LANSING, Mich. — After striking out with the U.S. Supreme Court, the state of Michigan and others favoring separation of the Lake Michigan and Mississippi River watersheds to prevent Asian carp from invading the Great Lakes must devise a new strategy.
The court on Monday refused to intervene for a third time. The justices turned down a plea by Michigan and six other states to revive a long-standing case involving Chicago's use of an engineered canal network to steer water from Lake Michigan toward the Mississippi.
Michigan and its allies hoped that case would be a vehicle for persuading the court to close shipping locks that could give the despised fish a passageway from Chicago-area waterways to the lake. They also wanted an order to permanently separate the two aquatic systems, linked artificially for more than a century.
The court declined to take the case in a two-sentence ruling with no explanation.
"We are pleased that the court has agreed with our position," said Lisa Madigan, attorney general of Illinois, which joined the Obama administration in opposing Michigan. Illinois "will continue its extensive work in collaboration with the federal government and all the Great Lakes states" to keep the carp out of the Great Lakes, she said.
All sides agree it's vital to ward off a carp invasion but disagree on how to do it. Biologists say the ravenous fish, weighing up to 100 pounds, could decimate the lakes' $7 billion fishing industry by gobbling plankton, a key link in the food chain that supports prized species such as salmon and walleye.
"I am appalled that the U.S. Supreme Court does not place a greater significance on protecting the Great Lakes," said Patricia Birkholz, chairwoman of the Michigan Senate's environment committee. "Once the Asian carp reach Lake Michigan, they will cause a path of destruction that will completely devastate our waters."
But Illinois officials say closing the locks would harm shipping, tour boats and other industries in the Chicago area with no guarantee of blocking the carp. A report by the state's Chamber of Commerce this month put the potential economic hit at $4.7 billion over two decades.
Michigan Attorney General Mike Cox is considering whether to file a new lawsuit in another federal court, spokesman John Sellek said. The Natural Resources Defense Council, which supported Michigan's request to the Supreme Court, said it is examining other legal options.
"This decision does not end the fight," said Henry Henderson, director of the group's Midwestern office.
But other advocates said it was time to shift attention from the courts to Congress and executive branch agencies. Another federal suit could take years, and a district judge probably would be reluctant to close the locks in the meantime after the Supreme Court twice refused to do so, said Nick Schroeck, executive director of the Great Lakes Environmental Law Center in Detroit.
"Meanwhile, the carp are knocking at the door," Schroeck said.
Legislation has been introduced in the House that would require the same actions Michigan demanded in its lawsuit. Cox said President Barack Obama should order at least temporary closure of the locks.
The Obama administration in February announced a $78.5 million carp control plan that rejected lock closure. It promises steps such as strengthening an electronic fish barrier on the Chicago Sanitary and Ship Canal and stepping up efforts to find and kill carp that might have slipped through.
None has turned up thus far, although scientists say they have detected genetic material from the carp in waterways past the barrier, which is about 25 miles from Lake Michigan, and even in the lake itself.
The U.S. Army Corps of Engineers has pledged to consider opening the locks less often. Lynn Whelan, spokeswoman for the Corps' Chicago office, said Monday there was no deadline for that decision. The administration plan calls for the Corps to release a study of a permanent separation between the two watersheds by 2012.
Advocates said the government should move more quickly. Bighead and silver carp, imported to the Deep South in the early 1970s, escaped into the Mississippi River and have migrated northward since.
They have infested the sanitary and ship canal, built a century ago as engineers reversed the flow of the Chicago River to send wastewater from Lake Michigan southward toward the Mississippi.
"Carp don't respect state lines, so the region must migrate toward the only solution we know is effective: a permanent physical separation of these two great waters," said Joel Brammeier, president of the Alliance for the Great Lakes.
Associated Press Writer Mark Sherman in Washington contributed to this report.