Sampling Plan for FY2001 Aquatic Mercury Assessment at the Savannah River Site

Abstract

The State of Georgia has declared that seven segments of the Savannah River, including the reach adjacent to the Savannah River Site, are impaired for fish consumption due to high levels of mercury (U. S. EPA 2000). The Clean Water Act requires states to determine a Total Maximum Daily Load (TMDL) for pollutants that are responsible for impairment. The TMDL is the total amount of pollutant that can be assimilated by the receiving water body while achieving the water quality target that is protective of fish consumption. The U. S. Environmental Protection Agency (U. S. EPA) Region 4 issued a proposed TMDL for mercury in the Savannah River on February 8, 2000. The TMDL process establishes the allowable loading of pollutants for a water body, based on the relationship between pollution sources and in-stream water quality conditions, so that states can establish water-quality based controls to reduce pollution and restore and maintain the quality of their water resources (U. S. EPA 2000). The first phase of the proposed TMDL specifies a target mercury concentration of 1 ng/L for the Savannah River and point source discharges. The rationale for this target concentration is to protect human health from mercury toxicity caused by the consumption of contaminated fish. Due to the complexity of mercury cycling, inadequate data and difficulty in quantifying nonpoint source loads of mercury, nonpoint source loads are not considered in this first phase of the TMDL.