# Draft 2008 California 303(d)/305(b) Integrated Report

# Supporting Information

## Regional Board 3 - Central Coast Region

Water Body Name: | Nacimiento Reservoir
Water Body ID: | CAL3098200019981214171711
Water Body Type: | Lake & Reservoir

DECISION ID | 5351
Pollutant: | Mercury
Final Listing Decision: | List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Delist from 303(d) list (TMDL required list)(2006)
Revision Status | Revised
Sources: | Surface Mining
Expected TMDL Completion Date: | 2021
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under sections 2.1 and 3.1 of the Listing Policy. One line of evidence is available in the administrative record to assess this pollutant. Based on section 3.1 the site exceeded numeric objectives for toxic pollutants. Using the binomial distribution, waters shall be placed on the section 303(d) list if the number of measured exceedances supports rejection of the null hypothesis as presented in Table 3.1. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. 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. All four tissues samples exceeded the Evaluation Guideline (OEHHA Screening Value) and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.
SWRCB Board Decision / Staff 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 it cannot be determined if applicable water quality standards are attained.
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 5351

LOE ID: | 697
Pollutant: | Mercury
LOE Subgroup: | Pollutant-Tissue
Matrix: | Tissue
Fraction: | Total
Beneficial Use: | Commercial or recreational collection of fish, shellfish, or organisms
Number of Samples: | 4
Number of Exceedances: | 4
Data and Information Type: | Fish tissue analysis
Data Used to Assess Water Quality: | Four out of 4 samples exceeded. Four filet composite samples of largemouth bass were collected (TSMP, 2002). All samples exceeded the guideline.
Data Reference: | Placeholder reference 2006 303(d)
Water Quality Objective/Criterion: | Central Coast RWQCB Basin Plan: All waters shall be maintained free of toxic substances in concentrations that are toxic to, or produce detrimental physiological responses in human, plant, animal, or aquatic life.
Objective/Criterion Reference: | Placeholder reference 2006 303(d)
Evaluation Guideline: | OEHHA Screening Value of 0.3 ug/g for mercury.
Guideline Reference: | Placeholder reference 2006 303(d)
Spatial Representation: | Two stations were sampled: Dip Creek arm of Lake Nacimiento and on Las Tablas Creek arm of Lake Nacimiento.
Temporal Representation: | Samples were collected annually in 1992-93 and 1996.
Environmental Conditions: |
QAPP Information: | Toxic Substances Monitoring Program 1992-93 Data Report. Environmental Chemistry Quality Assurance and Data Report for the Toxic Substances Monitoring Program, 1996-2000. Department of Fish and Game.
QAPP Information Reference(s):

DECISION ID | 6607
Pollutant: | Metals
Final Listing Decision: | List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | List on 303(d) list (TMDL required list)(2006)
Revision Status | Original
Sources: | Natural Sources | Surface Mining
Expected TMDL Completion Date: | 2021
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | 303(d) listing decisions made prior to 2006 were not held in an assessment database. The Regional Boards will update this decision when new data and information become available and are assessed.
RWQCB Board Decision / Staff Recommendation: | No new data were assessed for 2008. The decision has not changed.
SWRCB Board Decision / Staff Recommendation: | N/A
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 6607

LOE ID: | 3972
Pollutant: | Metals
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Not Recorded
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 0
Number of Exceedances: | 0
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)
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):