July 18, 2014 – The locks on the Chicago River cannot be closed to prevent the migration of Asian carp, a federal appeals court has ruled.

Asian carp are large, hungry, and prolific, and if they took up residence in Lake Michigan and other Great Lakes, many believe it would be an ecological disaster. It is up to the U.S. Army Corps of Engineers to find a way to prevent the carp and other species from getting from the Mississippi River to the Great Lakes. The Chicago Area Waterway System offers five pathways, including the Chicago River.

The states of Michigan, Minnesota, Ohio, Pennsylvania, and Wisconsin had sued the Corps and the Metropolitan Water Reclamation District of Greater Chicago, seeking an injunction to close the locks of the Chicago River to prevent the fish from getting through. They lost, then appealed, but on Monday an appeals court upheld the decision.

While “the threat that the Asian carp pose to Lake Michigan has not diminished,” wrote Judge Diane Wood (left) on behalf of the three-judge panel, “we find once again that the states have not alleged facts showing that the Corps and the District are operating the [Chicago Area Waterway System] in a manner that is likely to allow the Asian carp to reach Lake Michigan.”

The court says the states can try again should “the carp pose a more immediate threat to the lakes or when the Corps and the District slacken their efforts.”

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