The lowdown on the Chicago wastewater system
From Lake Michigan to the faucets of Chicago residents, and 120 surrounding suburbs that share the same regional rainwater and sewage system, wastewater makes its way through underground sewer drains to a wastewater treatment plant. Once filtered, the water will flow into the nearest riverway, eventually ending up in the Gulf of Mexico.
In the event of heavy rain or rapid snow melt, the filtration system can’t operate at a pace quick enough to keep up with the input, so pipes filled with untreated wastewater are allowed to overflow and dump directly into the Chicago River system.
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What's in that water?
When rainwater hits the pavement, it can pick up pollutants like oil, salt and litter on the way into the drain. Chemicals used on lawns, including fertilizers and pesticides, can also flow into the drains during heavy rains. From home, raw sewage and pharmaceuticals combine with the previously mentioned pollutants on their way to the wastewater treatment plant. While wastewater treatment plants can rid the water of most of these compounds, salts, pharmaceuticals and nitrogenous wastes remain, threatening the health of the river and the bodies of water it flows into.
For the Chicagoland region, wastewater combines with the Illinois River which flows into the Mississippi River and eventually out to the Gulf of Mexico. For almost all other Great Lake adjacent cities, the water flows into the lakes and then out through the St. Lawrence Seaway. As the elements in the sewage water break down, it promotes algae growth and depletes the oxygen in the water, which results in what is called a dead zone or hypoxic zone.
Potential Impacts on wildlife
Shedd’s Freshwater Research Biologist Austin Happel has seen oxygen depletion firsthand in a Chicago stream. In June 2021, Happel’s team surveyed and collected data at Bubbly Creek after a few days of heavy rain when a nearby pumping station had turned on to remove untreated waste and stormwater to reduce flooding.
“Our team went a day after the station turned off, and there was no life in the water,” Happel said. “We found a lot of trash, and the water had no oxygen at all, which is not normal. It took about two weeks to start seeing fish in that system again.”
See the connections
Although someone in the Midwest might feel disconnected from the ocean, the water in the Great Lakes, rivers and streams in our own backyards are headed to the sea. How you use water at home absolutely impacts the greater system. Similarly, the individual actions we take in our own lives to make a difference for the planet add up and work in tandem with change being made at higher levels.
What can you do to help keep waterways clean?
No matter where you live, here are some helpful tips from the Friends of the Chicago River to conserve water and help prevent overflow and water contamination.
- Reduce your shower time: A 10-minute shower can use as much as 40 gallons per minute. Depending on your showerhead, reducing your shower by three minutes can save between 8 and 22 gallons of water.
- Turn off the faucet: Turn off the faucet while brushing your teeth, doing dishes, washing your face or cleaning. Don't let the faucet run while cleaning vegetables. Put a jug of water in your refrigerator rather than letting the water run to get a cold drink.
- Fix your faucet: A faucet that leaks 60 drops per minute will waste 192 gallons per month or 2,304 gallons per year.
- Delay laundry: Delaying laundry on a rainy day will reduce the amount of soapy water that might end up in the river.
- Dish washing machine: Delay dish washing. But if you must, use a dishwasher if you have one. Running a full dishwasher requires about 20 gallons of water compared to 40 gallons if you washed the same number of dishes by hand.
- Flush less: Each flush can use between 1.6 to 5 gallons of water. Replace leaky toilets. Products bearing the water-sense label can save nearly 13,000 gallons of water per year. Don't use the toilet as a wastebasket. It's estimated 75% of indoor water use is in the bathroom and a quarter of that is through toilets.
- Remove downspouts from storm sewer: Install rain barrels to capture water from downspouts and store for later use. A downspout can dump as much as 12 gallons per minute into the sewer system.
- Natural landscaping: Use native vegetation as opposed to turf grass. Native plants have root systems that extend down to more than 10 feet. In contrast, the root zone of turf grass typically extends only about 3 to 10inches, according to the city's department of water management.
- Permeable paving: Use paving blocks or grids, rather than asphalt or concrete, to reduce runoff into the sewer system.
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