Summary: Over the past week, extreme precipitation events in areas around the country caused severe flash flooding, wreaking havoc in local communities, and leading to the disruption of infrastructure services. With a warmer atmosphere creating more intense rainfall in a shorter period of time, water and wastewater utilities are encouraged to re-assess their flood risk and prepare for more intense extreme weather.
Analyst Note: On August 10, the National Weather Service issued multiple Flash Flood Warnings for southeastern Wisconsin due to slow-moving storms producing significant rainfall. Some areas reported accumulation exceeding 10 inches, with some areas reporting nearly 15 inches of rain. Flood waters disrupted operations at Mitchell Airport, caused minor power outages, and led to road disruptions. Multiple dams in Waukesha County are currently at or nearing outflow capacity.
In the Chattanooga area, of Tennessee, heavy rainfall created deadly flash flooding with some areas experiencing over six inches of rain falling in a single day. The flooding forced the closure of an interstate highway and tragically led to at least four fatalities. Additionally, in Connecticut severe thunderstorms created intense rainfall leading to flash flooding and widespread power outages. Lastly, in Eastern Illinois, a fast-moving storm triggered flash flooding and infrastructure impacts. Streets flooded, power lines fell, and a temporary outage affected the local 911 center.
Flash flood warning across the U.S. have reached a near record high this year. The National Weather Service had already issued more than 3,600 flash flood warnings across the U.S. in 2025 by late July, close to its average for an entire year.
Original Sources:
- https://www.fox6now.com/news/waukesha-county-state-emergency-declared-over-flooding
- https://apnews.com/article/tennessee-flooding-deaths-chattanooga-child-storms-f809a7ecd6525b2b07f56761708a65d2
- https://theconversation.com/why-2025-became-the-summer-of-flash-flooding-in-america-261650
Additional Reading:
Mitigation Recommendations:
- EPA - Build Flood Resilience at Your Water and Wastewater Utility
- EPA - Power Resilience for the Water and Wastewater Sector
Related WaterISAC PIRs: 16, 17, & 18
