A national group ranks the Minnesota River as the fifth most endangered river in the country.
American Rivers says the Minnesota River is threatened by mercury pollution and water drawdowns from a proposed coal-fired power plant just over the border in South Dakota.
Scott Sparlin, with the Coalition for a Clean Minnesota River, said the Big Stone II power plant would use more than six billion gallons of water every year.
"Some of it is recycled; however, we're talking about periods of drought when the lake is very sensitive, and the ecosystem downstream is very sensitive," Sparlin said. "If we have a drawdown in that time frame, doesn't matter if it gets put back into the river or not; that's when they need it the most and that's when the river needs it the most."
Big Stone II officials say the company will install state-of-the-art mercury controls on both the new plant and the existing plant. The plant will produce twice as much electricity with about half the mercury emissions, spokesman Dan Sharp says.
According to Sharp, the company has a permit to use water from Big Stone Lake, and if there's not enough water in the lake, the plant uses groundwater to produce steam.
Critics of the plant want Gov. Pawlenty to pressure South Dakota Gov. Mike Rounds to meet on the issue. The governor says he's requested a meeting through the DNR and the MPCA, but their counterparts in South Dakota have not agreed to a meeting.
Meanwhile, the Minnesota Public Utilities Commission has yet to rule on whether it will allow transmission lines to be built to bring power from the proposed plant into Minnesota.