Importance
According to the Environmental Protection Agency’s Toxic Release Inventory, industry released over 120 million pounds of toxic waste to the air, water, or on land in Minnesota, Wisconsin, and Michigan in 2006. Similar amounts are released each year by industry in these and other states and provinces in the Great Lakes region. Some of this waste is transported elsewhere by air, some is confined to landfills, and some is degraded to harmless elements. But a portion of this waste ends up in the environment in the form of chemical contaminants that can persist for years, bioaccumulate in food webs, and become toxic to fish, wildlife, and humans.
The National Park Service has a responsibility to understand the levels and effects of these contaminants on natural systems they manage and to inform the visiting public of any human health hazards. In 2006 the NPS Great Lakes Inventory & Monitoring Network began monitoring selected contaminants that are persistent, bioaccumulative, and toxic.

For more detailed information, see the In-depth Information box below.