MERCURY TMDLs IN EPA REGION 4: RECENT CASE STUDIES

摘要

Mercury as a pollutant has emerged as a significant issue in the southeastern United States due to increased emphasis by the U.S. EPA on the Total Maximum Daily Load (TMDL) provisions of the Clean Water Act. A number of water bodies are on state 303(d) lists of impaired waters due to fish consumption advisories for mercury. In some states, settlement agreements for legal actions taken by environmental activist groups are forcing mercury TMDLs to be established on an expedited basis.rnIn February, 2000, EPA Region 4 proposed a mercury TMDL for the Savannah River, precipitated by a 303(d) listing by the State of Georgia based on consumption guidelines for mercury in fish tissue. As originally proposed, the TMDL would have had very significant consequences for NPDES permit holders on the river. Since that time, the State of Mississippi, with substantial oversight and input from Region 4, proposed and finalized a mercury TMDL for the Escatawpa River. In August, 2000, Region 4 proposed mercury TMDLs for a number of river segments listed for fish consumption guidelines in five south Georgia river basins. In November, the State of Mississippi proposed a mercury TMDL for the Bogue Chitto River, which was approved by EPA Region 4 on December 15, 2000. Also in December, 2000, EPA Region 4 re-proposed the mercury TMDL for the Savannah River, in response to the large volume of comment received on the February, 2000 proposal.rnIn advance and in support of the publication of some of these TMDLs, EPA has developed and implemented sampling and analysis programs for these rivers and watersheds. These programs have included sampling of fish tissues, sediments, water quality and watershed soils. As part of these programs, EPA has also performed one-time monitoring of certain dischargers in order to assess loadings from various source types. EPA has made a number of assumptions in their monitoring which impact how the data can be used. Dischargers need to be aware of these actions by EPA and their potential consequences.rnThis paper provides a technical and legal overview of recently proposed and published mercury TMDLs in EPA Region 4 and the data collection programs to support them. The evolution of EPA's approach to developing TMDLs for mercury is outlined. The paper concludes with a discussion of the impact of these recent developments on the pulp and paper industry.