Texas Flash Flooding — Could it Happen Here

If a major flash flood were to hit St. Charles County, Director of Emergency management Jani Albright says plans are in place. Albright manages many technologies that protect the public from weather events. That includes an array of 177 pole-mounted sirens which can blast out a loud, blaring warning note or broadcast verbal instructions such as evacuation orders.

"Once during a levee breach, we used two sirens in West Alton and Portage des Sioux to warn people to evacuate," Jani says. "We can use the sirens to put out a voice warning, telling people to get out."

Albright reminds people that the outdoor warning system is not designed to be heard indoors.

"Outdoor sirens will not ensure that people indoors will hear them," Albright says. That's the importance of the NOAA radio."

The NOAA weather radio, available in stores, sounds the alert whenever a severe weather event is forecast for the immediate region. Having such a radio at home or work is a crucial tool for public safety, Albright says.

Another tool St. Charles County has that could play a role in flash flooding comes through your cell phone. It's the Wireless Emergency Alert (WEA) system, a program offered by the Federal Emergency Management Agency to warn people in targeted areas. St. Charles County used it for the first time during the May 16 tornado that swept through our region.

"We used it when some straight-line winds knocked down a row of power poles on Highway N in Dardenne Prairie," Albright says. "It hit right when school was letting out, and there was so much traffic that we needed to tell people to stay away from the area."

In a flash flood, the WEA system could be used to send real-time alerts to people in harm's way. This would be received by the cell phones of people in a targeted area, and by the cell phones of anyone driving into it.

The Texas tragedy is unique, but several big flashfloods have hit St. Charles County:

• July 26, 2022: A line of thunderstorms dumped 2 inches of rain per hour. Some areas got 11 inches of rain. The watersheds of Spencer Creek, Dardenne Creek, and Belleau Creek flooded near Interstate 70 in St. Peters. Water covered roads and entered structures in Old Town St. Peters, and parts of I-70 were under water.
• May 25-26, 2008: Heavy rain flooded Peruque Creek. The rising waters covered Route 79 and Highways P and M. Dardenne Creek also flooded low-lying areas north of St. Peters near
  Route C.
• 1993, The Great Midwest Flood: Evacuation orders were issued for West Alton. An estimated 40% of the county had flooding.

Search and Rescue Teams Ready to Go

St. Charles County Emergency Management partners with emergency responders in other state and local organizations.

During a flash flood, a fleet of more than a dozen swiftwater rescue boats here could be deployed, according to Jeremey Hollrah, Deputy Chief of Special Operations and Logistics with the St. Charles County Ambulance District (SCCAD).

"When we're expecting a high volume of rain, we typically have units ready on standby with extra staff," Hollrah says. "We coordinate with the Weather Service and Emergency Management when that type of event is anticipated."

The ambulance district and the fire services have personnel trained for swiftwater rescue.

Crews in swiftwater suits with ropes and rescue equipment are trained to pull people from flooded cars, buildings and trees. They practice in local rivers, as well as the fast-flowing St. Francis River in southeast Missouri, and at Six Flags in the Thunder River ride.

"We practice different techniques on how to make access in swift water, and what are the appropriate angles of approach with the boat," Hollrah says.

Another important tool that could be used during flash flood is drones. Armed with thermal imaging and night vision, the drones are capable of seeing someone in need of help.

"They're rapidly deployable to give us an overhead view," Hollrah says.

Recently, a St. Charles County Police drone was able to spot a suspect who had jumped into a river after a police chase and disappeared into the night. The drone's thermal imaging spotted the heat signature of the man standing in the woods down river.

Planning and Zoning Safeguards in Place

St. Charles County Director of Community Development Michael Hurlbert says zoning laws here going back to the 1970s often prevent people from building additional structures in dangerous areas of flood plains, keeping population density lower in flood-prone areas.

"Our floodplain ordinances are in place to prevent development that could be hazardous to life and property," Hurlbert says. "There are also no campgrounds in St. Charles County in areas vulnerable to flash flooding."

The county does have some older developments that pre-date its floodplain standards, such as marinas, RV parks and restaurants elevated on stilts. But flash flooding doesn't happen on major rivers-it happens on smaller rivers and inland creeks.

"We don't allow new buildings to be in any of our floodways, which is the most dangerous area of a floodplain," Hurlbert says.

Some isolated homes are near creeks, such as along the tributaries of Dardenne Creek through central St. Charles County. But the soil types and consistency here help place the county in a better position against a major flash flood similar to the Texas tragedy

"Our soil can soak up the rain better," Hurlbert says. "But the Guadalupe watershed in Texas is mostly clay. So, the water rose 12-20 feet in an hour. That happens because there's no permeability. The water has nowhere to go."

But all St. Charles County staff involved in disaster preparation agree the public must be fully prepared when warnings are issued, by heeding sirens, wireless emergency alerts, and having a NOAA radio in your home and at work.