Huge fish spurs call to 're-reverse' Chicago River

Tammy Webber -

The city was in a predicament. By the late 1800s, the slow-moving Chicago River had become a cesspool of sewage and factory pollution oozing into Lake Michigan, the source of drinking water for the bustling metropolis.

The waterway had grown so putrid that it raised fears of a disease outbreak and concerns about hurting development. So in a first-of-its-kind feat, engineers reversed the river by digging a series of canals that not only carried the stinking mess away from the lake, but also created the only shipping route between the Great Lakes and the Mississippi River.

Now a modern threat _ a voracious fish that biologists are desperate to keep out of Lake Michigan _ has spurred serious talk of undertaking another engineering feat almost as bold as the original: reversing the river again to restore its flow into the lake.

The Army Corps of Engineers is studying ways to stop invasive species from moving between two of the nation's largest watersheds, including a proposal to block the canals and undo the engineering marvel that helped define Chicago.

After the first reversal, the city at the edge of the prairie blossomed and today is known for stunning skyscrapers, a sparkling lakefront and a river dyed green every St. Patrick's Day in the heart of Chicago's downtown Loop.

The idea to reverse the river again got little traction when environmentalists suggested it a few years ago. But that was before Asian carp swam to within 25 miles of Lake Michigan, where they are being held at bay with electric barriers that deliver a nonlethal jolt. And it was before a study that showed dozens of other species were poised to move between the basins.

Adding to the urgency is the discovery last month of more carp DNA, though no actual carp, in waterways just six miles from Chicago, which could indicate that some slipped through the barriers. One live carp was found past the barrier last summer, but officials weren't sure how it got there.

The fish are rapacious eaters that can grow to 4 feet and 100 pounds, and they have been migrating up the Mississippi and its tributaries for decades. Scientists say they could decimate the Great Lakes' $7 billion-a-year fishing industry and unravel the food web by starving out native species.

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