About Great Lakes Areas of Concern (AOCs)

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The Great Lakes

The Great Lakes is a premier national aquatic resource, containing approximately 90 percent of the U.S. supply of freshwater. The geography, surface area, and volume of this freshwater resource have great economic, ecological, and societal importance; making restoration, protection, and sustainable use of the lakes a national priority.

Areas of Concern (AOCS) are watersheds, or portions of watersheds, along the Great Lakes suffering from degraded environmental conditions stemming from historic and ongoing pollution. They were designated under the U.S.-Canada Great Lakes Water Quality Agreement based on the presence of beneficial use impairments (BUIs), such as restrictions on fish and wildlife consumption, beach closures, drinking water restrictions, loss of fish and wildlife habitat, etc.

A total of 43 AOCs have been identified in the U.S. and Canada: 26 located entirely within the U.S.; 12 located wholly within Canada; and five that are shared by both countries.

Great Lakes AOCs
Great Lakes AOCs

Since the inception of the AOC program, three Canadian AOCs and four U.S. AOC have been delisted. Federal, state, provincial and local partners are working to delist the other AOCs.

Remedial Action Plans (RAPs) have been developed and are being implemented for all designated AOCs in the Great Lakes basin. RAPs were developed for each AOC to address impairments to any one of 14 beneficial uses (e.g., restrictions on fish and wildlife consumption, dredging activities, or drinking water consumption) associated with them. RAPs use an ecosystem-based, multi-media approach for assessing and remediating impaired uses. The RAP process is a model of grassroots environmental democracy, stressing empowerment of the affected public within AOCs.  Successful RAPs are community driven, with active federal, state and local involvement.

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