Sanitary sewer overflows reported in wake of overnight storm

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MADISON, WIS. – Madison Metropolitan Sewerage District crews are responding to numerous reports of sanitary sewer overflows Tuesday in the wake of Monday evening’s storm.

Although the District’s regional wastewater collection system operates separately from municipal storm water sewers, heavy rains infiltrate the wastewater system through multiple ways including basement floor drains.

In many areas, flooding and basement backups are resulting from excess stormwater. Sanitary backups are currently being reported in areas of Fitchburg, on Madison’s far West Side near the Madison Marriott West and in the Spring Harbor neighborhood.

Residents experiencing flooding including basements backups should:

  • Treat all floodwaters as contaminated.
  • Be aware of the risk of electrocution. Do not touch electrical equipment if it is wet or if you are standing in water. If it is safe to do so, turn off the electricity to prevent electric shock.
  • Avoid wading in floodwater, which can contain dangerous debris and be contaminated.
  • Report missing manhole covers, water flowing across roads or entering your home through sanitary connections. Contact your local municipality or sanitary District with this information. A list can be found at

Through Tuesday morning, the District’s Nine Springs Wastewater Treatment plant recorded peak flow at a rate of 155 million gallons per day, compared with an average daily flow of 42 million gallons. More than two dozen District crew members remain out monitoring the more than 141 miles of District- owned pipe.

Through the night, the District’s 18 major pumping stations performed as intended to handle extreme weather, however, as water continued to enter the system Tuesday, the volume in some areas of the system exceeded capacity. Due to continued high waters and volume in various areas of the collection system, residents are encouraged to take steps to reduce water use for the day until system flows return to closer to normal.

“Our crews continue to assess the situation and we will continue to provide updates as more information becomes available,” said Michael Mucha, the District’s chief engineer and director. “We appreciate the partnership with our customer communities in addressing the challenges associated with the flooding.”

District staff members have notified the Wisconsin Department of Natural Resources and Public Health Madison and Dane County. For more information about Madison Metropolitan Sewerage District’s regional collection system and the Nine Springs Wastewater Treatment Plant, visit