Preventing Environmental Contamination
Environmental Contaminants in Action in the Midwest
Protecting Eagles by Delaying Fish Passage
1989-1998
Contaminants biologists, based in the East Lansing Field Office in Michigan, investigated why bald eagles along the Great Lakes shorelines were producing far fewer young than eagles nesting inland. After close study, investigators concluded that the coastal eagles were eating fish that were contaminated with PCBs, DDE, and other chemicals from the Great Lakes. Inland eagles were consuming fish that were not tainted, and were producing more young.
Based on this information, the Contaminants Biologists recommended that the Federal Energy Regulatory Commission not require dams in the area to install fish ladders and elevators which would enable Great Lakes fish to migrate inland. This prevents the spread of this contamination to inland eagles, other wildlife, and anglers until fish from the Great Lakes are once again clean enough to safely.
The research also sparked an investigation into contamination in the Saginaw River and Bay which led to a claim against the major polluter for releases of PCBs and other contaminants. The resulting Saginaw River and Bay NRDA settlement is providing for cleanup and habitat restoration in the Saginaw watershed.
Minnesota Valley NWR, Twin Cities, Minnesota
1989-1990
Minnesota River Valley National Wildlife Refuge is located right in the heart of the Twin Cities and is prime breeding ground for ducks, geese -- and mosquitoes. Local officials approached the Service for a permit to treat the refuge with insecticides and reduce the number of mosquitoes. The refuge was concerned that the chosen pesticide, known shorthand as Bti, might also kill insects that are an important part of the diet of young waterfowl, and initially declined the request. Meanwhile Service contaminants biologists, operating out of the adjacent Twin Cities Field Office, investigated the use of the pesticide.
Initial laboratory experiments indicated that Bti could kill beneficial insects, but subsequent field studies in the refuge indicated that the actual impact would be negligible. As a result, the Service was able to permit the city to proceed with mosquito treatment in the refuge in emergency situations.
