This article examines public involvement in the six-year administrative review of an application by Waukesha, Wisconsin, to draw water from Lake Michigan to replace its radium-contaminated local water supply. The article shows that public positions on the proposal inverted the typical relationship between partisanship and environmental attitudes, prompting both supporters and opponents to ignore scientific evidence and the central matter of water safety. In successive rounds of state and regional administrative review, these political stances induced administrators to engage in increasingly (...) legalistic forms of assessment. Although Waukesha’s application was approved in 2016, such administrative dynamics may limit the ability of the recently enacted Great Lakes Compact to address current and prospective water safety problems in the region. The case typifies an emerging pattern in water governance in the United States: contentious administrative politics drive cooperative agreements to resemble adversarial proceedings, limiting their ability to adapt to new environmental problems. (shrink)