MMSD Blue Notes: August 2025 Historic Storm Teaches Lessons, Losses and Things We Need

What a terrible week this has been for so many people in the Milwaukee region. Devastation caused by the August 9 storm is everywhere. My heart pours out to all who are suffering. I hate to say it, but it could have been worse.

The National Weather Service reported that this is the second-largest storm in Milwaukee’s history, calling it a “1,000-year storm”. This designation might lead you to think that we won’t have this happen again for another 1,000 years, but that is not true. What it really means is that there is a 0.1% chance of this size storm occurring in any given year. It is rare.

The Milwaukee Metropolitan Sewerage District (MMSD) has been constructing flood management projects for the last 25 years. MMSD uses the “100-year” storm as the design criteria for these projects. This storm has a 1% chance of occurring in any given year. MMSD builds for the 100-year storm because these storms occur more frequently, and these projects are more cost-effective.

Ironically, MMSD started a study two years ago to predict the impacts of a 1,000-year storm. This study just completed and will provide a good baseline for future preparations for similar August 9 storms.

The question is how MMSD’s 100-year flood management projects performed when faced with a 1,000-year storm. Overall, the various projects helped reduce the devastation but did not eliminate it.

Another question to ask is how bad the devastation would have been if MMSD projects had not been built. We will try to answer this question in the future, but I think it is more important to hear what the community is saying. Below are some of the comments I have received.

Lisa Emmons from Valley Park Neighborhood, Milwaukee

“Many people in the neighborhood were saying thank God for MMSD yesterday. Yes, calling me and saying it! Many nervous moments but the levee held and we are all safe and sound! So much tragedy from the flooding all around us, we are so blessed.”

Amy Jensen

“Can’t imagine what this place would have looked like without all of your (and MMSD’s) work and long range planning over the past 27 years. I know you’re focused on the damage and cleanup right now but THANK YOU for protecting us all from what could have been so much worse!”

Kathy Ehley, former Wauwatosa Mayor and MMSD Commissioner

“I worked a Tosa Health Dept public event today and got a lot of positive comments about the work that Tosa and MMSD have done for infrastructure and flood mitigation over the years acknowledging the flooding over the weekend would have been far worse. The retention basins were full.”

And various comments from Reddit:

The Flood and Positive Role of MMSD in its Mitigation : r/milwaukee

“Based on all the data, it seems like this was one of if not the largest rain event in Southeast Wisconsin’s history.

It also seems likely that if MMSD hadn’t been preparing, building, and implementing green infrastructure for the last 30 years, it could have been much worse. In a world where Hart Park was still a neighborhood, the amount of catastrophic damage would have been disastrous. There have been some who’ve screamed that so much of what they’ve done was a waste, but in the light of all of this, that couldn’t be farther from the truth.

We need to recover. However, also I think we need to be clear-eyed that this type of deluge will become more common as Milwaukee becomes rainier due to climate change. The work of MMSD is important. And their projects must move more quickly.”

Thank you to all who provided this perspective, but, as the comment from Reddit says, these flood management projects must move more quickly. Specifically, MMSD is currently in the design and construction of flood management projects on the Kinnickinnic River, the most urbanized river in the State of Wisconsin, which has 660 homes and businesses in the floodplain. Construction of the Jackson Park flood management project will start full construction in 2028. The Wilson Park flood management project is being discussed with Milwaukee County Parks right now. We need to do all we can do to fund and accelerate these important projects.

Believe me, there will be another 1,000-year storm, we just don’t know when.