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

Supporting Information

Regional Board 2 - San Francisco Bay Region

Water Body Name:	Lawsons Landing
Water Body ID:	CAC2011203020070321183048
Water Body Type:	Coastal & Bay Shoreline


DECISION ID	150202	Region 2
Lawsons Landing

Pollutant:	Indicator Bacteria
Final Listing Decision:	Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Delist from 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Reason for Delisting:	Applicable WQS attained; reason for recovery unspecified
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal from the CWA 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 listing status. Fourteen lines of evidence are available in the administrative record to assess this pollutant. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification to remove this water segment-pollutant combination from 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. The lines of evidence for this water body assessed protection of water contact recreation beneficial use with enterococcus densities, non-contact recreation with fecal coliform densities and shellfish harvesting beneficial use with fecal coliform and total coliform densities. For the past 20 years the water body has been consistently meeting bacteria water quality objectives to protect water contact recreation. Only seven of one hundred nineteen samples exceed the enterococcus geometric mean objective, and this does not exceed the allowable frequency listed in Table 4.2 of the Listing Policy. There is insufficient information to determine if shellfish harvesting is impaired. Although ten of fifty-seven samples exceed the monthly median objective for total coliform which defines the listing threshold in Table 3.2 there is no supporting evidence for fecal coliform to confirm that this beneficial use is impaired. 4. Pursuant to section 3.11/4.11 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 on the section 303(d) list because applicable water quality standards for the pollutant are not 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 150202, Indicator Bacteria	Region 2
Lawsons Landing

LOE ID:

299975

Pollutant:

Enterococcus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

GeoMean

Beneficial Use:

Water Contact Recreation

Number of Samples:

191

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed BeachWatch_Marin County data for Lawsons Landing to determine beneficial use support and the results are as follows: 7 of the 191 samples exceeded the geomean water quality threshold for Enterococcus. This is a six week rolling geomean that is calculated weekly.

Data Reference:

WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The bacteria water quality objective to protect the REC-1 beneficial use where the salinity is 1 ppth or higher 95 percent or more of the time applies a six-week rolling geomean to enterococcus, not to exceed 30 cfu/100mL. (ISWEBE 2018)

Objective/Criterion Reference:

Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): LAWSONS LANDING (LAWSONS LANDING-Lawson's Landing, Marin).

Temporal Representation:

The samples were collected between the days of 2010-09-21 and 2020-10-07 .

Environmental Conditions:

QAPP Information:

State Board Staff. 2021. QAPP Reference for Beach Watch Program.

QAPP Information Reference(s):

QAPP Reference for Beach Watch Program

Line of Evidence (LOE) for Decision ID 150202, Indicator Bacteria	Region 2
Lawsons Landing

LOE ID:

90620

Pollutant:

Enterococcus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

136

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Ten of the 136 geomeans exceeded the objective.

Data Reference:

Data for Region 2 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. San Francisco Bay Basin Water Quality Control Plan.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected at the Lawson's Landing site.

Temporal Representation:

Samples were collected from April 2005 to August 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 150202, Indicator Bacteria	Region 2
Lawsons Landing

LOE ID:

90896

Pollutant:

Enterococcus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

159

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed BeachWatch data for Lawsons Landing to determine beneficial use support and results are as follows: 7 of 137 samples exceed the criterion for Enterococci.

Data Reference:

Data for Region 2 Beach Watch.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The San Francisco Bay Basin Plan states that the single sample maximum for Enterococcus shall not exceed 104 MPN/100 mL.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Lawsons Landing was collected at 1 monitoring site [ Lawson's Landing]

Temporal Representation:

Data was collected over the time period 4/5/2005-8/24/2010.

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 150202, Indicator Bacteria	Region 2
Lawsons Landing

LOE ID:

90855

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

159

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed BeachWatch data for Lawsons Landing to determine beneficial use support and results are as follows: 7 of 137 samples exceed the criterion for Enterococci.

Data Reference:

Data for Region 2 Beach Watch.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The San Francisco Bay Basin Plan states that the single sample maximum for fecal coliform shall not exceed 400 MPN/100 mL

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Lawsons Landing was collected at 1 monitoring site [ Lawson's Landing]

Temporal Representation:

Data was collected over the time period 4/5/2005-8/24/2010.

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 150202, Indicator Bacteria	Region 2
Lawsons Landing

LOE ID:

90618

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

136

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Zero of the 136 geomeans exceeded the objective.

Data Reference:

Data for Region 2 Beach Watch.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The geometric mean standard for fecal coliform states that the fecal coliform density shall not exceed 200 per 100 mL. San Francisco Bay Basin Water Quality Control Plan.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected at the Lawson's Landing site.

Temporal Representation:

Samples were collected from April 2005 to August 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 150202, Indicator Bacteria	Region 2
Lawsons Landing

LOE ID:

346

Pollutant:

Indicator Bacteria

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Available data indicate sufficient exceedances of bacterial indicator objectives. There were 9 out of 91 exceedances of the single sample maximum for enterococci, and 11 out of 78 exceedances of the geomean for enterococci (USEPA, 2007).

Data Reference:

Placeholder reference 2006 303(d)

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Title 17 C.C.R. Section 7958 states: Based on a single sample, the density of bacteria in water from each sampling station at a public beach or public water contact sports area shall not exceed:
(A) 1,000 total coliform bacteria per 100 milliliters, if the ratio of fecal/total coliform bacteria exceeds 0.1; or
(B) 10,000 total coliform bacteria per 100 milliliters; or
(C) 400 fecal coliform bacteria per 100 milliliters; or
(D) 104 enterococcus bacteria per 100 milliliters.

Based on the mean of the logarithms of the results of at least five weekly samples during any 30-day sampling period, the density of bacteria in water from any sampling station at a public beach or public water contact sports area, shall not exceed:
(A) 1,000 total coliform bacteria per 100 milliliters; or
(B) 200 fecal coliform bacteria per 100 milliliters; or
(C) 35 enterococcus bacteria per 100 milliliters. (DHS, 1999)

Objective/Criterion Reference:

Placeholder reference 2006 303(d)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Station ID# MC20

Temporal Representation:

04/01/2003-10/25/2005

Environmental Conditions:

QAPP Information:

Data record: summers 2003-2005, Marin County Health Dept.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 150202, Indicator Bacteria	Region 2
Lawsons Landing

LOE ID:

300043

Pollutant:

Total Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Median

Beneficial Use:

Shellfish Harvesting

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed BeachWatch_Marin County data for Lawsons Landing to determine beneficial use support and the results are as follows: 10 of the 57 samples exceeded the water quality threshold for Coliform, Total. The water quality threshold for shellfish is based on the median concentration at each station, and is calculated as a 30-day median.

Data Reference:

WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.1 Bacteria: Table 3-1 provides a summary of the bacterial water quality objectives and identifies the sources of those objectives. The total coliform objective for shellfish harvesting is a 30-day median less than 70 MPN/100 ML.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): LAWSONS LANDING (LAWSONS LANDING-Lawson's Landing, Marin).

Temporal Representation:

The samples were collected between the days of 2010-08-31 and 2020-10-07 .

Environmental Conditions:

QAPP Information:

State Board Staff. 2021. QAPP Reference for Beach Watch Program.

QAPP Information Reference(s):

QAPP Reference for Beach Watch Program

Line of Evidence (LOE) for Decision ID 150202, Indicator Bacteria	Region 2
Lawsons Landing

LOE ID:

299809

Pollutant:

Enterococcus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

STV

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_Marin County data for Lawsons Landing to determine beneficial use support and the results are as follows: 9 of the 71 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:

WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The bacteria water quality objective to protect the REC-1 beneficial use where the salinity is 1 ppth or higher 95 percent or more of the time applies a Statistical Threshold Value to enterococcus of 110 cfu/100 mL, not to be exceeded by more than 10 percent of samples collected within in a calendar month. (ISWEBE 2018)

Objective/Criterion Reference:

Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): LAWSONS LANDING (LAWSONS LANDING-Lawson's Landing, Marin).

Temporal Representation:

The samples were collected between the days of 2010-09-21 and 2020-10-07 .

Environmental Conditions:

QAPP Information:

State Board Staff. 2021. QAPP Reference for Beach Watch Program.

QAPP Information Reference(s):

QAPP Reference for Beach Watch Program

Line of Evidence (LOE) for Decision ID 150202, Indicator Bacteria	Region 2
Lawsons Landing

LOE ID:

299788

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

90th percentile

Beneficial Use:

Shellfish Harvesting

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed BeachWatch_Marin County data for Lawsons Landing to determine beneficial use support and the results are as follows: 1 of the 2 samples exceeded the water quality threshold for Coliform, Fecal. The water quality threshold is based on a 30-day 90% percentile.

Data Reference:

WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.1 Bacteria: Table 3-1 provides a summary of the bacterial water quality objectives and identifies the sources of those objectives. The fecal coliform objective for shellfish harvesting is a 30-day 90th percentile less than 43 MPN/100 ML.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): LAWSONS LANDING (LAWSONS LANDING-Lawson's Landing, Marin).

Temporal Representation:

The samples were collected between the days of 2015-09-09 and 2015-10-28 .

Environmental Conditions:

QAPP Information:

State Board Staff. 2021. QAPP Reference for Beach Watch Program.

QAPP Information Reference(s):

QAPP Reference for Beach Watch Program

Line of Evidence (LOE) for Decision ID 150202, Indicator Bacteria	Region 2
Lawsons Landing

LOE ID:

300001

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Mean

Beneficial Use:

Non-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_Marin County data for Lawsons Landing to determine beneficial use support and the results are as follows: 0 of the 2 samples exceeded the 30-day mean water quality threshold for Coliform, Fecal.

Data Reference:

WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.1 Bacteria: Table 3-1 provides a summary of the bacterial water quality objectives and identifies the sources of those objectives. The fecal coliform objective for non-contact recreation is a 30-day mean less than 2000 MPN/100 ML.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): LAWSONS LANDING (LAWSONS LANDING-Lawson's Landing, Marin).

Temporal Representation:

The samples were collected between the days of 2015-09-09 and 2015-10-28 .

Environmental Conditions:

QAPP Information:

State Board Staff. 2021. QAPP Reference for Beach Watch Program.

QAPP Information Reference(s):

QAPP Reference for Beach Watch Program

Line of Evidence (LOE) for Decision ID 150202, Indicator Bacteria	Region 2
Lawsons Landing

LOE ID:

299765

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Median

Beneficial Use:

Shellfish Harvesting

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.1 Bacteria: Table 3-1 provides a summary of the bacterial water quality objectives and identifies the sources of those objectives. The fecal coliform objective for shellfish harvesting is a 30-day median less than 14 MPN/100 ML.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): LAWSONS LANDING (LAWSONS LANDING-Lawson's Landing, Marin).

Temporal Representation:

The samples were collected between the days of 2015-09-09 and 2015-10-28 .

Environmental Conditions:

QAPP Information:

State Board Staff. 2021. QAPP Reference for Beach Watch Program.

QAPP Information Reference(s):

QAPP Reference for Beach Watch Program

Line of Evidence (LOE) for Decision ID 150202, Indicator Bacteria	Region 2
Lawsons Landing

LOE ID:

299767

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

90th percentile

Beneficial Use:

Non-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_Marin County data for Lawsons Landing to determine beneficial use support and the results are as follows: 0 of the 2 samples exceeded the water quality threshold for Coliform, Fecal. The water quality threshold is based on a 30-day 90% percentile.

Data Reference:

WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.1 Bacteria: Table 3-1 provides a summary of the bacterial water quality objectives and identifies the sources of those objectives. The fecal coliform objective for non-contact recreation is a 30-day 90th percentile less than 4000 MPN/100 ML.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): LAWSONS LANDING (LAWSONS LANDING-Lawson's Landing, Marin).

Temporal Representation:

The samples were collected between the days of 2015-09-09 and 2015-10-28 .

Environmental Conditions:

QAPP Information:

State Board Staff. 2021. QAPP Reference for Beach Watch Program.

QAPP Information Reference(s):

QAPP Reference for Beach Watch Program