More flood storage has limited benefit to Missouri River, corps says

More flood storage space in the Missouri River’s reservoirs would have reduced, but not prevented, last year’s devastating floods, the U.S. Army Corps of Engineers says.

In a report released Friday, the corps said there still would have been widespread flooding damage last year because of the massive volume of water that moved through the river.

It also noted that any increase in the amount of flood storage space in the reservoirs would reduce the economic benefits the river offers through barge traffic, recreation and hydropower. In fact, all the other uses of the river besides flood control require more water to be held in reservoirs, not less.

But increasing flood storage space in reservoirs is just one option to reduce flood risk, and corps officials said it may not be enough.

“It’s going to require a significant effort and investment over time if we’re going to reduce risk,” said Brig. Gen. John McMahon, commander of the corps’ Northwestern Division.

Reducing the flood risk along the Missouri River over the long run might require changing the way communities and states think about development in the flood plain and widening the levee system to allow for more room in the channel, McMahon said.

Some of the same measures were recommended after past floods, McMahon said, but weren’t done because they are costly and require significant political will.

“The 2011 event reminds us of what we learned just a couple decades ago after the 1993 flood,” McMahon said.

Last year, flooding caused at least $630 million of damage to flood control structures along the 2,341-mile-long river. Hundreds of thousands of acres of farmland also were damaged along the river, which flows from Montana through North Dakota, South Dakota, Nebraska, Kansas, Iowa and Missouri.

The latest report is part of the analysis being done to determine whether the corps needs to increase the 16.3 million acre-feet of space that is normally cleared out each spring for flood control purposes.

The report is designed to spur debate, not make a recommendation. Several other reports are expected to be completed before fall, when the corps will develop next year’s plan for managing the Missouri River.

The report drew quick criticism from some quarters. Rep. Steve King of Iowa said it was flawed because it didn’t consider how economic development and life along the river could be helped by better flood control.

“We must provide protection to those who live and work in the Missouri River basin so that life there can continue and redevelopment can take place,” King said. “We cannot do that, however, with incomplete reporting from the corps.”

Last year, heavy May rains combined with above-average snowpack caused the flooding.