MADISON, Wis. -- After years of seeking approval, a Milwaukee suburb is finally set to start pulling millions of gallons of water a day from Lake Michigan to replace its polluted water supply.

       The Wisconsin Department of Natural Resources announced Tuesday that the city of Waukesha in September will start diverting up to 8.2 million gallons (about 31 million liters) of lake water per day to serve as its public water supply. The city plans to return treated wastewater to the lake via the Root River, resulting in what the DNR is calling a minimal net water loss.

       The city asked regulators in 2010 for permission to withdraw the water because its groundwater wells are contaminated with radium. The city is under a court order to find a solution.

       A compact between the Great Lakes states and Canadian provinces Quebec and Ontario generally prohibits diversions of water outside the Great Lakes basin but makes exceptions for communities in counties that straddle the basin's boundaries. Waukesha County fits that exception.

       Only the states were given legal authority to consider requests for U.S. water diversions. They approved the city of Waukesha's request in 2016. The Wisconsin DNR issued final approval for the diversion in 2021.