metals resulting from historical pollution by sawmills, a paper mill, and small industries along the river. A 1996 remedial action plan for the AOC identified five "beneficial use impairments" caused by the pollution: restrictions on fish and wildlife consumption due to PCBs and heavy metals in sediments degradation of benthos, which was first documented in the 1950s and has been attributed to wood fibers and waste deposited by sawmill and paper mill operations, combined sewer overflows, and chemical wastes restrictions on dredging activities due to high levels of PCBs and heavy metals including lead, zinc, cadmium, chromium, and copper in sediments beach closings or potential restrictions on body contact due to the potential for high bacterial levels caused by combined sewer overflows loss of fish and wildlife habitat, including impacts on the site's coldwater fishery Three of these impairments have been removed from the designation (degradation of benthos in 2006, loss of fish and wildlife habitat in 2008, and beach closings in 2009) following remediation projects, which have included placement of temporary caps over contaminated areas and dredging of contaminated sediment, beginning in the 1990s. Sea lamprey A 1996 report identified the Manistique River as having the largest run of invasive sea lamprey in Lake Michigan, and a 2007 survey identified the river as the second-largest source of sea lamprey larvae in the Lake Michigan watershed. Lampreys historically were prevented from swimming upstream of the lowermost portion of the river by a dam in the city of Manistique, built in 1919. Deterioration of the dam has made it less effective as a barrier to sea lamprey, and the U.S. Fish and Wildlife Service and other agencies have developed plans to install a sea lamprey barrier at the site. References External links Hunts' Guide Rivers of Michigan Rivers of Schoolcraft County, Michigan Rivers of Alger County, Michigan Rivers of Delta County, Michigan Rivers of Luce County, Michigan Rivers of Mackinac County, Michigan Tributaries of Lake Michigan