Combined Sewer Overflow in Ingham County

Written by Mike Smalligan, CAFE Board member, Cherry Hill resident & Forester

When it rains in Lansing, your toilet might flush straight into the Grand River sending your untreated poop downstream to Grand Rapids and Lake Michigan. Large rain events overwhelm our sewage treatment plant because 30% of Lansing’s storm drains have not been separated from sewer drains. The City of Lansing has been working to fix “combined sewer overflow” (CSO) since 1993. Lansing Public Works director Andy Kilpatrick reports the city has “separated around 70% of the area that was served by combined sewers.”

Andy explains, “During dry weather, all of the combined flow goes to the wastewater treatment plant, so the storm sewer flow gets treated as well. Dry weather flows at the plant are around 12-14 Million Gallons Per Day (MGD). During wet weather events, flows can peak at up to 100 MGD.”

Unfortunately, the work to separate Lansing’s combined sewer overflow will not be complete until 2040. The $300 million needed for future CSO projects is funded by revenue from water utility ratepayers. Funding is adequate to separate the storm and sewer systems, but CSO work is complicated because many infrastructure projects are interconnected. CSO work is not easily accelerated because funding is limited for road repairs and BWL watermain replacement which are done at the same time as sewer separation. A map of upcoming CSO projects is at LansingMi.gov/513/Combined-Sewer-Overflow-CSO.

So how bad is this CSO problem? Let’s review some data for the first six months of 2025 to understand the magnitude of combined sewer overflow in Lansing. Municipal water utilities report combined sewer overflow events to Michigan Department of Environment, Great Lakes and Energy (EGLE). Those data are available to the public through EGLE’s MiEnviro Portal at MiEnviro.michigan.gov/ncore/external/overflow/list.

All data presented below were downloaded from EGLE’s MiEnviro Portal.

In the first six months of 2025, three cities in Ingham County dumped 92,205,780 gallons of sewage and stormwater into the Grand River and the Red Cedar River (which enters the Grand River in my Cherry Hill neighborhood). Lansing had 202 CSO events in the first half of 2025 with 95% of the volume polluting the Grand River, but East Lansing’s two sewage and stormwater discharge events were very large with one million gallons dumped on March 31 and three million gallons dumped on April 2 into the Red Cedar River.

The magnitude of the sewage and stormwater discharges is quite variable. The 22 largest events are just 11% of the events but account for 53% of the sewage and stormwater volume. About half of the events are mid-sized and account for 43% of the CSO volume. A little more than a third of the CSO events are small events that contribute relatively minor volumes of combined sewage and stormwater into the Grand River.

Ingham County had combined sewer overflows in five of the first six months of 2025. There were no CSO events in February, but the January event was on the last day of the month. Large rainfall events in winter may become more common because our changing climate is experiencing warmer weather in winters and higher intensity rainfall events. The worst date in the first half of 2025 was April 2 with 26,197,500 gallons of combined sewage and stormwater dumped into the Grand and Red Cedar rivers. The second worse date was January 31 with 19,531,000 gallons of sewage and stormwater dumped into the Grand River. Twelve other days in March, May and June had CSO events exceeding 1 million gallons of sewage and stormwater. Only six days had smaller CSO events with less than a million gallons of sewage and stormwater dumped into the Grand River. April was the worst month for CSO followed by May, January and June. April showers make for poopy rivers, not just spring flowers.

Combined sewer overflow can be related to environmental justice. Lansing has a big problem with CSO, but Detroit and all of Wayne County have much larger CSO discharges because of their massive infrastructure and chronic underinvestment in public works. For comparison, in the first half of 2025 Wayne County had 349 CSO events with 7.1 BILLION gallons of sewage and stormwater dumped into the Rouge and Detroit rivers. That is 77 times the CSO discharge as Ingham County! The cities of Monroe and Toledo get their drinking water from Lake Erie which is downstream from these huge CSO discharges in Wayne County.

Several communities in Wayne County charge stormwater fees to their residents to fund their CSO efforts. Some residents in Wayne County pay much more for separating the sewer leaving their home than for clean drinking water coming into their faucets. Monthly water bills in Wayne County can be hundreds of dollars, and some residents are not able to afford their water bills. Paying for the dirty water leaving a home is often more expensive than the clean water coming into the home.

CSO is a significant environmental problem in Michigan that requires continued investment in better public water works infrastructure.

What can YOU do about CSO?

1.      Ask the City of Lansing and BWL to finish CSO separation sooner than 2040.

2.      Learn about Lansing CSO at LansingMi.gov/513/Combined-Sewer-Overflow-CSO.

3.      Learn about statewide CSO at Michigan.gov/SewageDischarge.

4.      Become an EGLE Clean Water Ambassador.

5.      Replace your turfgrass with a raingarden to help reduce stormwater runoff.

6.      Plant trees in your yard and along the street to help reduce stormwater runoff.

7.      Vote for local, state and national policy makers who will protect clean water.