Minnesota and eight other states are suing the Environmental Protection Agency over a rule the states say allows water pollution.
Minnesota Attorney General Lori Swanson says the EPA is allowing water to flow from one body of water to another without regulation.
Minnesota has been fighting the release of water from North Dakota's Devils Lake into the Red River. Minnesota contends the water from Devils Lake is polluted.
Swanson says the EPA rule means Minnesota is powerless to stop the polluted water.
"Under the EPA's new rule, Minnesota doesn't get a say in if or how or when that water is transferred, so it's just another way for pollution to flow into Minnesota's lakes and rivers," said Swanson.
North Dakota officials say the water is safe and its release is carefully monitored.
Swanson says the lawsuit seeks to have the EPA water transfer rule thrown out and a new rule written. She says it will likely take months or even years to resolve the dispute.
Other states are concerned about salt water from the ocean being dumped in the Great Lakes under the federal decision.
The other states suing the EPA are New York, Connecticut, Delaware, Illinois, Maine, Michigan, Missouri, Washington, and the Canadian province of Manitoba.
There was no immediate comment from the EPA.
(The Associated Press contributed to this report)