As the largest freshwater bodies in the world, the Great Lakes are a pre-eminent environmental concern. At the time of the first Earth Day in 1970, it was popular to say that Lake Erie was "dead," especially since the Cayuhoga Riverthe one that caught fire in Clevelanddrained into it.
Michigan is bordered by four of the five Great Lakes, with 3,250 miles of shoreline. There have been large improvements in water quality and wildlife health in and around the Great Lakes over the past 30 years. Today it is once again possible to fish in the Great Lakes, and even to drink their water in most locations. The Great Lakes now serve as an example of how the ecological balance can be disrupted less as a byproduct of industrial activity and more as a byproduct of our interconnected world. The most significant threat to the ecological balance of the Great Lakes no longer comes mainly from industrial pollution or toxics, but from biological threats. The proliferation of zebra mussels, a non-native species that has entered the Great Lakes region chiefly in the ballast water of cargo ships, currently presents one of the more significant environmental challenges for Lake Michigan and other Great Lakes. The zebra mussel is only one of 145 non-native or "exotic" species now found in the Great Lakes. These exotic species crowd out habitat of other indigenous species in the Lakes. Yet the Great Lakes Initiative and many environmental activists continue their crusade against chlorine and other synthetic chemicals that no longer pose a serious threat to the Lakes. Professor Bill Cooper of Michigan State University comments, "If one wished to allocate scarce monetary and human resources so as to maximize the reduction in ecological risk per unit of resource expended, one would do more good by regulating and/or limiting the introduction of exotics than by obtaining marginal reductions in trace levels of existing toxicants."41 Michigan and other states have moved quickly to develop aquatic nuisance management plans, and ships transiting the Great Lakes now face a bevy of requirements designed to eliminate the discharge of biologically contaminated water.
According to the 1996 National Water Quality Inventory, all 3,250 miles of Michigan Great Lakes shoreline are considered "impaired" for some purpose, though only one mile of shoreline is classified as impaired for swimming, and only 80 miles of shoreline area are impaired for drinking. The chief problems are sediment and runoff that impair the shoreline areas for aquatic life.
On the other hand, the Great Lakes are a phenomenal success story in reducing persistent, bioaccumulative toxics such as PCBs (polychlorinated biphenyls), HCBs (hexachloro-benzene), and DDE (dichloro-diphenyl-ethylene). Charts 16 through 18 show the dramatic decline in the traces of these chemicals found in herring gull eggs in the Great Lakes.