Army Corps of Engineers: Managing the flood of 2011

Flood 2011

SIOUX CITY, Iowa (KCAU) — The rising waters of the 2011 flood in Siouxland caused countless problems for businesses and homeowners. Cleanup lasted for weeks and in some cases, years. Despite what it might have looked like, the infrastructure designed to keep damage to a minimum worked exactly the way it was supposed to.

“So 2011, we had a bunch of snowpack in the plains, also in South Dakota, North Dakota, Montana, and then we had mountain snow pack and a lot of rain in eastern Montana,” said Tom Curran, the current project manager at the Gavin’s Point Dam. “So that put a lot of water in the system.”

“So all of the water that comes into the Missouri River above here, has to go through Gavin’s Point Dam, so we had quite a bit,” said Curran.

By quite a bit, Curran means more than five times the normal amount of water per second running through the spill gates. As the waters kept rising, and the release numbers rising with them, residents we talked to say they were amazed.

“I was kind of surprised that they were going to release more,” said a bystander at the Gavin’s Point Dam in 2011.

At the peak of the event, the Army Corps of Engineers was releasing 160,000 CFS.

“I think everyone has a question mark going through their mind, whether the levees are going to hold or not,” said another bystander at the Gavin’s Point Dam in the summer of 2011.

That question was answered positively, to the relief of many.

“So everything really performed exceptionally in 2011. We didn’t have any issues,” said Curran.

That being said, the massive amount of water took its toll.

“A lot of erosion that we had to come in and repair after that 2011 event. We had to come back in and reshape the banks and put rock back in for the next event.”

The infrastructure itself also took a beating from constant high water levels.

“Anytime you run the dams that hard, for that long there is wear and year, and we see that. We did look at all the dams after that, especially our spillway gates. Those had the majority of the flow going through them,” Curran said. “The seals get worn, we look at the paint, we look at the structural steel and everything came through that event very well.”

At the end of the day, the dam did exactly what it was designed to do.

“But as far as the operation and maintenance, we’ve been doing this now for 60 or 70 years at these projects and nothing much has changed. We continue to inspect. We continue to maintain and to operate the dams,” said Curran.

So 10 years later, how does our spring runoff compare?

“So we had pretty good fall moisture. Since then, the winter has been pretty dry. And then it’s continued to be dry the last couple of months,” said Curran. “Every month, the reservoir control unit in Omaha looks at the condition of the basins and make a forecast for the year. This year, the forecast is really low. It’s like 44% of average.”

This is good news for Siouxland, but another flood event is inevitable, whether it’s next season or decades from now. The Army Corps of Engineers say they and the dams will be ready.

“They do function well when those happen, and they will continue to function when those happen,” Curran said.

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