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Milwaukee Estuary AOC

What is an Area of Concern (AOC)

It's defined in the United States-Canada Great Lakes Water Quality Agreement as "a geographic area designated by the Parties where significant impairment of beneficial uses has occurred as a result of human activities at the local level." It is an area that has experienced environmental degradation. Since the identification of 43 Areas of Concern in the Great Lakes, seven have been de-listed.

Where is the Milwaukee Estuary AOC Located?

The Milwaukee Estuary was designated an Area of Concern under the Great Lakes Water Quality Agreement of 1987 because sediment impaired public benefits such as fish consumption, healthy fisheries, boat access, and wildlife habitat.

The Milwaukee River Estuary represents the meeting of the three major rivers - the Milwaukee, the Menomonee, and the Kinnickinnic Rivers - and Lake Michigan.  The boundaries of the Milwaukee Estuary AOC are shown on the map.


The Wisconsin Department of Natural Resources (WDNR) and other experts identified 11 areas of improvement called Beneficial Use Impairments (BUIs) to target here for improving our waterways.

Historical modifications and pollutants contributed to the listing of the Milwaukee Estuary Area of Concern. 

An Area of Concern is officially de-listed when all Beneficial Use Impairments or BUIs have been sufficiently restored.  Since the development of a Remedial Action Plan, much work has been completed and significant progress made towards improving conditions in the AOC. The Remedial Action Plan is periodically updated, click here to see the most recent version.

MMSD along with numerous partners is committed to making progress to eventually de-list the Area of Concern. Want to learn more about the Milwaukee Estuary Area of Concern visit WDNR’s Milwaukee Estuary Area of Concern website.

MMSD AOC Project Highlights:

MMSD is leading efforts in the following Milwaukee Estuary AOC projects. To learn about other Milwaukee Estuary AOC projects underway visit WDNR’s website.


In this video, Milwaukee historian John Gurda shares the next steps in an ambitious plan to clean up the remaining historical pollution in the rivers and harbor of the Milwaukee Estuary AOC. In scale, speed and impact, it's a historic opportunity to remove toxic pollution that is preventing our region from reaching its full potential. This project is vital to restore the health of our waterways and to open economic opportunities for Wisconsin and the Great Lakes region.

John Gurda further explains the history of pollution and the opportunities we have to clean up our rivers in this article.