Michigan's Statewide PCB Total Maximum Daily Load
EGLE has the first state program in the country to achieve a statewide TMDL for inland water bodies impacted by atmospheric deposition of PCBs. PCBs are a class of synthetic, chlorinated organic chemicals that were produced mainly for their excellent insulating capabilities and chemical stability. The United States Environmental Protection Agency banned production of PCBs in 1979 due to their toxic properties, and this class of chemicals was ultimately phased out of new uses in 1983. PCBs have been shown to cause a variety of adverse health effects, notably cancer in animals. Non-cancer effects include impacts to the nervous, immune, reproductive, and endocrine systems, among other adverse effects. PCBs concentrate in the fatty tissues of organisms and bioaccumulate in living tissues. Thus, despite the United States ban of PCB production, PCBs remain in the environment in soil, water, air, animal tissue, and vegetation. PCB concentrations in water and fish tissue have been declining since the early 1990s; however, numerous water bodies in the state remain impaired due to PCBs that continue to be found in fish tissue and water.
EGLE developed the statewide TMDL as required under Section 303(d) of the federal Clean Water Act (CWA). The federal CWA requires a TMDL to be written for water bodies not meeting Michigan's water quality standards. The purpose of the TMDL is to gather data, identify problems, and develop appropriate goals and reasonable assurance that will work toward restoring the designated uses to the water bodies.