TOMALES BAY / WALKER CREEK – MERCURY TMDL WORKPLAN DRAFT - TASKS, TIMEFRAMES, AND RESOURCES ARE DEPENDENT ON AVAILABILITY OF RESOURCES AND STAKEHOLDER SUPPORT
Waterbodies: Tomales Bay and Walker Creek
The goal of this TMDL is to establish and maintain environmental conditions that will, over time, result in the attainment of water beneficial uses as indicated by water, sediment and biota mercury concentrations. Our general approach is to reduce the overall bioavailable amount of mercury in the system. This will be accomplished by reducing the amount of “new” mercury entering aquatic ecosystems, removing, where feasible “old” mercury present in the system, and managing the aquatic biotransformation of mercury in order to reduce bioavailability. A key step in the TMDL allocation process will be to establish achievable and protective ambient objectives for biota, water, and sediments. These will be based on pre-mining ambient conditions. We will then develop a quantitative model to predict (1) how much loadings must be reduced and (2) what if any control measures can be implemented in order to control the biotransformation of mercury present in the system.