Aug 16, 2021

380 Million Gallons of Untreated Wastewater Flows Into Milwaukee Area Rivers & Lake Michigan

Heavy rains led to an overflow of Milwaukee, Wisconsin’s combined sewer system on Aug. 15.

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Heavy rains led to an overflow of Milwaukee, Wisconsin’s combined sewer system on Aug. 15.

This resulted in millions of gallons of untreated water flowing into local waterways, reported Milwaukee Journal Sentinel. 

According to a report from the Milwaukee Metropolitan Sewerage District (MMSD), about 380 million gallons overflowed out of the sewer system released Aug. 13. The untreated water containing sewage was then released into the Menomonee, Kinnickinnic and Milwaukee Rivers, Lincoln Creek and Lake Michigan, reported Milwaukee Journal Sentinel. 

The storm on Aug. 6 triggered the overflow, which ended at 11 p.m. Aug. 10. 

The storms on Aug. 7 and 8 were more intense, however. Between Aug. 6 and Aug. 11, approximately 7 inches of rain fell in some areas of Milwaukee.

As a result, operators at Jones Island sewage treatment plant diverted some wastewater around the full treatment process from 3 a.m. on Aug. 8 until 2 p.m.. 16.5 million gallons of wastewater were pumped out of the deep tunnel to the plant's disinfection facility before being discharged to the lake. 

The current estimate of the overflow volume is 380 million gallons, which includes seven combined sewer overflows not tributary to the ISS. MMSD issued a water drop alert as well. According to the report, the District will continue monitoring sewer overflows and report any revisions. 

Some water was kept from entering the system at all through green infrastructure, according to district director Kevin Shafer, reported Milwaukee Journal Sentinel.

Green infrastructure has helped to keep about 38 million gallons of water out of the system, in addition to any rain caught in rain barrels across the city. The district has invested about $400 million so far in flood management programs. 

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