COPPER AND NICKEL TMDL DEVELOPMENT LOWER SOUTH BAY

COPPER AND NICKEL TMDL DEVELOPMENT: LOWER SOUTH BAY

Presentation Overview q Scientifically Defensible Site Specific Objectives q Key Elements of the TMDL Process q Lessons Learned and Recommendations 2

Proposed SSOs for Copper and Nickel for San Francisco Bay South of the Dumbarton Bridge q Chronic 6. 9 mg/l dissolved copper 12 mg/l dissolved nickel q Acute 10. 8 mg/l dissolved copper 62. 4 mg/l dissolved nickel 3

Key Elements of the TMDL Process q Stakeholder Involvement and City of San Jose Funding and Commitment q Source Characterization q Conceptual Model Development q Impairment Assessment q Copper and Nickel Action Plans 4

Task 1 Conceptual Model Report for Copper and Nickel in Lower South San Francisco Bay

Role of the Conceptual Model in the TMDL Project q Summarize current understanding of Cu and Ni in Lower South San Francisco Bay q Communicate information to wide audience q Provide technical basis for project planning 6

Conceptual Model for Copper Concentrations in the South Bay

Average Total and Dissolved Copper Concentration (1993 -1997 Data)

Copper Inventories and Loadings in Lower South San Francisco Bay

Copper Concentrations in Lower South San Francisco Bay

Copper Mass Balance Model q Simplified but realistic: Hydrodynamics generated from 3 D model q Calculates Internal Loadings q Calculates Loading – Concentration Response

How Would Bay Respond to a 250 kg Loading Change During Wet Season? q 250 kg would be a Significant Change q Dissolved Concentrations: See bar chart q Conclude: Lower South Bay is Buffered for Cu 12

Uncertainties and Recommendations for Additional Studies q Limited Understanding of Processes in South Bay • Sedimentation/Resuspension Dynamics • Adsorption/Desorption Kinetics • Biogeochemical processes influencing metal speciation • Effects of speciation and competing metals on phytoplankton uptake and toxicity • Biological cycling in sediments and water column q Direct Data Limitation • Limited Sediment Core Data • Nonpoint source tributary loads • Food web transfer • Resuspension fluxes and other sediment-water interactions 13

Task 2 Impairment Assessment Report for Copper and Nickel in Lower South San Francisco Bay

Task 2: Impairment Assessment Purpose: To present new information and to reevaluate the determination that the beneficial uses of the South Bay are impaired due to ambient concentrations of copper and nickel. Goals: q Compile and evaluate data on ambient concentrations and toxicity information q Identify, evaluate and select indicators of beneficial-use impairment q Develop endpoints for the selected indicators q Assess levels of uncertainty q Recommend numeric values for site-specific objectives 15

Strategy to Assess Impairment of Beneficial Uses

Proposed Indicators q Individual Species Toxicity Tests q Aquatic Ecological Risk Assessment Protocol (AERAP) q Site-Specific Studies q Phytoplankton q Benthic Macroinvertebrates q Ratio of Simultaneously Extracted Metals to Acid Volatile Sulfides (SEM/AVS) q Charismatic Macrofuna: Harbor Seals and Birds 17

Phytoplankton Toxicity q Phytoplankton in laboratory experiments are sensitive to concentrations of free ionic Cu that have been measured in the South Bay q Several site-specific water quality variables that must be taken into account to predict the toxicity of free ionic copper q Insufficient data to predict the effects of free ionic Cu in the South Bay q Several unanswered questions regarding the applicability of the test results to developing water quality objectives 18

Conceptual Model for Copper Concentrations in the South Bay

Copper Uptake and Toxicity in Phytoplankton

Range of p. M+ Values in Oceanic and Estuarine Environment

Spatial and Temporal Variability in Picocyanobacteria in San Francisco Bay

Lessons Learned q Substantial amount of data and information required to implement science-based approach q Additional technical information required to support regulatory decision making process q Comprehensive monitoring programs do not meet all the information requirements of the regulatory decision-making process 24