Despite being rebuffed twice by the U.S. Supreme Court, five states filed suit Monday with a lower court demanding tougher federal and municipal action to prevent Asian carp from overrunning the Great Lakes and decimating their fishing industry.

Michigan, Wisconsin, Ohio, Minnesota and Pennsylvania said in their complaint the situation had become more dire since a live bighead carp was found last month in a Chicago-area waterway only 6 miles from where it meets Lake Michigan — well past an electric barrier designed to block the voracious fish's path.

"Asian carp will kill jobs and ruin our way of life," Michigan Attorney General Mike Cox said in a statement. "We cannot afford more bureaucratic delays — every action must be taken to protect the Great Lakes."

The suit was filed in U.S. District Court in northern Illinois. It accuses the U.S. Army Corps of Engineers and the Metropolitan Water Reclamation District of Greater Chicago of creating a public nuisance by operating locks, gates and other infrastructure through which the carp could enter the lakes.

That argument didn't convince the nation's highest court to order the locks closed earlier this year despite two requests from Michigan and other states. But the justices' rulings were procedural and did not deal with the merits of the case, Cox's spokeswoman Joy Yearout said.

The discovery of a 20-pound carp in Lake Calumet on Chicago's South Side might make a federal judge more inclined to rule favorably, said Nick Schroeck, executive director of the Great Lakes Environmental Law Center at Wayne State University. Previously, Michigan and the other states based their request largely on DNA evidence that critics dismissed as unreliable.

"It's easier to make the case that there's a public nuisance when you have this actual, live fish," Schroeck said.

The states also have had more time to develop evidence that the federal government is handling the situation so poorly it violates laws prohibiting interstate movement of harmful species, Wisconsin Attorney General J.B. Van Hollen said.

The U.S. Department of Justice, which represents the Army Corps, is reviewing the suit and will file a response later, spokesman Charles Miller said. The Chicago water district also was studying the suit and had no immediate comment, said its attorney, Frederick Feldman.

Bighead and silver carp, both Asian varieties, were imported to Deep South fish farms and sewage lagoons in the early 1970s. They escaped into the Mississippi and have been migrating north since.

Prolific and aggressive, carp gobble plankton that form a crucial link in the aquatic food chain. Scientists say if they gain a foothold in the Great Lakes, they could starve out smaller fish that are prey for sport and commercial species such as salmon, walleye and whitefish.

Silver carp also pose a safety hazard with their habit of hurtling from the water at the sound of passing motors. They have collided with boaters, sometimes causing injuries.

The carp have infested portions of the Mississippi and Illinois rivers and have been found in waterways near Chicago, where two electronic barriers were installed to block invasive species and a third is under construction. The fear that is some carp have gotten past the barriers and may soon invade Lake Michigan, and others will follow.

The Army Corps has refused to close shipping locks and gates on the waterways, saying there's no guarantee that doing so would keep the carp out of the lake. Industries that rely on shipping say closing the locks would injure the regional economy.

"Politically motivated lawsuits are not going to solve the problem," said Jim Farrell, an executive with the Illinois Chamber of Commerce. "The fish barrier is working. We've found one fish north of the barrier in 10 months of searching."

The Obama administration outlined a $78.5 million anti-carp strategy in February that focused on technological solutions such as strengthening the electric barrier and applying fish poisons where Asian carp DNA was found.

In their lawsuit, the states say those measures aren't enough. Along with closing the locks, they call for more aggressive poisoning, placing nets and other barriers at crucial points and physically separating the Great Lakes and Mississippi River watersheds.

The Corps has promised to study severing the two water systems, but the suit requests an accelerated timetable, including a final planning report within 18 months.