The Milwaukee Metropolitan Sewerage District has asked residents to cut water use to reduce the risk of a combined sewer overflow ahead of heavy rains expected to sweep into the Milwaukee area later this evening.

The sewerage district is urging residents to take shorter showers, save laundry and dishes for another day, and empty rain barrels regularly. The sewerage district serves 1.1 million customers in 28 communities in the greater Milwaukee area.

The National Weather Service also has issued a beach hazard statement for Thursday, advising swimmers to avoid Lake Michigan as waves could reach six feet. There is also a risk off rip currents.

Milwaukee has a combined sewage system in which both stormwater and wastewater from homes and businesses flow through the same pipes before it is treated. 

If heavy rains cause the water reclamation facilities and deep tunnels to fill to capacity, the sewerage district must discharge untreated water into Milwaukee’s three rivers and Lake Michigan to prevent wastewater from backing up into homes and businesses.

When a combined sewer overflow does occur, most of that water is rainwater rushing out as soon as it enters the system. However, there is a risk of bacteria impacting local waterways, like Lake Michigan.

Even though Milwaukee residents have seen frequently soggy conditions this spring and summer, there has only been one overflow this year. That overflow occurred in early April, with 357 million gallons of untreated wastewater released into local rivers and Lake Michigan. 

Subscribing to water drop alerts can help everyone know when to limit water use as well as when an overflow has occurred. Residents can receive a water drop alert by texting WATERDROP to 414-296-4422.

More: Rain has pummeled Milwaukee so far this spring. Why haven’t there been more sewer overflows?

More: Milwaukee’s rivers were once open sewers to Lake Michigan. Here’s how they’re being cleaned up.

Caitlin Looby is a Report for America corps member who writes about the environment and the Great Lakes. Reach her at clooby@gannett.com or follow her on X @caitlooby.