Michigan asks Supreme Court to cut Great Lakes' link to Mississippi River system

Michigan asked the U.S. Supreme Court on Monday to sever a century-old connection between the Great Lakes and the Mississippi River system to prevent Asian carp from invading the lakes and endangering a $7 billion fishery.

State Attorney General Mike Cox filed a lawsuit with the nation's highest court against the state of Illinois, the U.S. Army Corps of Engineers and the Metropolitan Water Reclamation District of Greater Chicago. They operate canals and other waterways that open into Lake Michigan.

Bighead and silver carp from Asia have been detected in those waterways after migrating north for decades in the Mississippi and Illinois rivers.

Officials poisoned a section of the Chicago Sanitary and Ship Canal this month to prevent the carp from getting closer to Lake Michigan while an electrical barrier was taken down for maintenance.

But scientists say DNA found north of the barrier suggests that at least some of the carp have gotten through and may be within six miles of Lake Michigan. If so, the only other obstacles between them and the lake are shipping locks and gates, which open frequently to grant passage for cargo vessels.

The lawsuit asks that the locks and waterways be closed immediately as a stopgap measure, echoing a call by 50 members of Congress and environmental groups last week. But the suit goes further, also requesting a permanent separation between the carp-infested waters and the lakes.

That would mean cutting off a link between the Mississippi and Great Lakes basins created more than 100 years ago, when Chicago reversed the flow of the Chicago River and began sending sewage-fouled Lake Michigan water south toward the Mississippi River.

Illinois Attorney General Lisa Madigan's office was reviewing the suit and had no immediate comment, spokeswoman Natalie Bauer said.

Metropolitan Water Reclamation District spokeswoman Jill Horist said, "Even if the locks were closed, there's still a variety of ways for DNA or Asian carp to enter Lake Michigan."

Spokeswoman Lynne Whelan said the Army Corps could not comment on pending litigation.