ADAPTIVE MANAGEMENT APPROACH FOR DEVELOPING POLLUTANT TRADING RATIOS CONSIDERING EQUIVALENCY AND MARGIN OF SAFETY

摘要

More than 40,000 total maximum daily loads (TMDLs) must be completed in the next 8 to 13 years, given the most recent list of impaired waters submitted to the U.S. Environmental Protection Agency (EPA). Budget requirements for the program are staggering. Most states claim that they do not have the personnel and financial resources necessary to implement the TMDL program. A March 2000 report of the General Accounting Office (GAO) highlighted the pervasive lack of data at the state level available to set water quality standards, to determine what waters are impaired, and to develop TMDLs. After the GAO report and following issuance by EPA of updated TMDL regulations, Congress requested that the National Research Council (NRC) assess the scientific basis of the TMDL program. The subsequent report “Assessing the TMDL Approach to Water Quality Management” (National Academy Press, June 2000), was issued by the eight-member NRC Committee to Assess the Scientific Basis of the TMDL Approach to Water Pollution Reduction. This report was well received, and is providing guidance to EPA in the development and implementation of new TMDL’s. This paper presents an adaptive management approach to TMDL implementation, including the development of trading ratios addressing equivalency and margin of safety, which allows for continued progress in water quality improvements in the face of uncertainty. This approach stems from the authors’ participation on the NRC TMDL Committee, and from the experience recently gained in developing TMDLs for nutrients and total dissolved solids (TDS) for the Truckee River from Lake Tahoe, CA to Pyramid Lake, NV.