Megan Thompson:

In fact, in 2017, an Asian carp was found beyond the barrier, about 9 miles from entering Lake Michigan. In 2010, another carp was caught about 6 miles from Lake Michigan. Carp DNA has also been detected in the waterways, and even in Lake Michigan itself. There's debate over whether the fish slipped through the barrier, or made it into the waters some other way.

The discoveries further stoked regional tensions over the issue. The state of Michigan, with its 3,300 miles of Great Lakes coastline, has long pressured Illinois to do more to stop the carp.

In 2009, Michigan and four other states sued Illinois in a bid to shut down the Chicago canals to keep carp out of Lake Michigan. The lawsuit went nowhere and other talk of taking the drastic step of closing the canals has met stiff opposition in Illinois. Because billions of dollars of freight travel through the area's waterways every year.