A recent New York Times article detailed Chicago’s precarious position as climate change worsens; the city was constructed atop a swamp, and its sewage system relies heavily on interactions between the Chicago River and Lake Michigan, whose water levels are now rising and falling to extremes: they climbed at a “stunning rate” in the summer of 2020, but also experienced record-breaking low levels each consecutive recent winter.

But Lake Michigan isn’t the only Great Lake reacting to increasingly erratic and extreme weather patterns — and Chicago is certainly not the only city coping with the effects (one Bloomberg article insists that, no, the Great Lakes region is not a “climate haven” as some have claimed). In 2020, the U.S. Army Corps of Engineers reported Lake Erie’s highest water level ever, at 52 inches above average. Climate change experts say that water levels have risen and fallen at unusual rates in all five of the Great Lakes in recent years, and, according to the EPA, the temperature in Ohio has risen by one degree in the past century.

Lake Erie water levels. Image courtesy of the US Army Corps of Engineers Detroit District.

A change in overall temperature means that the ice cover blanketing Lake Erie during Ohio’s winters is much smaller. A lack of cover causes more water to evaporate, drastically decreasing water levels. At the same time, polar vortexes are surging through the Midwest at a more frequent rate, increasing the ice cover for certain periods of time, slowing evaporation, and accelerating the water level for a time period. 

Both Lake Michigan and Lake Erie have seen the consequences of rising temperatures and dramatic oscillations. In 2013, Lake Michigan reached a low that left captains unable to unload freight ships, and experts feared the Lake might dip so low it would be unable to feed the Chicago River. In 2014, warmer water in Lake Erie increased algal bloom, prompting the City of Toledo to ban drinking and cooking with tap water. 

Brutally cold winters inspired by the destabilization of air around the North Pole — likely a result of climate change — sent blasts of arctic air, also known as a polar vortex, into the Great Lakes region. Those blasts drove lake levels to a high in 2020 and 2021, causing extreme flooding across Chicago and Toledo.

In Chicago, fluctuating water levels present an additional challenge because of the nature of the city’s sewage system. Like Toledo, Chicago is built atop a swamp. City planners put sewers on top of the streets, then built new roads on top of those sewers, hoisting the city upward. 

Then, sewage flowed into the Chicago River, which in turn flowed into Lake Michigan. At the end of the 19th century, city leaders reversed the direction of the river by constructing the Chicago Sanitary and Ship Canal and Harbor Lock, made of steel gates that separate lake and river water. Climate change threatens that reversal. 

If the lake level drops too low in relation to the Chicago River — which carries Chicago’s treated wastewater south — wastewater may begin flowing into the lake. Conversely, if lake levels are too high, the river and canal system will be overwhelmed, meaning that city employees must decide whether or not to open Harbor Lock. Either the city streets will flood with sewage, or polluted water will flow into Lake Michigan. Or both. 

Chicago’s Harbor Lock. Image courtesy of Alexander Klink.

Although Toledo holds a similar position between a river and a Great Lake and also atop a swamp, experts say the immediate danger posed by climate change is less severe. 

“The threat is more immediate for Lake Michigan,”  Dr. Jonathan Bossenbroek, professor of ecology at the University of Toledo, said. “Chicago was literally built on swampland, on a continental divide.”

Bossenbroek explained that although the greater Toledo area was built on a swamp as well, its natural topography protects it. The Maumee River was always located above the swamp, and “there was always a true river system,” he said. “The Chicago River was essentially created, and the Maumee River was there. It had a natural structure of floodplains for excess water in heavy storms.” 

Traditionally, Toledo has worked with a combined sewer system. During heavy storms, the system does tend to get overwhelmed, and the city, aligned with the Ohio EPA, has been working for years to reduce the amount of waste contaminating the waterways during heavy storms, according to Bossenbroek. The endeavor has primarily involved constructing tanks that can hold and redirect waste water. 

Patekka Pope Bannister, Commissioner of Plant Operations at the Department of Public Utilities for the City of Toledo, worked on the Toledo Waterways Initiative, a $527 million  combined sewer overflow program that separated storm sewers and sanitary sewers.

“At one point, what happens in Chicago was the practice here too, where you move all the water out to the river,” Bannister said. “That is no longer an acceptable practice. We developed these storage areas so that we have the capacity to store excess water in these huge storage facilities.”

Bannister says there is also a “wet weather” facility so that overflow water can be chemically treated in some cases. 

Still, the Maumee River has experienced increasingly overwhelmed sewage systems like Chicago’s on a regular basis due to climate change. Intense storms are more frequent as the temperature rises, and the Great Lakes Basin will see an increase of up to 40 extremely warm days due to climate change. 

Pope Bannister says that Toledo’s most pressing issue comes from the prevalence of these extreme storms — and the ecological imbalances that result. 

“We will have weather patterns in the winter where we have more and more extreme storms, but the ground is frozen and can’t absorb the water,” she said. “You get inches of rain, and we have to deal with the flooding and an increase in algal blooms.” Algal blooms are what rendered Toledo drinking water unsafe in 2014. 

Algae in northwest Ohio waterways.

Those blooms are exacerbated by climate change. 

“The problem is shallow, warm water,” Lawrence said. “Living organic organisms seek out energy, and that energy is heat. Data is showing that long term water temperatures in the Great Lakes, and particularly in the basins, are going up. And that means more algae.”

Nutrient balance studies have revealed that 89 percent of the Maumee River’s phosphorus comes from agricultural runoff, not raw sewage. So although blooms exacerbated by climate change pose a threat to the city’s drinking water, unlike Chicago, changing water levels are not likely to severely disrupt the sewage system in Toledo. 

Toledo also has man-made geography that protects its residents from the immediate threat of changing water levels. In 2020, when Lake Michigan reached its highest water level to date, entire beaches were submerged, and homes across the lake experienced flooding. The Chicago River runs straight through downtown Chicago, and office buildings are steps from the water. Not so much of Toledo’s infrastructure is built in such close proximity to the water.  

“Our risk of major damage to infrastructure is nothing compared to Chicago,” Bossenbroek said. 

Despite Chicago facing more severe problems in comparison, Lawrence says that Toledoans should still be wary of the fluctuating water levels. 

“It’s not quite as sensitive in and around Toledo itself, but different communities along Lake Erie have experienced flooding and erosion,” he said. “Changing water levels do make it hard to plan for and build waterside infrastructure. First you’re planning for high water levels, and then suddenly you’re worried about the impact of lower water levels.” 

While Toledo has not built extensively alongside the water, Bossenbroek wants the city to learn from Chicago’s experience and invest in safeguards for the future. 

“Right now, we don’t have a good handle on what will happen,” he said. “There’s a whole lot of unknowns. We have time. It’s all about figuring out where the excess water goes, when the lake level rises.”

The City of Toledo proposed a grant through the University of Michigan in 2014 that focuses on protecting properties “within and adjacent to the floodplain.” The proposal asked to identify public and private properties that have potential for stormwater storage, and offer mini grants to commercial property owners to bolster on-site stormwater management. 

In the meantime, Pope Bannister has been involved with a number of initiatives that help ensure clean drinking water for Toledoans. Toledo is currently executing a $5 million  capital improvement plan, and part of that tackles clean drinking water. At the end of June, the City of Toledo also concluded $50  million  of construction on an ozone facility, a project that intends to help slow the threat of algal blooms. 

Overall, Lawrence thinks that Toledo is at an advantage due to that infrastructure and because the city is neither at risk of drought nor of flooding due to sea level change. 

“As our winters get a little bit shorter and a little bit milder, we might be an attractive opportunity, and experience a reverse migration,” he said. “We may be an ideal place for people who want to escape areas that might be under threat from the environmental changes that are occuring nationwide.” 

With increased effort from the city to manage waste overflow and a population fairly removed from the water, Bossenbroek agrees.

“On the coasts, they don’t have enough water,” Bossenbroek said. “In Chicago, there’s too much water. For now, Toledo is positioned ideally to tackle climate change.” 


  1. Allowing a river to have access to floodplains during high water conditions is essential to buffering damaging impacts of those flows. The Toledo park lands along the river and its tributaries can help provide that function while at other times enabling access and enjoyment and critical habitat corridor for the whole natural system along the river.

    The phosphorus loading and algae problems are a separate issue completely. The highlighted recent investments in wet weather stormwater treatment and surge volume holding capacity in the sewage system are important to the health of the river and the people that depend on it. We all live downstream of one another when it rains.

    Toledo may not be perfectly insulated from the global climate changes but by taking care of our local ecosystem we can better ensure it will be there to protect and nourish us as we also do for it.

    Lake Erie waters would be a lot healthier if we still had the larger original amount of marsh lands along the shores. Those wetlands function like kidneys to take up dissolved excess nutrients which otherwise fuel the seasonal overload of (sometimes toxic) algae blooms. I would love to see even more frogtown habitat along Swan Creek nearer to downtown Toledo!


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