The hunt has intensified.
The Department of Natural Resources and the U.S. Fish and Wildlife Service have begun searching for Asian carp near the Stickney Water Reclamation Plant, which sits on the Chicago Area Water System in Cicero.
They're looking beyond the electric fish barrier based on water sampling that indicates the invasive species may have migrated past the barrier.
Crews are focusing on areas where warm water from industrial operations enters the waterways. Fish tend to congregate near the warmer water in the winter. Steam was rising from the water as the crews put nets up Wednesday.
To find Asian carp, they're pairing commercial netting with "electro-pushing," which basically means pushing the fish into nets using an electroshock.
"That will help us gauge what's here in a very efficient and thorough manner," said Illinois DNR Director Marc Miller. "We're going to do everything we can to keep the fish below the electric fish barrier and destroy any individuals that might be here above the barrier."
In December, officials discovered a single carp in a canal leading to Lake Michigan, the nearest the species has been found to the Great Lakes.
Environmentalists fear invasive carp could endanger the lakes' $7 billion-a-year fishing industry.