Draft QAPP for Humboldt County Beachwatch data used instead. Represents data collection procedure prior to development of a formal QAPP.

QAPP Information Reference(s):

Draft QAPP for Humboldt County Beachwatch data. Represents data collection procedure prior to development of a formal QAPP.

Line of Evidence (LOE) for Decision ID 73281, Indicator Bacteria	Region 1
Clam Beach (near Mad River mouth)

LOE ID:

32706

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

119

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Zero of the 119 geomeans exceeded the objective.

Data Reference:

Data for Region 1 Beach Watch.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The geometric mean standard for fecal coliform states that the coliform density shall not exceed 200 MPN per 100 mL. Water Quality Control Plan for Ocean Waters (SWRCB 2009).

Objective/Criterion Reference:

California Ocean Plan Water Quality Control Plan Ocean Waters of California 2009

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected at Clam Beach near Mad River mouth.

Temporal Representation:

Samples were collected approximately once a week from 2007 to 2010.

Environmental Conditions:

QAPP Information:

The samples were collected for the beach watch program.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 73281, Indicator Bacteria	Region 1
Clam Beach (near Mad River mouth)

LOE ID:

133615

Pollutant:

Enterococcus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

288

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Beachwatch_Humboldt County data for Clam Beach (near Mad River mouth) to determine beneficial use support and the results are as follows: 0 of the 288 samples exceeded the geomean water quality standard for Enterococcus. This is a six week rolling geomean that is calculated weekly.

Data Reference:

Humboldt County Beachwatch data reformatted 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): North Mad River Mouth

Temporal Representation:

The samples were collected between the days of 2004-11-16 and 2017-05-02 .

Environmental Conditions:

QAPP Information:

Data exempt from QAPP requirement. Draft QAPP for Humboldt County Beachwatch data used instead. Represents data collection procedure prior to development of a formal QAPP.

QAPP Information Reference(s):

Draft QAPP for Humboldt County Beachwatch data. Represents data collection procedure prior to development of a formal QAPP.

Line of Evidence (LOE) for Decision ID 73281, Indicator Bacteria	Region 1
Clam Beach (near Mad River mouth)

LOE ID:

133584

Pollutant:

Enterococcus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

111

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Beachwatch_Humboldt County data for Clam Beach (near Mad River mouth) to determine beneficial use support and the results are as follows: 10 of the 111 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:

Humboldt County Beachwatch data reformatted 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): North Mad River Mouth

Temporal Representation:

The samples were collected between the days of 2004-11-16 and 2017-05-02 .

Environmental Conditions:

QAPP Information:

Data exempt from QAPP requirement. Draft QAPP for Humboldt County Beachwatch data used instead. Represents data collection procedure prior to development of a formal QAPP.

QAPP Information Reference(s):

Draft QAPP for Humboldt County Beachwatch data. Represents data collection procedure prior to development of a formal QAPP.

Line of Evidence (LOE) for Decision ID 73281, Indicator Bacteria	Region 1
Clam Beach (near Mad River mouth)

LOE ID:

32704

Pollutant:

Enterococcus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

119

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Six of the 119 geomeans exceeded the objective.

Data Reference:

Data for Region 1 Beach Watch.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The geometric mean standard for entercoccus states that the entercoccus density shall not exceed 35 per 100 mL. Water Quality Control Plan for Ocean Waters 2009.

Objective/Criterion Reference:

California Ocean Plan Water Quality Control Plan Ocean Waters of California 2009

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected at Clam Beach near Mad River mouth.

Temporal Representation:

Samples were collected approximately once a week from 2007 to 2010.

Environmental Conditions:

QAPP Information:

The samples were collected for the Beach Watch program.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 73281, Indicator Bacteria	Region 1
Clam Beach (near Mad River mouth)

LOE ID:

133705

Pollutant:

Enterococcus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Beachwatch_Humboldt County data for Clam Beach (near Mad River mouth) to determine beneficial use support and the results are as follows: 6 of the 84 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:

Humboldt County Beachwatch data reformatted to match CEDEN fields.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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): North Mad River Mouth

Temporal Representation:

The samples were collected between the days of 2005-04-05 and 2017-05-02 .

Environmental Conditions:

QAPP Information:

Data exempt from QAPP requirement. Draft QAPP for Humboldt County Beachwatch data used instead. Represents data collection procedure prior to development of a formal QAPP.

QAPP Information Reference(s):

Draft QAPP for Humboldt County Beachwatch data. Represents data collection procedure prior to development of a formal QAPP.

Line of Evidence (LOE) for Decision ID 73281, Indicator Bacteria	Region 1
Clam Beach (near Mad River mouth)

LOE ID:

44432

Pollutant:

Enterococcus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

154

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

11 of 154 samples exceed the criterion for Enterococci.

Data Reference:

Data for Region 1 Beach Watch.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

California Ocean Plan (SWRCB 2009) states that the single sample maximum for Enterococcus shall not exceed 104 MPN/100 mL.

Objective/Criterion Reference:

California Ocean Plan Water Quality Control Plan Ocean Waters of California 2009

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Clam Beach (near Mad River mouth) was collected at 1 monitoring site [ North Mad River Mouth]

Temporal Representation:

Data was collected over the time period 1/2/2007-8/24/2010.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The samples were collected for the Beach Watch program.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 73281, Indicator Bacteria	Region 1
Clam Beach (near Mad River mouth)

LOE ID:

133707

Pollutant:

Enterococcus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

280

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Beachwatch_Humboldt County data for Clam Beach (near Mad River mouth) to determine beneficial use support and the results are as follows: 0 of the 280 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:

Humboldt County Beachwatch data reformatted 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): North Mad River Mouth

Temporal Representation:

The samples were collected between the days of 2005-04-05 and 2017-05-02 .

Environmental Conditions:

QAPP Information:

Data exempt from QAPP requirement. Draft QAPP for Humboldt County Beachwatch data used instead. Represents data collection procedure prior to development of a formal QAPP.

QAPP Information Reference(s):

Draft QAPP for Humboldt County Beachwatch data. Represents data collection procedure prior to development of a formal QAPP.