Draft California 2026 Integrated Report (303(d) List/305(b) Report)

Supporting Information

Regional Board 2 - San Francisco Bay Region

Water Body Name:	Aquatic Park (Marina Lagoon, San Mateo County)
Water Body ID:	CAC2044004020110713113634
Water Body Type:	Coastal & Bay Shoreline


DECISION ID	149127	Region 2
Aquatic Park (Marina Lagoon, San Mateo County)

Pollutant:	Indicator Bacteria
Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)(2018)
Revision Status	Revised
Sources:	A Source Unknown
TMDL Name:	San Francisco Bay Beaches, Pathogens
TMDL Project Code:	995
Date TMDL Approved by USEPA:	02/24/2017
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal from the CWA section 303(d) List under sections 2.2 and 4.3 of the Listing Policy. Under section 4.3 of the Policy, a minimum of one line of evidence is needed to assess listing status. Nine lines of evidence are available in the administrative record to assess this pollutant. 182 of 337 samples exceed the enterococcus geometric mean objective for water contact recreation. Based on the readily available data and information, the weight of evidence indicates that there is not sufficient justification for removing this water segment-pollutant combination from the CWA section 303(d) List. There is sufficient justification to place it in the Being Addressed portion of the CWA 303(d) List because a TMDL has been completed and approved by RWQCB and USEPA, and is expected to result in attainment of the standard. 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. 183 of 337 samples exceed the enterococcus geometric mean objective objective and these exceed the allowable frequency listed in Table 4.2 of the Listing Policy. 4. The SF Bay Beaches Pathogen TMDL was approved by USEPA on 2/24/2017. 5. Pursuant to section 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 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 149127, Indicator Bacteria	Region 2
Aquatic Park (Marina Lagoon, San Mateo County)

LOE ID:

300187

Pollutant:

Enterococcus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

GeoMean

Beneficial Use:

Water Contact Recreation

Number of Samples:

337

Number of Exceedances:

182

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed BeachWatch_San Mateo County data for Aquatic Park (Marina Lagoon, San Mateo County) to determine beneficial use support and the results are as follows: 182 of the 337 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): Aquatic Park (Aquatic Park-Aquatic Park, San Mateo).

Temporal Representation:

The samples were collected between the days of 2010-09-08 and 2020-10-12 .

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 149127, Indicator Bacteria	Region 2
Aquatic Park (Marina Lagoon, San Mateo County)

LOE ID:

300230

Pollutant:

Enterococcus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

STV

Beneficial Use:

Water Contact Recreation

Number of Samples:

109

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed BeachWatch_San Mateo County data for Aquatic Park (Marina Lagoon, San Mateo County) to determine beneficial use support and the results are as follows: 58 of the 109 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): Aquatic Park (Aquatic Park-Aquatic Park, San Mateo).

Temporal Representation:

The samples were collected between the days of 2010-09-08 and 2020-10-12 .

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 149127, Indicator Bacteria	Region 2
Aquatic Park (Marina Lagoon, San Mateo County)

LOE ID:

95962

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Non-Contact Recreation

Number of Samples:

228

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed BeachWatch data for aquatic park beach to determine beneficial use support and results are as follows: 58 of 228 samples exceed the criterion for fecal coliform.

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 Marina Lagoon (San Mateo County) was collected at 1 monitoring site [ Aquatic Park]

Temporal Representation:

Data was collected over the time period 1/4/2005-8/30/2010.

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 149127, Indicator Bacteria	Region 2
Aquatic Park (Marina Lagoon, San Mateo County)

LOE ID:

95960

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Non-Contact Recreation

Number of Samples:

208

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Seventy four of the 208 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 Aquatic Park site.

Temporal Representation:

Samples were collected from January 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 149127, Indicator Bacteria	Region 2
Aquatic Park (Marina Lagoon, San Mateo County)

LOE ID:

299905

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_San Mateo County data for Aquatic Park (Marina Lagoon, San Mateo County) to determine beneficial use support and the results are as follows: 0 of the 1 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): Aquatic Park (Aquatic Park-Aquatic Park, San Mateo).

Temporal Representation:

The samples were collected between the days of 2015-09-14 and 2015-09-14 .

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 149127, Indicator Bacteria	Region 2
Aquatic Park (Marina Lagoon, San Mateo County)

LOE ID:

95958

Pollutant:

Enterococcus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Non-Contact Recreation

Number of Samples:

202

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Seventy two of the 202 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 Aquatic Park site.

Temporal Representation:

Samples were collected from December 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 149127, Indicator Bacteria	Region 2
Aquatic Park (Marina Lagoon, San Mateo County)

LOE ID:

95959

Pollutant:

Total Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Non-Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Fifty-five of fifty-seven monthly medians exceeded the objective.

Data Reference:

Data for Region 2 Beach Watch.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The standard for total coliform states that the coliform density shall not exceed a monthly median of 240 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 Aquatic Park site.

Temporal Representation:

Samples were collected from January 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 149127, Indicator Bacteria	Region 2
Aquatic Park (Marina Lagoon, San Mateo County)

LOE ID:

95961

Pollutant:

Total Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Non-Contact Recreation

Number of Samples:

228

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed BeachWatch data for Aquatic Park beach to determine beneficial use support and results are as follows: 38 of 228 samples exceed the criterion for total coliform.

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 total coliform shall not exceed 10,000 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 Marina Lagoon (San Mateo County) was collected at 1 monitoring site [ Aquatic Park]

Temporal Representation:

Data was collected over the time period 1/4/2005-8/30/2010.

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 149127, Indicator Bacteria	Region 2
Aquatic Park (Marina Lagoon, San Mateo County)

LOE ID:

95957

Pollutant:

Enterococcus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Non-Contact Recreation

Number of Samples:

216

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed BeachWatch data for Aquatic Park Beach in Marina Lagoon to determine beneficial use support and results are as follows: 40 of 216 samples exceed the single sample maximum 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 Aquatic Park Beach (San Mateo County) was collected at 1 monitoring site [ Aquatic Park]

Temporal Representation:

Data was collected over the time period 12/5/2005-8/30/2010.

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):