Emergency Work to Activate Flood Gates Highly Unlikely

West Des Moines Public Works Director Bret Hodne was so confident the city won’t have to lower flood gates at First Street and Grand Avenue this weekend that he went ahead with plans to see his son off to training for the Navy SEALs.

“I’m not saying it won’t happen,” Hodne said, “but the chances of it being lowered are very minimal.”

Lowering the floodgates would be more complicated than the only other time they have been activated – in August 2010, after a torrential rain event – since being installed as part of a levee protection system.

The flood wall and flood gates were built to protect Valley Junction and other parts of West Des Moines were devastated by the Floods of 1993. Ironically enough, work on the US. Army Corps of Engineers levee system was scheduled to start just days after July 10 floods proved the value of such a system.

The flood-gate system is in a state of disassembly with work to replace the Grand Avenue bridge over Walnut Creek on the Des Moines side of the intersection with First Street/63rd Street.

But should an emergency arise, a contractor is on standby and can quickly put an earthen structure in place that will allow for the same seal as if the gates were lowered to pavement, Hodne said.

If that happens, Windsor Heights city officials want to know. In Polk County Emergency Management discussions this week, Windsor Heights officials asked to be informed if West Des Moines does lower the floodgates.

“When West Des Moines lowers the floodgates, it backs the water up in Walnut Creek and it will flow into the Colby Park area more quickly,” Windsor Heights Police Chief Dennis McDaniel said. “It has the effect of somebody building a dam, more or less, and the immediate rise in water happens more quickly.”

McDaniel said that advance notice gives the city time to prepare and notify residents ner the park.

“They don’t lower it until it becomes necessary,” McDaniel said. “By the time they make that decision, we’re all already engaged.”

The channel is narrow, draining about 52,643 acres of land in Dallas and Polk Counties that make up the Walnut Creek Watershed, and it can be “flashy,” Hodne said.

“It comes up and goes down real fast,” Hodne said. “All that pavement through Windsor Heights and Clive make it come up very fast.”

Hodne said the flood gate on Grand Avenue, the one that is currently dismantled because of the bridge construction, has never been lowered. When the First Street gate was lowered about three years ago, it proved to be an unnecessary precaution.

“That was a pretty significant event in 2010, one that dictated closing the flood gate on First Street according to the standards by the Corps (Army Corps of Engineers), but the water didn’t even get to the gate,” Hodne said.

Both Hodne and McDaniel said forecasted rain that didn’t materialize over the past couple of days gave both cities some breathing room.

“Had we gotten some of the rainfall a couple of nights ago and the last couple of days that were in the forecast, I’d be very concerned,” McDaniel said.