The Des Plaines River near Lemont will have a reddish tint until Thursday because of a scientific study.
Scientists dumped a red dye "tracer" into the river between Route 83 and the Lockport area beginning late Tuesday night to study Asian carp and other species migrating to Lake Michigan.
"The idea being that if the tracer can move from the Des Plaines River, through the groundwater system into the [Chicago Sanitary and Ship Canal], there's a possibility that the carp eggs can also that," said Bob Kay, a hydrologist with the United States Geological Survey. "By using the tracer, it'll give us a better idea of where there's flow between the Des Plaines and the ship canal and it'll enable us to know where to look for carp eggs and where to do our protective barriers in the groundwater system."
The dye is harmless and will eventually be diluted to a few parts per billion, said Kay. The scientists will monitor the movement of the water until Friday, or until the dye has moved through the study area.
Asian Carp are unwanted in Lake Michigan because the compete with native fish, like salmon and walleye, for food.
"These guys are voracious feeders, some of them can get to be like 80 pounds and they eat about 40 percent of their weight every single day," said Jim Robinett, a biologist and the Vice President of Regulatory and Conservation Affairs at Chicago's Shedd Aquarium. "If you had a reproducing population, you'd have thousands of these eating a lot of plankton and wiping out the food web."
In July 2010, they were found in Lake Calumet, beyond the electric barriers constructed to keep them out of the Great Lakes. An extensive four-day search for Asian Carp in Lake Calumet three months ago came up short.
This week's tests are a part of $7 million in federal funds that were earmarked earlier this year to monitor the carp.