How the U.S. Army Corps plans to stop the spread of invasive carp in the Great Lakes

Grass Carp Photo by Shutterstock/Vladimir Wrangel

The U.S. Army Corps is using its engineering know-how to create nightmarish river obstacles designed to prevent invasive species from reaching the Great Lakes.

The plan is part of a multi-layered solution intended to contain a growing population of invasive carp in the Illinois River. Over the next six to eight years, the regiment will outfit an engineered channel in the Brandon Road Lock on the Des Plaines River, just outside Chicago, with a series of high-tech barriers that will prevent invasive carp from travelling upstream to Lake Michigan while still allowing boats to pass through.

The first barrier will be underwater speakers that emit noise at a frequency that should turn carp away from entering the channel. Next is an air bubble curtain at the entrance to the channel designed to protect against any small carp that manage to slip through gaps formed by a vessel.

Once inside the channel, there will be more acoustic deterrents, followed by an electric barrier. The Corps plan to include electric insulation in the channel to reduce the safety risk to vessel operators and lock staff. Finally, there will be a flushing lock near the end of the channel. This would shoot water downstream through the lock, carrying away any fish eggs or larvae that managed to pass through the other barriers.

Invasive Carp Deterrent
Photo Courtesy of the U.S. Army Corps

Politicians and environmental groups are in full support of the high-tech gauntlet. “Invasive species are a growing threat to our entire inland waterways system and to the countless Illinois communities and businesses that rely on strong and vibrant aquatic ecosystems,” said U.S. senator Tammy Duckworth in a statement. “The Brandon Road Project is critical in protecting the Great Lakes’ exposure to [invasive] carp.”

The invasive carp, which include black carp, grass carp, silver carp, and bighead carp, were brought to North America from Asia in the 1960s and 70s, quickly taking root in U.S. waterways, driving out native species. The carp reproduce rapidly, eating up to 20 per cent of their body weight in plankton each day. They can weigh up to 40 kilograms, reaching a metre in length.

The invasive carp have replaced all native species in certain sections of the Mississippi River, and make up 50 per cent of the fish by weight in sections of the Illinois River. Both rivers feed into the Des Plaines River, which, through the Chicago River, connects to Lake Michigan.

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Thanks to initiatives implemented by both the U.S. and Canadian governments, the carp have yet to establish themselves in the Great Lakes or any Ontario waterways. Although, a silver carp was captured in Lake Calumet, the largest body of water in Chicago, and only a few kilometres from Lake Michigan, in early August. After an intensive two-week monitoring period, no other invasive carp were spotted in the area.

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If an invasive carp did manage to find its way into the Great Lakes, experts say they could decimate the region’s $7 billion-a-year fishing industry.

“We are on the verge of an unstoppable crisis for the Great Lakes region, and now is our best chance to stop these aggressive fish from crashing our economy and environment,” said Molly Flanagan, vice president on policy for Alliance for the Great Lakes, in a statement.

In January, U.S. President Joe Biden committed $225.8 million in funding to the Brandon Road project. This is enough to start pre-construction. The estimated cost for the entire project is over $858 million.

Based on current predictions, the corps plans to award construction contracts for the channel and barriers in 2024, with work expected to be complete between 2030 and 2032.


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