Grassy Island and its surrounding shoals provide habitat for fish and wildlife resources in the lower Detroit River. The island is located along the migration corridor for many bird species including osprey, bald eagle, ducks, geese, swans, and peregrine falcons. The wild celery beds along the shoals of Grassy Island provide wintering habitat for numerous waterfowl including canvasback and redhead ducks. In addition, the surrounding waters provide a diversity of habitats from shallow slow water shoals to deep flowing water with rocky shorelines thereby supporting a diverse warmwater fish community. Fish species found at the refuge include rock bass, yellow perch, walleye. Historically, lake sturgeon have spawned 1/4 mile north of Grassy Island. Lake sturgeon, are listed as either threatened or endangered by 19 of 20 states within their original range in the United States.
As the Grassy Island disposal facility was constructed without an impermeable liner or cap, the Service is concerned that wildlife in direct contact with island are being exposed to contaminants and that contaminants may be seeping into the Detroit River. The Service and the U.S. Geological Survey have conducted surveys to quantify contaminants present in the plants, biota, soils, and sediments of Grassy Island. Soils and sediments within the disposal facility have elevated concentrations of a variety of organic and inorganic compounds. The Service collected waterfowl from Grassy Island, which were found to have polychlorinated biphenyl (PCB) concentrations in excess of the U.S. Food and Drug Administration's Tolerance Level for poultry. Lead was also detected at levels of concern.
The Service is currently moving forward on plans to more fully characterize the risks from the identified contaminants and evaluate the feasibility of several approaches to both remediate contaminant risks and enhance long-term benefits of the area for fish and wildlife. The process the Service is using is the CERCLA (Comprehensive Environmental Response, Compensation, and Liability Act) framework for conducting remedial activities.
For more information concerning Grassy Island, contact:
Stephanie Millsap, Contaminants Specialist
Detroit River International Wildlife Refuge
Large Lakes Research Station
9311 Groh Road
Grosse Ile, Michigan 48138
Office: 734-692-7628 Facsimile: 734-692-7603