MMSD Storm Update Aug 9-10, 2025

08/15/25 03:15:pm

The Milwaukee Metropolitan Sewerage District (MMSD) is reporting the following information (see 5-day letter) to the Wisconsin Department of Natural Resources regarding sewer overflows that occurred due to historic rainfall and flooding on August 9 through August 10, 2025.

Since 1995, MMSD has designed and constructed $585 million in flood management projects, including Lincoln Creek, County Grounds, Hart Park, Valley Park, and Pulaski Park, to name a few. All those projects provided levels of protection during the devastating storms that just occurred. Without those projects, damage in the region would have been much worse. MMSD has an additional $712 million in future flood management projects to get done, with significant work needed in the Kinnickinnic River Watershed, where there are 660 structures at high risk for flooding.

5-Day Letter to WNDR

Greater Milwaukee Rain Gauge Totals August 9 to 10, 2025

MMSD Greater Milwaukee rain gauage data from August 9 to 12, 2025

2025 MMSD VOLUME TREATED

Gallons Treated: 47,985,000,000

Gallons Overflowed: 5,140,010,600

Total Gallons: 53,125,010,600

MMSD % Treated: 90.32%

View Water Reclamation Facilities
Current Capacity

Record rainfall in the Greater Milwaukee area on August 9 and 10, 2025, resulted in life-threatening flash flooding, property damage, and overflows from local and regional sewer systems. MMSD received over 1,100 reports of water backing up into basements.

According to the MMSD area-wide rain gauges (see map below), 14 areas received seven inches or more of rain in 24 hours. To illustrate the scale of this event, one inch of rain across our service area is equivalent to 7.1 billion gallons of water.

Overflow Volume:

8/9/25 - Combined Sewer Overflow and Sanitary Sewer Overflow: 5.14 billion gallons

One inch of rain in MMSD's service area equals 7.1 billion gallons of water.

To view a map of the impacted waters from the sewer overflow in the Greater Milwaukee area.

Do You Have Standing Water in Your Basement?

If you have standing water in your basement, DO NOT go into the basement! Electricity + Water = Danger.

Wait for the water to drain out of the basement before entering. Or, call a qualified electrician to disconnect the power before you enter a flooded basement.

Call your municipal public works department to report local flooding, and call your homeowners/renters insurance agent.

Please fill out the "Report a Basement" form to help track flooding in our area, which is shared with the 29 municipalities MMSD serves.

Report a Wet Basement

Flash Flood Safety

Stay out of floodwater — it may have sewage, chemicals, or trash. Never walk or drive through floodwater. Wear boots and gloves for cleanup, and wash your hands after.

Food Safety After Flooding. Throw away any food, drinks, or medicine that has come into contact with floodwater. Toss food in packages that are wet or damaged. Wash and sanitize dishes, utensils, and counters that came into contact with floodwater.

What to do if you have property damage

Report all property damage from flooding, lightning, or extreme wind from the storm to 2-1-1.
- You can call 2-1-1 to report damage over the phone.
- You can fill out a form online at 211wisconsin.communityos.org/damage-report to directly submit a damage report.

Looking for flood resources and guidance?

Please visit Milwaukee County website for up-to-date information.

Additional Flooding Resources:

IMPORTANT! Water in the Basement can be dangerous

Do not go into a basement with standing water. Electricity + Water = Danger.
Call your municipal public works department to report the problem. If your municipality is unable to help you, call MMSD at (414) 272-5100 or report a wet basement.
Call your homeowners/renters insurance agent.
Wait for the water to drain out of the basement before entering. Or, call a qualified electrician to disconnect the power before you enter a flooded basement.

Text: WATERDROP to 414-296-4422 for Española texto GOTADEAGUA a 414-296-4422

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?

Hold off on washing dishes and laundry
Take a shorter shower
Empty your rain barrel

Heavy rains resulting in dangerous Milwaukee area Rivers

Heavy Rains = Dangerous Rivers

Please be safe around our concrete-lined rivers. STAY OUT of the concrete-lined channel since the water is fast-moving and the concrete is slippery. Call 911 if someone is in danger. We need your help in keeping our community safe.