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City of Waukesha water diversion

The city of Waukesha has long relied on a deep aquifer groundwater supply, but depressed water levels in the deep aquifer have compounded high radium concentration levels, requiring costly treatment. The city is under an amended court order to comply with radium standards by Sept. 1, 2023.

Waukesha sought an exception from the prohibition of diversions under the Great Lakes – St. Lawrence River Basin Water Resources Compact (compact) and the Great Lakes – St. Lawrence River Basin Sustainable Water Resources Agreement as a “community in a straddling county.” The city submitted an application for use of Lake Michigan water to the DNR in 2010 and an updated application in 2013.

Following the DNR's technical review and preliminary final environmental impact statement analysis, the city of Waukesha's Great Lakes diversion application was approved by the compact council in June 2016 with conditions that included:

  • a reduced diversion volume of 8.2 million gallons per day;
  • a smaller diversion area of only the area currently served by the Waukesha water utility;
  • monitoring wastewater impacts to the Root River; and
  • annual reporting to the Great Lakes states and provinces on the diversion.

The Great Lakes and St. Lawrence Cities Initiative requested a hearing from the compact council on the Waukesha diversion approval in August 2016. The council reviewed the petition and in April 2017 voted to not open the Waukesha civersion decision for reconsideration.


The city of Waukesha has begun the process to obtain all required federal, state and local permits and approvals necessary to construct and operate a diversion of Lake Michigan water. Waukesha plans to obtain Lake Michigan water from the city of Milwaukee and discharge treated wastewater to the Root River.

On Dec. 13, 2019, the DNR completed a final environmental impact statement (EIS) for the proposed project, and issued a determination of compliance with the Wisconsin Environmental Policy Act.

As of January 2020, the DNR has issued a waterway and wetland permit for the construction of water supply and return flow pipelines and has reissued the city of Waukesha's Wisconsin pollutant discharge elimination system (WPDES) wastewater permit, which includes conditions and requirements for the discharge of treated wastewater to the Root River. The DNR has also approved the clean water plant facility amendment. (see permits review).

The DNR will issue a final diversion approval once all required permits are issued. The final diversion approval will include all conditions of the approval required by the compact council. Construction completion and beginning of operation is currently planned for 2023.

Contact information
For information on the DNR's review of this project, contact:
Ben Callan