Assessment of the PCB and Dioxin Background in Washington Freshwater Fish, with Recommendations for Prioritizing 303(d) Listings

摘要

Section 303(d) of the federal Clean Water Act requires states to prepare a list every two years of waterbodies that do not meet water quality standards. A Total Maximum Daily Load (TMDL) must be developed for every waterbody and pollutant on the list. A TMDL includes a written, quantitative assessment of water quality problems and pollutant sources that cause the problems. The TMDL determines the amount of a pollutant that can be discharged to the waterbody and allocates that pollutant load among sources. Washington State has approximately 90 waterbodies 303(d) listed for not meeting human health criteria for polychlorinated biphenyls (PCBs) and dioxin (2,3,7,8-TCDD) in edible fish tissue samples from rivers, lakes, and streams. In order to prioritize the states TMDL resources to address human health concerns, the Washington State Department of Ecology (Ecology) determined that better information was needed on what constitutes background levels of PCBs and dioxin in local fish populations.