An Army Corps of Engineers report says sound barriers could keep Asian carp from establishing a population in the Great Lakes.
They say they'll blast the invasive species with sound at a narrow river passage in Illinois to keep them away.
The plan may keep them out of Lake Michigan, but it's more expansive than initially thought. A revised report published this week says it would cost about $778 million. Last year the estimate was $275 million.
Allen Marshall with the Army Corps of Engineers says the price went up because the project got bigger.
"There's been continuing engineering analysis that's been done, and a lot of that analysis led to a revised cost estimate," Marshall says. "We're looking at revisions to the types of materials that will be used and the construction method that will be used."
The barriers would be installed at the Brandon Road Lock in Illinois.
They're accepting public comments through December 24th. Then the project goes to congress for approval in February.