A deluge of rain led to a sewer overflow Sunday night and continued into Monday morning as rain continued to fall throughout the Milwaukee area.
The overflow started at 11:15 pm Sunday night and was ongoing as of 9 am Monday, according to Bill Graffin, the Milwaukee Metro Sewerage District’s public information manager.
Some areas of the MMSD service area had received nearly 7.5 inches of rainfall over the course of Sunday and Monday, prompting the Jones Island facility to release water after reaching its capacity.
One inch of rain in the Milwaukee area equates to about 7.1 billion gallons of water that rush into the combined sewer system.
Sewer overflows prevent sewage backups
MMSD has the ability to allow overflows to happen in order to prevent sewage backups into homes and businesses across the area. Overflows are used after the deep tunnel fills during heavy rain events, and more water is flowing into the treatment plants than can be processed.
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Although there is a risk of untreated sewage being released into water bodies during overflow events, most of the water released — over 90% — is the rainwater flowing out of the system, as soon as it rushes in.
This is the first overflow of the year for MMSD, one of six allowed annually by the Department of Natural Resources under the district’s state discharge permit. In 2021 there were two overflows — one in August that released nearly 400 million gallons of water, and another in October which released about 10,000 gallons, according to MMSD.
Milwaukee residents urged to ease water usage
In a bid to lessen the amount of water being released into Milwaukee water bodies, MMSD issued a water drop alert Sunday night as well, asking residents to use less water in their homes. The department recommends saving laundry and dishes for another day, taking shorter showers and ensuring there is enough room in your rain barrel before heavy weather events.
Laura Schulte can be reached at email@example.com and on Twitter at @SchulteLaura.