DEVELOPMENT OF A TOTAL MAXIMUM DAILY LOAD FOR MERCURY IN THE SAVANNAH RIVER BASIN

A lawsuit was brought against Region IV of the United States Environmental Protection Agency (EPA-IV) by the Sierra Club and others when EPA-IV and the State of Georgia failed to write Total Maximum Daily Loads (TMDLs) for Georgia in a timely manner. The lawsuit resulted in a consent decree that required EPA-IV to write TMDLs for Georgia on a specific timeline. One of the TMDLs EPA-IV developed was for mercury in the Savannah River Basin (SRB). The SRB runs southeast to the Atlantic Ocean and is bordered by both Georgia and South Carolina. Although SRB waters do not exceed aquatic life water quality criteria for mercury, existing fish advisories for mercury were considered by EPA-IV to be a violation of Georgia's “fishable” narrative standard, thus requiring inclusion of the SRB in Georgia's 303(d) list of impaired waters under the Clean Water Act. EPA-IV issued a proposed target concentration for mercury in the SRB of 1 part per trillion (ppt, also designated as nanograms per liter, or ng/l) in February 2000. A lengthy period of discussion with stakeholders resulted in site-specific research by EPA and a more palatable final TMDL. The final TMDL gives affected dischargers the option of meeting end-of-pipe limits for mercury of 2.8 ppt or implementing a mercury minimization plan.