At the height of summer in mid-July, residents of Mattoon in central Illinois, were told they couldn’t use their tap water.
The water supply had been infiltrated by a tiny yet potent invader: cyanobacteria. The bacteria had multiplied rapidly in nearby Lake Paradise, which serves as the primary water source for the town of nearly 17,000. In a matter of days, cyanobacteria overwhelmed Mattoon’s municipal water system, sending toxins into the water supply and making it too hazardous to drink or cook with.
The city issued two separate Do Not Drink orders — which stayed in place for nearly eight days — forcing businesses to close or bring in water. And since toxins can’t be boiled away, it created an extra level of concern and confusion among residents, according to Mattoon Public Works Director Dave Clark.
“They were unsure what they could and couldn't do,” Clark said. A lot of them were like, ‘Can I wash my hair? Can I take a shower? How long is this going to last? And where do I get water that I can drink?’”
Though ingestion of contaminated water is considered the most likely to cause illness, showering and bathing with tainted water can also expose people to toxins, according to the U.S. Environmental Protection Agency.
The city of Mattoon distributed more than 80,000 gallons of drinking water to residents over a seven-day period at a local park and elementary school.
Waterways contain naturally-occurring bacteria and algae, which are an important part of aquatic ecosystems. But nutrient-rich runoff from farm fields, as well as cities and towns, can fuel the growth of these tiny organisms, creating what's known as harmful algal blooms. These blooms can contaminate water supplies, forcing municipal water systems to temporarily shut down and disrupting life for local residents.
In Mattoon, the bacterial bloom coincided with Bagelfest, the town’s 40th annual festival celebrating a local commercial bakery. Now owned by BIMBO, the bakery produces Lender’s and Thomas' Bagels and has longstanding ties to the community.
Though the live music, carnival rides and food trucks carried on, water for the festival had to be trucked in from out of town.
Food truck vendor Chris Walden, who sold lemon shake-ups and funnel cake at Bagelfest, picked up water in a nearby town. But he said the Do Not Drink orders affected his home and business, both of which are in Mattoon.
"So it's not just just our stand, but it's also our shop, where we store everything,” he said. “And then also our house too, as far as showering and water and everything."
Fertilizers feed algal blooms
Cyanobacteria like those that affected Mattoon produce neurotoxins, which can sicken and even kill people who drink contaminated water.
Repeated exposure can cause gastrointestinal symptoms such as vomiting and diarrhea, as well as damage to the liver, brain and other organs.
Reports of illness from people ingesting tap water tainted by these toxins seem to be rare. University of Michigan professor Gregory Dick’s research focuses on microorganisms and water quality. He said there are well-documented cases of people getting sick from swimming in lakes contaminated with algal bloom toxins, however.
“That is a relatively common occurrence,” said Dick. “So the health threats are real. And the other thing we know is that pets, and especially dogs, are particularly vulnerable to these harmful algal blooms. In fact, every year, dogs die from swimming in this water.”
Bacteria and algae are always present in lake and river water.
But they become a health hazard when they multiply into large blooms. These colonies feed on nutrients like nitrogen and phosphorus used to fertilize crops and lawns, along with animal waste from large livestock operations or sewers.
Robert Hirschfeld, director of water policy with the Illinois-based environmental group Prairie Rivers Network, said more and more farm chemicals have run off into lakes and streams over the years.
“This is a byproduct of our agricultural production system,” he said.
As humans have transformed the landscape, converting more land to farmland and using more fertilizers to grow crops, he added, excess nutrients are flowing into waterways and feeding algal blooms.
Hirschfeld’s organization supports laws that would require the farming sector to take a more active role in preventing erosion that spreads fertilizer chemicals into rivers and lakes.
“We think it’s long past time that we treat agriculture as the big boy industry that it is,” he said. “It’s a major, major industry in this country, and we need to pass laws and rules that require [them] to reduce their pollution.”
A costly issue
Mattoon is hardly the only city that’s dealt with the problem.
In 2023, an algal bloom in one of the reservoirs for Guthrie, Oklahoma, forced the city to quickly switch to an alternative water source.
Another massive bloom in Lake Erie prompted a three-day Do Not Drink advisory for more than 400,000 people served by Toledo, Ohio’s water system in 2014. A few weeks later, the same algal bloom led to warnings not to use water from private wells on the shoreline of Pelee Island, Lake Erie’s largest island located in Ontario, Canada.
The impact to residents when a toxic algal bloom affects their water supply is substantial, according to Dick, the University of Michigan professor. The 2014 Lake Erie bloom was especially disruptive for residents, he said.
“That affects not just people’s drinking water,” Dick said, “but their ability to take medicines, their ability to cook. So it really disrupted lives for residents, for businesses, for hospitals.”
After that crisis, Toledo installed sensors and carbon filtration to ensure its water supply is clean. Similarly, in August, the Mattoon City Council voted to invest in new measures to help protect its water system from algal blooms. The city will spend roughly $300,000 to spray algaecide to control algae blooms in both of its reservoirs and replace a broken water pump.
City Manager Kyle Gill said that eventually, they’ll need to dredge both reservoirs to get rid of fertilizer-laden silt.
“We’ll spend hundreds of thousands of dollars in the short term, but most of the long-term solutions are millions of dollars,” said Gill.
Such solutions will likely be needed in more towns and cities throughout the Midwest, said Dick, as algal blooms don’t appear to be slowing down.
“There is good evidence that these blooms are responding to climate change,” Dick said. “In the Great Lakes, we're seeing that the bloom season is getting longer as the waters get warmer. So it's still being scientifically debated in terms of just how much blooms are increasing. But it does seem that they're becoming more frequent and they're lasting longer.”
A growing body of research has found harmful algal blooms are occurring more often and in a broader range of places, in response to climate change and increased nutrient runoff.
Yet Keith Loftin, who studies algal blooms at the U.S. Geological Survey’s Kansas Water Science Center in Lawrence, said it’s difficult to know if the blooms are uniformly worsening across broad geographic scales.
“Many claim that blooms are becoming more frequent, greater in magnitude, duration and spatial extent,” said Loftin. “However, largely, we lack robust, consistently collected data sets throughout modern times to make large sweeping national and global statements.”
University of Wisconsin professor Todd Miller studies waterborne toxins and the microbial life that produces them.
He said the conditions to create harmful algal blooms are on the increase, even if the data are lacking to be sure harmful algal blooms overall are on the rise.
“We’re at the point now where around 70% of all water bodies in the United States are nutrient-rich, or what we call eutrophic,” Miller said. “So in that sense, we are seeing an increase across the nation in the number of water bodies that can support the formation of algal blooms.”
That may mean residents in more towns like Mattoon could experience disruption to water services in the future.
This story was produced in partnership with Harvest Public Media, a collaboration of public media newsrooms in the Midwest and Great Plains. It reports on food systems, agriculture and rural issues.
