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Rory Keane/MEDILL

Engineers reversed the flow of the Chicago River in the late 1800s to save the drinking water in Lake Michigan, and the complexion of the city has never been the same. 

Historic changes afoot for Chicago River

by Rory Keane and Lorena Villa-Parkman
March 08, 2012


Lorena Villa-Parkman/MEDILL

A few of the control measures that are being considered to stop the flow of invasive species in Illinois waterways.


Lorena Villa-Parkman

One novel control measure is a manufactured "dead zone" on the Chicago Sanitary and Ship Canal.  However, critics dismiss the idea and say it would violate federal water-quality standards set by the U.S. EPA.

Richard Hartig cast his line into the blue water off Navy Pier on a February afternoon so warm many Chicagoans were shelving their parkas in favor of light windbreakers.

He rubbed his jaw for a moment, then turned his head and said, “Well I know one thing. They’re a threat to people.”

Hartig has been fishing the waters of northern Illinois for more than 40 years. He’s seen wave after wave of invasive species come into the world’s largest freshwater system. First there was sea lamprey, then round goby, soon followed by zebra mussel, and now Asian carp. Like so many other Illinois residents, he knows just one thing about Asian carp.

Feisty newcomers like Asian carp have come along and grabbed the public’s attention, but can the prolific fish lead to a larger understanding of waterway management?

“Yeah, Asian carp are where most of the action is,” said Todd Main, deputy director of the Illinois Department of Natural Resources.

A litany of other non-native species, the carp included, have turned Hartig’s laid-back hobby into a rigorous crucible. Fishermen need to know where they’re allowed to fish, which bait shops sell approved bait, where that bait comes from, and finally they need to be responsible about where they release their bait, making sure to avoid the inadvertent transfer of species to different bodies of water. The whole process is regulated with such stringency that it hardly resembles the relaxing pastime it once was.

There are fears of a couple errant fish getting released from wild-caught bait and spawning a doomsday scenario for the Great Lakes. This is precisely why lawmakers and scientists have turned Asian carp into the poster child for nature gone awry.

“There have been pretty accurate suggestions of what might happen”, said Nancy C. Tuchman, Ph.D., vice provost and biology professor at Loyola University. “But media has popularized the idea that Asian carp can take over the Great Lakes and that they would have a great impact, however this is relative related to other invasive species.”

“They reproduce fast, however, their population density has leveled off; they are here to stay but their impact has diminished,” Tuchman said. Once they reach a certain density they can’t keep up populating the lake. They don’t have natural predators, so their numbers are controlled by lack of food.

Main and his associates at the department have ridden the vitriolic surge against the carp and turned it into a nifty cottage business.

The department is the beneficiary of Illinois’ share of money from the Great Lakes Restoration Initiative, a protective piece of legislation championed by the Obama administration and bolstered in the coming year by a fresh round of support from Washington.

The sum total for the Great Lakes Restoration Initiative comes to about $300 million, with more than $50 million allotted for battling Asian carp.

Even with all that money coming in to the state, the existing control measures have proven to be porous. Mega fauna like the carp notwithstanding, the current barriers have largely failed at stopping invasive species.

“One problem with the electric barrier is that it only stops things that are self-propelled,” said Main. That means anything that swims will be deterred, but anything that floats will get through unharmed.

Duane Chapman, a research fish biologist with the U.S. Geological Survey, said undesirable plankton have already come through. “The electronic barrier won’t do anything to stop that.”

“We have tried a number of things,” said David Jones, an environmental-studies teacher at Northeastern Illinois University, “the first being that electric field. We don’t have a lot of confidence that it’ll be working if the electricity goes out and the generator doesn’t kick in.”

“The fish tend not to like it, but what it does sometimes is stun them, and they float for a while, then recover. If they end up towards the Great Lakes side, then they’ve gone through,” he said.

“The only factors that reliably stop fishes from swimming from one place to another are: dry land and waterfalls,” said Philip W. Willink, of the fish division at The Field Museum. “Some fish species can walk over land, and a few can climb waterfalls, but fortunately Asian carp can’t.”

Beyond that unlikely fish penetrating the barrier on its own, “all it takes is some fishermen fishing on both sides…, and he takes a bucket and drops it in the river, and there you go,” said Jones.

Still, the U.S. Army Corps of Engineers has “high confidence in the effectiveness of the barriers,” according to a statement by Col. Frederic A. Drummond of the Chicago District. The Corps built and maintains the electric barrier.

Electric barriers are just one part of the current operation, which Main describes as having moved from “emergency response to management.”

Willink said no barrier technology will be 100 percent effective. “If you had to pick one method, it would be the hydrological separation; however, if you have water moving back and forth chances are greater that something is going to pass through the barrier.”

The Department of Natural Resources also employs commercial fishing crews to remove the carp from rivers. Last year, crews took more than 400 tons of Asian carp out of the Illinois River.

“It’s very tasty, but it’s got a bad rep,” said Kevin Irons of the Illinois Department of Natural Resources. Irons suggested a control measure that is getting serious looks from bureaucrats: bringing the carp to the dinner table.

“There have been efforts to promote eating Asian carp in the Midwest states, but they haven´t been successful,” said Greg Seegert, an ichthyologist in Deerfield. “The last time I heard, commercial fishermen where getting 5 cents a pound, they need 20 cents to get even.”

On the other end of the spectrum, some have been pushing for a more concrete solution. An international group called The Great Lakes Commission partnered with the St. Lawrence Cities Initiative to release a report called “Restoring the Natural Divide” at the end of January. The “Natural Divide” that the report refers to is the continental divide, the original barrier between the Great Lakes and Mississippi River watersheds.

View Aquatic Nuisance Species Control Measures Map in a larger map

Other invasive species

The impact that Asian Carp will have on the Great Lakes is still unknown. “We will know for sure only years after it happens and by then it will be too late,” Willink said.

Asian Carp eat plankton and small plants in the water, so they compete with any other species that eat plankton. Asian carp is a superior competitor and wildlife experts expect decline in the population of various species.

Zebra mussels, for example, are one of the most successful invaders in the Great Lakes. They filter water and remove small cytoplankton, which causes zooplankton to die because it doesn’t have anything to feed on. That has a cascading effect on the food web. Fingerling fish need to eat zooplankton and fish populations decline because the young ones are not able to survive.

Species such as the spiny water flea, white perch and round gobies are also a nuisance in their own way and will continue to cause major problems.

For instance, the spiny water flea has an unusual tail that looks like a fishhook. Fish yearlings try to eat the flea and the hook rips up their esophagus.

“All of these are already in Lake Michigan, the genie is out of the bottle,” said Seegert. “Once the Asian carp gets there like these other invasive species, there’s no effective control, you can´t get rid of them.”

The physical barrier is the one method that would be the most effective at keeping the Asian carp and other invasive species out of the Great Lakes. But even if there is a physical barrier that stops everything, it still isn’t leak proof.

Sound cannons, bubble curtains and strobe-light systems have been shown to be fairly effective for certain species of fish, but it’s unknown whether they would be very effective against Asian carp and other invasive species. “They are fine if you are trying to reduce the number of fish in an area, but they are not sufficient if you want to stop them completely,” said Seegert.

Regarding the lethal water temperature and chemical barriers, Tuchman said neither of them targets one species without harming anything else. “They kill almost everything.”

One proponent of the “dead zone” plan is hydrologist Donald Hey of Wetlands Research, Inc. Hey poses questions that many concerned with water quality have quickly dismissed.

“We’re gonna have to make some decisions. Do we want this presumably pristine water in what was designed to be a sanitary canal?” said Hey.

“We would have to give up this idea that all of our streams are clean. Wetlands don’t make all the waterways clean. Wetlands take nitrogen out of the water. Are we gonna take wetlands out because of this?”

While the dead zone proposal does offer a low-cost alternative to the high energy costs of other barriers, the drawbacks quickly mount up. The idea of lowering dissolved oxygen levels in the Chicago River, thereby making it toxic to aquatic life, clearly violates the U.S. EPA’s Clean Water Act.

“It’s all about opportunity,” said Irons. “There’s not one that works for everything. Even if the canal is filled in, there are things that can get through on boats going overland,” he said.

“We don’t know how things are gonna go around our manmade barriers,” he said, pointing out that the majority of invasive species in the Great Lakes arrived there in the ballast water of ships.

A comprehensive study by the U.S. Army Corps of Engineers detailing the available control measures was made public in January 2012. The commentary period has closed, and the final version of the study is expected by 2015. Some advocates of Chicago’s waterways don’t want to wait that long.

“Any of the solutions should make sure that the river continues to be improved and doesn’t sacrifice clean water,” said John Quail, spokesperson for Friends of the Chicago River. When asked whether Chicago needed to do something as monumental in scale as the reversal of the river, Quail said, “there’s room for big ideas and the time is right to do this kind of thing.”