Illinois clears major hurdle to contain invasive fish

Silver carp are large, unwieldy and require Joe Greendyk to use both hands to size them before tossing the fish overboard into the Illinois River. The nearly 2-foot-long invasive fish, now crowding the river, has become the centerpiece of a state surveillance program to bring its growing numbers under control.

“They’re pretty slimy and pretty strong,” said Greendyk, a seasonal fisheries technician with the Illinois Natural History Survey, or INHS, his hands covered in fish slime. “So if you don’t get them right, they’re pretty hard to control.”

For decades, local, state and federal officials have feared that this voracious filter feeder, which can eat more than native fish and outgrow it, could bypass Chicago and cross the Great Lakes. The fear is that the carp, which jump out of the water and surprise boaters, could reduce populations of native species that locals love to fish for and wreak havoc on the world’s largest freshwater ecosystem and the multibillion-dollar tourism, boating and fishing industries that depend on it.

But the fight to keep carp under control and out of the Great Lakes may now become easier. Last week, the state of Illinois announced it had acquired the land needed to move along the proposed Brandon Road Interbasin, a $1.15 billion barricade aimed at preventing the aquatic menace from entering the canal that connects the Mississippi River basin to the Great Lakes.

The Brandon Road Interbasin Project, or BRIP, is an underwater defense system long considered the solution to the carp problem. The project, designed by the U.S. Army Corps of Engineers, is planned to be built on the Des Plaines River, which connects the Illinois River to the Chicago Ship Canal near suburban Joliet. The lock and dam upgrade will deploy a bubble wall, acoustic blasts, an electric barrier and a flush mechanism to prevent carp from passing through.

The infrastructure project hit a wall earlier this year due to friction between President Trump and Illinois Gov. JB Pritzker over federal funding and immigration enforcement. Trump froze more than $100 million in federal funds promised to Illinois. In response, Pritzker delayed the initial transfer of a 50-acre stretch of riverbed from Midwest Generation, the former operator of a coal-fired power plant near the proposed project site, to the state. Without it, the Army Corps would not be able to begin site preparation for the project.

But in the spring, the Army Corps told Illinois officials that it had secured funding to begin clearing rocks from the riverbed, and Pritzker and the White House resumed efforts to get the project off the ground. Allen Marshall, spokesman for the Army Corps’ Rock Island District, confirmed the phase of the project was completed in July.

Tensions rose again in late summer following Trump’s threats to send the National Guard to Chicago to fight crime and tighten immigration controls. In late August, Trump told reporters in the Oval Office that Pritzker was not cooperating with efforts to get rid of the carp. “The governor of Illinois is perhaps more affected than anyone,” Trump said. “I think until I get this request from this guy, I’m not going to do anything about it.”

Nevertheless, the megaproject is underway. Last week, Illinois officials announced they had reached an agreement Sept. 30 for the two small mountain parcels totaling 2.75 acres needed for the project. The donation, however, could end up costing Illinois taxpayers.

Previous reports from WBEZ and Grist revealed long-standing concerns by state officials about contamination by coal ash, the toxic byproduct of coal burning, at the site. Pritzker raised concerns about the cost of cleaning up the toxic mess in a 2024 letter to the Corps.

“It would be irresponsible to write a blank check to the Corps of Engineers or any other project manager without a better understanding of what we are agreeing to over the long term,” Pritzker’s spokesperson said in a statement at the time.

The Illinois Department of Natural Resources confirmed that state officials are currently developing a plan to investigate the site and reviewing whether additional land is needed.

But despite these concerns, regional leaders are moving forward with funding for the project. Earlier this month, Pritzker joined six other Great Lakes state governors in submitting a letter to Congress, calling BRIP a “national priority” and urging lawmakers to provide full federal funding for the project.

Invasive carp – a family of fish that also includes bighead carp, black carp and grass carp – first appeared in the Mississippi River about 50 years ago. Experts say the fish began invading waterways after fleeing fish farms in Arkansas, where they were imported to help limit the growth of algae and weeds. In the years that followed, the fish expanded its range throughout the river and its tributaries and began to dominate the Illinois River by the 1990s.

In 2019, INHS partnered with the Illinois Department of Natural Resources to establish a multi-agency program to track the relative abundance of carp up and down the Illinois River. Under the program, teams of ecologists capture and monitor the health of carp and native fish each year between June and October.

The data helps the state stay ahead of carp. If carp populations increase in a stretch of the river, Illinois officials can adjust incentive harvesting efforts, the state’s primary form of carp control. The program includes contracting commercial fishermen for targeted catches and paying an additional 10 cents per pound of carp. The effort appears to be working.

“Based on this data, we are reducing the population further and further,” said Michael Spear, a quantitative ecologist at INHS. “This incentive seems to be paying off. » He pointed to the area near Starved Rock State, one of the northernmost reaches of the more than 270-mile-long river, where he noted a drastic decline in the carp population over the past five years. The state Department of Natural Resources did not provide detailed estimates of carp decline at the time of publication.

Spear watched from the back of the sampling boat as Greendyk and the rest of the crew finished their work for the day. Although the data is promising, he said no one wants to know what will happen if the carp make it upriver from Chicago.

“Carp may not be present in some of these other Great Lakes states,” Spear said. “But these states are getting a lot of attention, because if they move into the Great Lakes, it’s going to become a much more regional problem.”