Final California 2020 Integrated Report (303(d) List/305(b) Report)

Supporting Information

Regional Board 2 - San Francisco Bay Region

Water Body Name:	Lake Merced
Water Body ID:	CAL2021001020020315204138
Water Body Type:	Lake & Reservoir


DECISION ID	97983	Region 2
Lake Merced

Pollutant:	Oxygen, Dissolved
Final Listing Decision:	Do Not Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not Delist from 303(d) list (TMDL required list)(2016)
Revision Status	Original
Sources:	A Source Unknown
Expected TMDL Completion Date:	2019
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 4.2 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. One hundred forty-three of two hundred thirty-six samples exceed the objective. 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 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.One hundred forty-three of two hundred thirty-six samples exceed the objective and this exceeds the allowable frequency listed in Table 4.2 of the Listing Policy. 4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are 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 97983, Oxygen, Dissolved	Region 2
Lake Merced

LOE ID:

92035

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

236

Number of Exceedances:

143

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data was collected on 60 days at varying depths (depth profiles) at four different sites in the lake. The minimum value from each stations depth profile was used to assess water quality. Among 143 of the samples collected, the minimum Dissolved Oxygen (DO) from the profile was lower than the objective specified in the basin plan and therefore did not meet the water quality objective for DO.

Data Reference:

Data for dissolved oxygen, pH, and other various pollutants in Lake Merced, May. 1997-Jul. 2010

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

For waters designated as COLD (cold freshwater habitat), the water quality objective for dissolved oxygen is a minimum level of 7.0 mg/L(Water Quality Control Plan for the San Francisco Bay Basin).

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 following locations in the lake: Lake Merced South - Pump Station Lake Merced South - Pistol Range Lake Merced North Lake Merced North East

Temporal Representation:

Samples were collected approximately 2-4 times per year from May 15th, 1997 to June 15th, 2010.

Environmental Conditions:

QAPP Information:

Quality Assurance document outlining QA procedures included with this data and signed off on by the manager of the Biological Resources Section of the SFPUC.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 97983, Oxygen, Dissolved	Region 2
Lake Merced

LOE ID:

3758

Pollutant:

Low Dissolved Oxygen

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

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:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Unspecified

Temporal Representation:

Unspecified

Environmental Conditions:

Unspecified

QAPP Information:

Unspecified

QAPP Information Reference(s):


DECISION ID	68944	Region 2
Lake Merced

Pollutant:	pH
Final Listing Decision:	Do Not Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not Delist from 303(d) list (TMDL required list)(2016)
Revision Status	Original
Sources:	A Source Unknown
Expected TMDL Completion Date:	2019
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 4.2 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Seventy of two-hundred forty samples exceed the objective. 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 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. Seventy of two-hundred forty samples exceed the objective and this exceeds the allowable frequency listed in Table 4.2 of the Listing Policy. 4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are 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 68944, pH	Region 2
Lake Merced

LOE ID:

92036

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

240

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data was collected on 61 days at varying depths (depth profiles) among four different sites in the lake. The maximum value at each station's depth profile was compared to the upper pH limit (8.5), and the minimum value at each station's depth profile was compared to the lower pH limit (6.5). If either the maximum value exceeded the upper limit or the minimum value was lower than the lower limit, then an exceedence occurred. An exceedence occurred from 143 data points.

Data Reference:

Data for dissolved oxygen, pH, and other various pollutants in Lake Merced, May. 1997-Jul. 2010

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The pH shall not be depressed below 6.5 nor raised above 8.5. This encompasses the pH range usually found in waters within the basin. Controllable water quality factors shall not cause changes greater than 0.5 units in normal ambient pH levels. (Water Quality Control Plan for the San Francisco Bay Basin)

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected at the following locations in the lake: Lake Merced South - Pump Station Lake Merced South - Pistol Range Lake Merced North Lake Merced North East

Temporal Representation:

Samples were collected approximately 2-4 times per year from May 15th, 1997 to June 15th, 2010.

Environmental Conditions:

QAPP Information:

Quality Assurance document outlining QA procedures included with this data and signed off on by the manager of the Biological Resources Section of the SFPUC.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 68944, pH	Region 2
Lake Merced

LOE ID:

3759

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

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:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Unspecified

Temporal Representation:

Unspecified

Environmental Conditions:

Unspecified

QAPP Information:

Unspecified

QAPP Information Reference(s):