Keeping invaders at bay: Battle to protect Lake Michigan and the Great Lakes from invasive species paying off

Lake Michigan represents one of Illinois’ most significant recreational resources, one of its biggest economic assets and its largest public drinking water supply — benefits enjoyed by suburbanites.

That’s why local governments, environmentalists and advocates continually have their eyes on ecosystem-destroying invasive species that could enter Lake Michigan despite all the work that has limited potential invaders over the last few decades.

Since 2006, the number of new invasive species entering the Great Lakes has declined by 85%.

While the statistic suggests a global success story, it also represents the endless efforts to keep new invaders at bay. And with climate change warming the lakes, the number of freshwater species that can ultimately survive in the interconnected body of water is only increasing.

“Combating invasive species is very similar to addressing a pandemic, like COVID,” said Scott Sowa, the Great Lakes Program Director for The Nature Conservancy. “It's almost identical, so prevention is the key.”

Since the 1990s — “when people started to really wake up to the impacts of invasive species,” Sowa said — the focus has been on addressing the various vectors through which invasives are introduced.

These include recreational boats, the live pet trade, and connected channels like the Chicago area waterway system. One area that has seen significant progress is the monitoring and regular treatment of ballast water, or the water stored in a ship’s hull to provide extra weight and stability.

But some invasive species — much like COVID-19 — invariably get through these preventative measures.

“We flatten the curve, (but) we also have to focus on early detection and rapid response, and then ultimately control where we can,” Sowa said. “Because if you can detect a species early, and just like you can detect the virus early, there’s a higher probability you can contain it and possibly eradicate it.”

When faced with a body of water as large as the Great Lakes, finding an invasive species “is like finding a needle in dozens of haystacks,” Sowa added.

Groups like The Nature Conservancy are using tools such as environmental DNA and optimized surveillance frameworks to find the needle more easily. They’re also testing new ideas like selective passage, which would prevent the movement of invasive species while allowing native species.

“It's kind of funny that in the past, we created connecting channels, which took down natural barriers between the Great Lakes watershed and other watersheds. Now we're trying to build barriers to reestablish those blockades,” Sowa said. “But what that does is in some instances it prevents the movement of native species as well, and so we have to look toward selective passage.”

Selective passage would be particularly valuable in the Mississippi and Illinois rivers, where invasive carp are being held back from entering the Great Lakes by blockades. For instance, the last line of defense between the Mississippi and Lake Michigan is an electric barrier at Romeoville.

Invasive carp escaped into the Mississippi River basin during flooding in the 1970s and 1990s after being imported from Southeast Asia to help with wastewater treatment and aquaculture. Having since migrated into the Illinois River, the voracious eaters and prolific breeders have caused serious damage to native fish populations.

While strategies to keep the fish from entering the Great Lakes, such as Romeoville’s electric barrier, do provide protection, “they're not foolproof,” said Molly Flanagan, an invasive species specialist and the vice president for programs at the Alliance for the Great Lakes.

To better guard against the carp’s upstream movement, Flanagan said all eyes are on a project proposed at the Brandon Road Lock and Dam in Joliet. The $1.14 billion project would amount to what Flanagan calls a “fish gauntlet,” complete with a bubble barrier, an electric barrier and underwater acoustics.

If approved, the project would be funded by the federal, Illinois and Michigan governments, with the federal government taking on 90% of the cost.

“When you think about the economy of the Great Lakes, the jobs and businesses that it supports, the damage that invasive carp could cause if they get into the Great Lakes is billions of dollars,” Flanagan said. “They say an ounce of prevention is worth a pound of cure, and that is really true in this case, and with all invasive species. It's much easier and cheaper to keep them out than it is to try to deal with them once they get in.”

• Jenny Whidden, jwhidden@dailyherald.com, is a climate change and environment writer working with the Daily Herald through a partnership with Report For America supported by The Nature Conservancy. To help support her work with a tax-deductible donation, see dailyherald.com/rfa.