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On May 17, Milwaukee County experienced a county-wide rainfall depths that ranged from four to five inches. It rained hard that day and continued for several days.
This amount of rainfall overwhelmed the Milwaukee Metropolitan Sewerage District (MMSD) sewer system and the local municipal systems. Everything was full. MMSD’s two water reclamation facilities can efficiently clean about 630 million gallons of water per day and the deep tunnels can store up to 521 million gallons.
Many find it hard to visualize this amount of water. We know that one inch of rain spread over the MMSD service area is approximately 7.1 billion gallons of water. For the May event, this translates to 28 to 35 billion gallons of water hitting the ground.
Living here in snow country, another way to visualize this storm event is to think about what it would have been if it had fallen in the winter as snow. The baseline ratio is that one inch of rain equals 10 inches of snow. If the May rainstorm were snow, we would have had 40 to 50 inches or approximately four feet of snow.
Imagine four feet of snow. Streets would be impassable, and schools and businesses would be closed. The region would have been shut down for days, and our backs would be sore from shoveling.
While we work to further reduce sewer overflows, we need to do more, and we need you to do your part. Help us reduce water pollution from sewer overflows by joining the Water Drop Alert™. By using less water, you can help reduce the amount of sewage that might end up in the environment if there is an overflow.
Just like when it snows four feet or when we have four to five inches of rain, these storms take their toll, and we strive to recover as fast as possible. Let's just hope we don’t have either soon.
Kevin L. Shafer, P.E.
Executive Director - Milwaukee Metropolitan Sewerage District
Join our Blue Notes email list to receive quarterly MMSD updates and news.
Receive Water Drop Alert text messages when heavy rain threatens the area. When a Water Drop Alert has been issued, a reminder is sent to use less water.
What do you do when an alert is issued?
MMSD cleans billions of gallons of wastewater every year, safeguarding natural resources and protecting public health for 28 communities in southeastern Wisconsin. We treat a range of wastewater sources from industrial to surface runoff and whatever water you send down the drain at home, work, school, or church. Learn about the various aspects of wastewater treatment.
Green infrastructure captures, absorbs or stores rain and melting snow, taking on numerous shapes and sizes from 55-gallon rain barrels to trees and porous pavers for parking lots, driveways and sidewalks. You can see green roofs on buildings or bioswales along city streets.