The USGS WGSC has outlined the following steps for a decisionmaker to take when analyzing the feasibility of offsets for meeting mercury TMDLs and discharge permit requirements. The WGSC is using these steps as a basis for conducting research in developing a decision-analytical approach to provide decision support for offset suitability in the Cache Creek watershed for mine-impacted streams.
Step 1: Establish a Regulatory Pact with the Regulatory Body
• Understand and integrate the offset program in a National Pollutant Discharge Elimination System (NPDES) Permit
• Identify key stakeholders and invite them for discussions
• Set up a monitoring/enforcement-capability/compliance schedule
• Agree on liability issues [(“good Samaritan” Laws; National Environment Policy Act (NEPA); California Environmental Quality Act (CEQA)]
Step 2: Understand the Problem: Collect and Conduct Mercury Research
• Conduct a literature review of mercury research in the defined watershed
• Delineate watershed boundaries, with RWQCB/EPA in agreement
• Collect mercury, methyl-mercury, and water-quality (for example, pH, dissolved-organic-carbon content, sulfate concentration, etc.) data
• Conduct data analysis and modeling
• Solicit expert judgment on uncertain fate and transport processes
Step 3: Model the Problem: Expressing the Uncertainty of Processes
• Construct a decision-analytical influence diagram representing the source/linkage analyses with stakeholders
• Assign probabilities representing uncertain scientific processes
• Evaluate the outcomes (meeting an environmental standard and costs of doing so) of various mitigation outcomes
Step 4: Analyze the Problem: Exploration of Mitigation Scenarios
• Explore various mitigation scenarios
• Explore decision consequences
• Explore decision tradeoffs (best possibility of meeting load-reduction requirements; minimize total abatements costs—full cost accounting).
• Identify benefits: impact of reduction on local/delta water quality; risk reduction to wildlife; risk reduction to humans/proximity to higher-risk consumers (environmental justice concerns); consistency, nexus, and contribution to other planning and management efforts; advancement of scientific knowledge; technological advancement; habitat restoration; aesthetic benefits; hazard reduction; general public interest/perception
• Analyze the offset potential on the basis of mitigation scenarios and decisions
