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

Supporting Information

Regional Board 2 - San Francisco Bay Region

Water Body Name:	Guadalupe Reservoir
Water Body ID:	CAL2054004019980928155642
Water Body Type:	Lake & Reservoir


DECISION ID	145438	Region 2
Guadalupe Reservoir

Pollutant:	Mercury
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:	Guadalupe River Watershed Mercury
TMDL Project Code:	11
Date TMDL Approved by USEPA:	06/01/2010
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal on the CWA section 303(d) List under sections 2.2 and SECTION 4.1 of the Listing Policy. Under 4.1 of the Policy, a minimum of one line of evidence is needed to assess listing status. Four lines of evidence are available in the administrative record to assess this pollutant. WILD beneficial use (Guadalupe River Watershed Objectives): LOE 307411: 1 of 1 samples exceed the Guadalupe River watershed mercury objective for fish tissue (5-15 cm in length). LOE 307412: 1 of 1 samples exceed the Guadalupe River watershed mercury objective for fish tissue (5-15 cm in length). LOE 307413: 1 of 1 samples exceed the Guadalupe River watershed mercury objective for fish tissue (15-35 cm in length). COMM beneficial use: LOE 3750 is a placeholder LOE to support a listing decision prior to 2006. 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. 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. 2 of 2 tissue samples exceed the Guadalupe River watershed mercury objective (fish 5-15 cm in length) for WILD beneficial use. 1 of 1 tissue samples exceed the Guadalupe River watershed mercury objective (fish 15-35 cm in length) for WILD beneficial use. These exceed the allowable frequency listed in Table 4.1 of the Listing Policy. 4. The Guadalupe River Mercury TMDL was approved by USEPA on 6/1/2010. 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:	Decision written by SWRCB staff.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of the available data and information, SWRCB 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.

Line of Evidence (LOE) for Decision ID 145438, Mercury	Region 2
Guadalupe Reservoir

LOE ID:

3750

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Tissue

Matrix:

Tissue

Fraction:

Not Recorded

Beneficial Use:

Commercial or recreational collection of fish, shellfish, or organisms

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:

Unspecified

Objective/Criterion Reference:

Placeholder reference pre-2006 303(d)

Evaluation Guideline:

Unspecified

Guideline Reference:

Placeholder reference pre-2006 303(d)

Spatial Representation:

Unspecified

Temporal Representation:

Unspecified

Environmental Conditions:

Unspecified

QAPP Information:

Unspecified

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 145438, Mercury	Region 2
Guadalupe Reservoir

LOE ID:

307412

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Tissue

Matrix:

Tissue

Fraction:

Fish whole body

Beneficial Use:

Wildlife Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fish tissue analysis

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RMP data for Guadalupe Reservoir to determine beneficial use support and results are as follows: 1 of 1 samples for trophic level 3 fish in the 5-15 cm size range exceed the Basin Plan's mercury fish tissue objective of 0.05 mg/kg to protect wildlife.

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, San Francisco Bay Basin, Table 3-4A Water Quality Objectives for Mercury in Waters of the Guadalupe River Watershed states, for the protection of aquatic organisms and wildlife: the water quality objective for is 0.05 mg methylmercury/kg fish in the average wet weight concentration measured in whole trophic level 3 fish with lengths 5-15 cm.

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 were collected in one location in Guadalupe Reservoir: statio 205ST0538

Temporal Representation:

Data for this line of evidence were collected on 9/24/2019

Environmental Conditions:

QAPP Information:

SWAMP Sportfish Contamination in Lakes and Reservoirs Project

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 145438, Mercury	Region 2
Guadalupe Reservoir

LOE ID:

307411

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Tissue

Matrix:

Tissue

Fraction:

Fish whole body

Beneficial Use:

Wildlife Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fish tissue analysis

Data Used to Assess Water Quality:

Water Board staff assessed Regional Board 2 Pilot Test Mercury data for Guadalupe Reservoir to determine beneficial use support and results are as follows: 1 of 1 samples for trophic level 3 fish in the 5-15 cm size range exceed the Basin Plan's mercury fish tissue objective of 0.05 mg/kg to protect wildlife.

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

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 were collected in one location in Guadalupe Reservoir: statio 205ST0538

Temporal Representation:

Data for this line of evidence were collected on 7/10/2020

Environmental Conditions:

QAPP Information:

RWB2 Pilot Tests of Mercury in Reservoirs

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 145438, Mercury	Region 2
Guadalupe Reservoir

LOE ID:

307413

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Tissue

Matrix:

Tissue

Fraction:

Fish whole body

Beneficial Use:

Wildlife Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fish tissue analysis

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RMP data for Guadalupe Reservoir to determine beneficial use support and results are as follows: 1 of 1 samples for trophic level 3 fish in the 15-35 cm size range exceed the Basin Plan's mercury fish tissue objective of 0.1 mg/kg to protect wildlife.

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, San Francisco Bay Basin, Table 3-4A Water Quality Objectives for Mercury in Waters of the Guadalupe River Watershed states, for the protection of aquatic organisms and wildlife: the water quality objective for is 0.1 mg methylmercury/kg fish in the average wet weight concentration measured in whole trophic level 3 fish with lengths 15-35 cm.

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 were collected in one location in Guadalupe Reservoir: statio 205ST0538

Temporal Representation:

Data for this line of evidence were collected on 9/24/2019

Environmental Conditions:

QAPP Information:

SWAMP Sportfish Contamination in Lakes and Reservoirs Project

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.