Polychlorinated biphenyls (PCBs) and mercury are responsible for impairing thousands of acres and miles of Michigan’s inland lakes and streams.
Waters impaired by mercury and PCBs are placed on Michigan’s Clean Water Act Section 303(d) list of water bodies. When a water resource is designated as an impaired water body on the 303(d) list, a Total Maximum Daily Load (TMDL) must be developed to determine the amount of these pollutants that can be discharged to the waterways and still meet Clean Water Act Standards.
LimnoTech worked closely with EPA Region 5 and Michigan Department of Environmental Quality (MDEQ) staff to lead development of statewide PCB and mercury TMDLs. LimnoTech developed a project database containing air, water and fish PCB and mercury data, and conducted a quality review of the data. LimnoTech also developed a GIS database containing sampling and point source locations, population, ecological drainage units, water bodies, land cover, and soils. Characterization, development of a regional approach to the TMDL, development of TMDL targets, and source identification were completed in close coordination with EPA Region 5 and MDEQ staff.
Collaboration among LimnoTech, EPA Region 5, and MDEQ staff led to the development of technically sound statewide TMDLs for mercury- and PCB-impaired inland waterbodies. The TMDLs describe the mercury and PCB load reductions necessary to achieve Clean Water Act targets and address all required TMDL elements.