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Michigan's Statewide PCB Total Maximum Daily Load
Approved 2020 Statewide PCB TMDL Changes (Addenda)
The Michigan Department of Environment, Great Lakes, and Energy (EGLE) completed a statewide PCB Total Maximum Daily Load (TMDL) in 2013, which was approved by the United States Environmental Protection Agency (USEPA) in September 2017. The TMDL addresses most inland waterbodies not supporting designated uses for fish consumption due to exceedances of the numeric PCB water column Water Quality Standard (WQS) and/or elevated PCB concentrations in fish tissue. PCB-impaired waterbodies not covered by the statewide TMDL include the Great Lakes and connecting channels; contaminated legacy sites (i.e., Areas of Concern [AOC] and Superfund sites); and certain inland waterbodies where the level of pollutant reduction required to achieve the PCB WQS will be different than the PCB load that was calculated for the TMDL. The Statewide PCB TMDL and associated load reduction goals were developed to meet the target fish tissue concentration of 0.023 mg/kg (wet weight) based on the assumption that fish PCB concentrations will respond proportionally to reductions in atmospheric PCB loadings.
EGLE assesses fish tissue concentration data and PCB water column data on a biennial basis in accordance with our water quality monitoring strategy and our Integrated Report Assessment Methodology. Waters determined to be PCB-impaired (above the 0.023 mg/kg fish tissue target or the water column target criteria of 0.026 ng/L) and below the 0.378 mg/kg fish tissue maximum would be considered addressed by the TMDL. Waters determined to be PCB-impaired above the 0.378 mg/kg fish tissue maximum or above the ambient water column PCB concentration of 0.43 ng/L would not be considered as addressed by the TMDL.
EGLE's intent was to modify the TMDL document by updating the list of waters covered by the TMDL (as defined in Appendix A) every other year, in conjunction with the submittal of Michigan's biennial Integrated Report (IR), beginning with the 2020 version of the IR. To that end, EGLE presented a list of newly identified impaired water bodies to the public and the USEPA, which USEPA subsequently approved. Newly listed PCB-impaired water bodies have been placed in the "Impaired, TMDL completed" Integrated Report assessment category (category 4a). This updated list is based on additional water quality and fish contaminant monitoring data generated since the TMDL was finalized, and the newly identified water bodies are part of this statewide TMDL. It is EGLE's intent that no new water bodies will be added to the Integrated Report assessment category "Impaired-TMDL needed" (category 5) for PCB-impaired waters.
Statewide PCB TMDL
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.