Milwaukee Metropolitan Sewerage District
Press Release

Storm Update – September 11 & 12, 2022


By - Sep 16th, 2022 12:35 pm

(Milwaukee, WI) – Record rainfall drenched the Milwaukee area September 11 and 12, 2022, resulting in localized flooding, property damage, and overflows from local and regional sewer systems to reduce the risk of basement backups.

The National Weather Service (NWS) reported 4.78 inches of rain in Milwaukee on September 11, 2022. An additional one to two inches fell on September 12, 2022, raising two-day totals to 5-inches to 7-inches of rain (See map below).

One inch of rain on MMSD’s service area equals 7.1 billion gallons of water

To improve regional wastewater infrastructure and reduce the risk of flooding, the Milwaukee Metropolitan Sewerage District (MMSD) expects to invest more than $2 billion in projects over the next decade.

That includes funding Greenseams® property acquisitions to permanently protect wetlands so they can safely store rainwater and snowmelt, helping reduce the risk of damage from flooding. The program is now safeguarding more than 5,000 acres of land (nearly eight-square miles) in the Milwaukee, Menomonee, Root, and Oak Creek watersheds that can capture and naturally store 2.8 billion gallons of water. The Greenseams® program has planted more than 117,000 native trees and restored about 1,000 acres of land to woodland, prairie, and wetland cover.

MMSD is reporting the following information to the Wisconsin Department of Natural Resources regarding sewer overflows that resulted from heavy rain on Sept. 11 and 12.

COMBINED SEWER OVERFLOW:                             751 million gallons

SEPARATE SEWER OVERFLOWS:                           Volume                       Duration

S. Howell Ave, South of Grange – Wilson Park Creek         125,000 gallons                 3.25 hours
S. 35th & Manitoba – Kinnickinnic River                                   1.6 million gallons            2.68 hours
S. Kinnikinic & St Francis – Lake Michigan                               295,000 gallons                 2.12 hours
N. River Rd. & W. Green Tree Rd. – Milwaukee River        2.9 million gallons            2.83 hours

TOTAL SSO      4.93 million gallons

Separate sewer overflows also occurred in local sewer systems in Brookfield, Cudahy, Elm Grove, and Menomonee Falls.

Image from MMSD.

Image from MMSD.

Image from MMSD.

Image from MMSD.

MMSD is a regional government agency that provides water reclamation and flood management services for about 1.1 million people in 28 communities in the Greater Milwaukee Area. It serves 411 square miles that cover all, or segments of, six watersheds. The District is a regional government agency established by state law. Learn more at

NOTE: This press release was submitted to Urban Milwaukee and was not written by an Urban Milwaukee writer. While it is believed to be reliable, Urban Milwaukee does not guarantee its accuracy or completeness.

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