Chicago Wastewater a Potential Health Threat?

Chicago needs to begin disinfecting its wastewater before discharging it into public waterways, a practice that currently poses a threat to public health, according to a new report from the Alliance for the Great Lakes.

The report, “Protecting Public Health, Caring for Chicago’s Waters: An Agenda for Action,” notes that Chicago is one of only four large cities in the U.S. that don’t disinfect their wastewater. The report also pointed out that the three other cities — Memphis, St. Louis and Kansas City, Missouri — all plan to begin disinfecting wastewater in the near future.

Other major cities in the U.S. all disinfect their wastewater to kill any viruses, bacteria or other pathogens that could threaten public health after that water is released back into local waterways.

“While disinfection will not keep beach closings and swimming bans from occurring, it will help reduce the influx of these harmful pathogens into our environment,” said Jonah Smith, water quality project manager for the Alliance and the primary author of the report. “To protect the lakefront, we need to protect the river as well. This means storm water management and disinfection.”

The potential threat to public health comes when heavy rainstorms overwhelm the Metropolitan Water Reclamation District (MWRD) of Greater Chicago’s ability to manage the flow of the Chicago River. Engineers reversed the river’s flow in 1900 to prevent sewage entering the river from flowing into Lake Michigan, the city’s source of drinking water. However, during heavy rains, the MWRD must allow the river to flow back into the lake. When that occurs, bacteria and other pathogens can enter the lake, prompting authorities to close beaches and enact swimming bans.

Lake Michigan provides drinking water for about 10 million people; the entire Great Lakes system provides water for up to 40 million people throughout the region.

Alliance chairman Dale Bryson said the MWRD has historically “viewed the Chicago River system as a waste conduit.”

“We need a new vision, one that treats water as vital for recreation and life itself,” Bryson said. “Getting MWRD to disinfect its waste is the first step toward moving ahead with the new vision for Chicago’s waterways.”

According to the Alliance report, Chicago could disinfect its wastewater for as little as $8.52 per person per year, using ultraviolet light, ozone or chlorination/dechlorination systems.

The Alliance report was produced in collaboration with the Environmental Law & Policy Center, the Natural Resources Defense Council, Prairie Rivers Network and the Sierra Club

Alliance for the Great Lakes, “Chicago Must Step Up Sewage Treatment; Stop Risking Public Health.” URL: (