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Great Lakes AOCs

About Milwaukee Estuary AOC

Milwaukee Estuary AOC boundary mapMilwaukee Estuary AOC Boundary Map

The Milwaukee Estuary Area of Concern is in southeast Wisconsin. It was named an Area of Concern on the Great Lakes under the Great Lakes Water Quality Agreement of 1987.

Sources of Pollution

The primary contaminants in the Milwaukee Estuary AOC are PCBs, PAHs and heavy metals. The pollution comes from both point and nonpoint sources including:

  • Historic industrial discharges
  • Wastewater treatment plants
  • Combined sewer overflows
  • Agricultural and urban runoff

The AOC is both a source of pollution to Lake Michigan and a sink for pollutants generated throughout the watershed. Pollution sources associated with land use from the entire Milwaukee River drainage basin affect its water quality.

AOC Boundaries

The AOC includes:
  • The lower 3.1 miles of the Milwaukee River downstream of North Avenue Dam
  • The lower 3 miles of the Menominee River downstream of 35th Street
  • The lower 2.5 miles of the Kinnickinnic River downstream of Chase Avenue
  • The inner and outer Harbor
  • The nearshore waters of Lake Michigan, bounded by a line extending north from Sheridan Park to the city of Milwaukee's Linnwood water intake. 

In 2008, the boundary was expanded to reflect sites that contribute large loads of contaminated sediment to the estuary.

  • Cedar Creek downstream from Bridge Road to confluence with Milwaukee River.
  • Milwaukee River from confluence with Cedar Creek to former North Avenue Dam.
  • Little Menomonee River from Brown Deer Road to confluence with Menomonee River, and Menomonee River downstream from confluence with Little Menomonee River to 35th Street.

Beneficial Use Impairments

Beneficial Use Impairments for the Great Lakes AOCs

  • Restrictions on fish and wildlife consumption
  • Eutrophication or undesirable algae
  • Degradation of fish and wildlife populations
  • Beach closings
  • Fish tumors or other deformities
  • Degradation of aesthetics
  • Bird or animal deformities or reproduction problems
  • Degradation of benthos
  • Degradation of phytoplankton and zooplankton populations
  • Restriction on dredging activities
  • Loss of fish and wildlife habitat


Restoring the Milwaukee Estuary AOC (timeline)


The US Fish and Wildlife Service convenes a technical advisory committee of 30 invited experts in area fish and wildlife and habitat restoration.  This group works to identify projects necessary to address fish, wildlife and habitat related impairments.

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WDNR Office of the Great Lakes is responsible for the development of the remedial action plan. They produce updates and devise strategies to conduct assessments, identify management actions, remove BUI’s and eventually delist the AOC. They also implement and partner on the restoration and remedial projects in the Milwaukee Estuary AOC.

A community advisory committee has been re-established by stakeholders in the Milwaukee Estuary AOC.  Through a facilitated process, a leadership team was recently formed and is working on organizing the group.  The group’s purpose is to provide input on the Remedial Action planning, building public and community support to enact recommendations of the RAP, provide a forum for meaningful and appropriate resident and local stakeholder input into remediation and restoration efforts, and advise state and federal agencies on Milwaukee Estuary AOC remediation and restoration.