Aging Iowa sirens generally don't signal flash floods
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This is among the first sirens in a new Des Moines warning system that will be completed in the coming months. Photo: Courtesy of the city of Des Moines
Iowa has a patchwork of outdoor emergency siren systems that are typically not used for flash flood warnings, local and state officials tell Axios.
Why it matters: The recent floods that killed over 130 people in Central Texas have heightened concerns across the U.S. that many communities lack reliable warning systems.
State of play: Iowa has struggled with outdated warning systems for years, some dating back to the Cold War era, when they would have been used to warn of a nuclear attack, a 2012 Des Moines Register investigation found.
- There are still no statewide criteria for their use, with guidelines for sounding sirens varying by local jurisdiction, according to the Iowa Department of Homeland Security and Emergency Management (HSEMD).
Zoom in: In Polk County, nearly 165 sirens — some over 25 years old — cover most urban areas but those in rural regions remain sparse, according to data and maps obtained by Axios.
- They are only used for tornado and severe thunderstorm warnings with winds over 70 mph.
Context: Using outdoor sirens for other warnings, like flash floods, risks causing confusion because people might not distinguish the specific threat without additional context, Polk County Emergency Management Agency (EMA) director A.J. Mumm tells Axios.
Reality check: Even if the sirens were used for flood warnings, they may not provide much extra protection.
- Weather models are improving, but right now it's impossible to make site-specific warnings because it's difficult to anticipate exactly where a flash flood will strike, Witold Krajewski, an environmental engineer at the University of Iowa, told the Washington Post.
What they're saying: Outdoor sirens can be helpful for broad alerts, but their limitations in range, clarity, and specificity make them "a last resort" compared to modern, precise and widely accessible alternatives like wireless emergency alerts, weather radios and app-based notifications, Mumm said.
- HSEMD recommends that people proactively plan for emergencies and use Alert Iowa, a system employed by 92 of Iowa's 99 counties that provides text, email and phone alerts for emergencies such as floods, fires and tornadoes, spokesperson Allie Bright tells Axios.
The intrigue: Some local governments in Iowa are moving away from outdoor warning sirens altogether, most recently in Clinton County.
What's next: Des Moines will complete the installation of a new $1.7 million severe weather warning system in the coming months, replacing one that's more than 20 years old.
- That system follows Polk County EMA guidelines and will not be used for flash flood warnings, police Sgt. Paul Parizek tells Axios.