Christoffer Hansen Vika/

Running the numbers on a proposal to separate the Great Lakes and the Mississippi River.

Way back in 1673, the French Canadian explorer Louis Jolliet noticed that the land around present-day Chicago had “a very great and important advantage, which perhaps will hardly be believed.” The area, he foresaw, could become the great node of a huge continent, with the Great Lakes on one side and, just a few miles to the southwest, the Illinois River and the entire Mississippi Basin. Jolliet envisioned, rather hopefully, that connecting the two — and creating a water route from Lake Erie all the way to the Gulf of Mexico – would be as simple as building a canal through just “half a league of prairie.”

The reality, of course, turned out to be far more complicated and expensive. It would be nearly 200 years before the first, 96-mile connection — the Illinois and Michigan Canal — was completed, and another 50 before the current connection — the Chicago Sanitary and Ship Canal — opened its locks for the first time. Finished in 1900, the latter canal created a shorter, 28-mile route linking the two waterways. Even more significantly, it was engineered to reverse the flow of the Chicago River and instead carry the growing city’s wastewater away from its drinking supply in Lake Michigan. By moving then-untreated waste away from the crown jewel of the lake, Chicago was able to put off dealing with many of the consequences of man-made intervention in the Midwest's ecosystem.

But after more than a hundred years, it looks as though it's time to pay the price. And it’s going to be an expensive one.

Over the last decade or so, a huge range of interests — from environmental groups to fishermen to shipping experts to politicians — have raised the alarm over just how much this artificial connection has created an opening for invasive species such as the Asian carp to make their way through North America’s waterways. And the costs associated with the damage caused by these species have been high enough to prompt serious consideration of closing off the link between the Mississippi and the Great Lakes.

How high? First, consider the figure $18 billion. That’s the estimate the U.S. Army Corps of Engineers released last week to re-insert a physical separation between the Great Lakes and the Mississippi system. The full report, the Great Lakes and Interbasin Mississippi River Study, was commissioned by Congress to address the growing threat of invasive species in the area known as the Chicago Area Waterway System. The final report details a wide spectrum of actions — ranging from essentially maintaining the status quo to engineering a complete separation over a 25-year period — but doesn’t offer recommendations on which course to take.

$18 billion sounds like a lot of money, an especially huge amount for a deadlocked federal government to put aside for what on the surface sounds like an environmentalist’s pet project. But an accounting of both the costs and benefits, as well as the history of what’s already been put into this project, makes a compelling case for figuring out a real solution to the problem. Let's look at the numbers:

$500 million: The estimated annual cost spent on controlling the population of the invasive zebra and quagga mussels in the Great Lakes basin. The zebra mussel, native to Eastern Europe, reached the Great Lakes in the 1980s. By 2005, nearly 98 percent of all mussels collected in Lake Michigan were one of these invasive species. Using these costs as a guideline, researchers at the Great Lakes Commission and the Great Lakes and St. Lawrence Cities Initiative argued for a complete restoration of the natural divide in a 2012 report, concluding that “stopping a single AIS [aquatic invasive species] from transferring between basins could avoid billions of dollars in economic loss.”

20: The breeding population of Asian carp necessary to establish a foothold in the Great Lakes, according to a 2012 report from the Canadian government. Currently, a series of electric gates along the Chicago Area Waterway System, which emit a low-level current that the fish won’t pass through, are the best defense against these now infamous invasive fish. Known for their acrobatic leaps out of the water, these carp are seen as a direct threat to the $7 billion commercial and sport fishing industries in the lake. The ways they upset local food chains and ecosystems could have far more disastrous cascading effects as well.

Ann Runstrom, left, Heidi Keuler, and Scott Yess, right, of the U.S. Fish and Wildlife Services show nets with stunned gizzard shad and a common carp as they work with members of the Illinois Department of Natural Resources using gill nets and electrofishing devices to search for Asian carp in the Chicago Sanitary and Shipping Canal in 2010 in Cicero, Ill (AP Photo/M. Spencer Green).

254: The number of “aquatic nuisance species” that the Army Corps' report found in the Mississippi Basin and the Great Lakes. The team narrowed this down to a list of 35 species posing a significant risk, identifying 13 as the “target species” for the study. These include the bighead carp and silver carp, which are likely to enter the Great Lakes, and the bloody red shrimp, fishhook waterflea, and grass kelp, at risk for entering the Mississippi Basin. Matt Doss, the policy director for the Great Lakes Commission, says that looking beyond the Asian carp is an important part of understanding the big picture behind why $18 billion — if that’s a realistic figure — may be worthwhile. “We’re already spending, both in the Great Lakes and in the nation, hundreds of millions of dollars a year to deal with this,” he explains.

Less than 3 percent:  The small percentage of the region’s total transportation of goods and materials that takes place on its waterways, according to the Great Lakes Commission’s report. There are two conclusions that can be taken from this. First, closing the canal and cutting off water access from the Great Lakes to the Mississippi Basin through a physical barrier would have pretty minimal impact on shipping. Second, as the “Restoring the Divide” report argues, these changes could be an opportunity. Finding new workarounds and improving the transit infrastructure along the canal — while improving strategies to fight invasive species — could actually increase this proportion and reduce congestion on area highways and rail lines.

A rendering of how a hydrologic separation along the Calumet River could still allow for shipping along the Chicago Area Waterway System, from the Great Lakes Commission's Restoring the Natural Divide report (Courtesy HDR, Inc.).

1.5 inches: Even this small level of precipitation over a two-hour period can be too much for Chicago’s current drainage system to deal with, leading to flooding of basements and floodplains. Separating the two water systems without any other adjustments would make this potential for flooding even worse, and the accompanying infrastructure improvements are part of the reason that the costs for the Army Corps’ $18 billion, 25-year alternative added up to so much. This most-expensive plan, which cuts off the two systems with a series of barriers at Lake Michigan, includes two new reservoirs and storage tunnels to deal with flooding, but this huge potential indicates the region has a big problem regardless of what happens with the canal.

$9.54 billion: This is the estimated cost of the most expensive plan that came out of the Great Lakes Commission and the Great Lakes and St. Lawrence Cities Initiative’s “Restoring the Natural Divide” report. Like the Army Corps’ more recent estimate, this is the assumed cost for creating several barriers near the Lake Michigan entrance to the waterway system.

So why is it half the price tag? The Army Corps’ estimate takes into account all sorts of changes — of flood management, and water treatment in particular — that Doss says would likely have to be made no matter what. The environmental group American Rivers has named the Chicago River one of America’s ten “most endangered rivers,” and over the last few years the national and Illinois offices of the Environmental Protection Agency have begun considering far higher standards for the waste that Chicago currently dumps downriver. As Doss explains, the wastewater plants that are included in the costs of the Army Corps’ plans should probably be built anyways. “One hundred years ago, we didn’t have the same kind of technology we have today to treat wastewater. Now we have those technologies,” Doss says. “Other cities around the Great Lakes are able to treat their wastewater that’s acceptable to discharge to the Great Lakes. There’s no technical reason why Chicago can’t do that.”

$18 billion is a hefty sum, and, even more worrying, 25 years is a long time to wait when Asian carp are already knocking on the gates of Lake Michigan. But the results of this extensive, seven-year study make a compelling case for moving forward now. Three years ago, a federal appeals court ruled that the Great Lakes states couldn't force an immediate closure of the locks on Chicago area waterways. But that didn't mean something shouldn't be done. In fact, the decision continued, “We need not wait to see fish being pulled from the mouth of the Chicago River every day before concluding that a threat of a nuisance exists.”

Top Image: Downtown Chicago as seen from the river (Christoffer Hansen Vika/

About the Author

Most Popular

  1. photo: Police line up outside the White House in Washington, D.C. as protests against the killing of George Floyd continue.

    America’s Cities Were Designed to Oppress

    Architects and planners have an obligation to protect health, safety and welfare through the spaces we design. As the George Floyd protests reveal, we’ve failed.

  2. A photo of a police officer in El Paso, Texas.

    What New Research Says About Race and Police Shootings

    Two new studies have revived the long-running debate over how police respond to white criminal suspects versus African Americans.

  3. A participant holding a Defund Police sign at the protest in Brooklyn.

    To Defund the Police, Activists Rewrote City Budgets

    As national protesters call for defunding police, a movement for anti-racist “people’s budgets” is spreading from LA to Nashville to Grand Rapids.

  4. Equity

    What Happened to Crime in Camden?

    Often ranked as one of the deadliest cities in America, Camden, New Jersey, ended 2017 with its lowest homicide rate since the 1980s.

  5. Four New York City police officers arresting a man.

    The Price of Defunding the Police

    A new report fleshes out the controversial demand to cut police department budgets and reallocate those funds into healthcare, housing, jobs, and schools. Will that make communities of color safer?