Five months ago, Army engineers in a downtown Omaha office building fed computers with the latest snowfall data and predicted another potentially wet year along the Missouri River.
Simultaneously, the public works director in a little South Dakota city 450 miles upstream — and just below the towering face of Oahe Dam — crunched the numbers himself.
He was stunned.
By Brad Lawrence's seat-of-the-pants calculations in Fort Pierre, the Mighty Mo appeared poised to unleash “a flood of biblical proportions.”
Lawrence fired off an email to the American Water Works Association in Washington, D.C. He warned that river communities along the Missouri should prepare for flooding and stock up on sandbags.
“This may be one for the record book,” he wrote on Feb. 3.
Lawrence's hunch was prophetic, but not widely known.
As record Missouri River flows from dams in Montana to Nebraska breach levees, force evacuations and inspire around-the-clock flood-fighting along the nation's longest river, frustrated victims and others are asking if the Army Corps of Engineers' by-the-book management of its dams during a year of heavy snowfall and record rainfall contributed to the unprecedented flooding.
Water and climate experts, emergency managers and elected officials up and down the river were mixed in their reviews of Army engineers' decisions and actions — guided by their 432-page, congressionally approved and court-tested Master Manual, the bible of Missouri River management.
The manual is the problem, say Missouri U.S. Sens. Roy Blunt, Republican, and Claire McCaskill, a Democrat, who promise congressional review.
Fix the flood first, then investigate, says Rep. Steve King, a Republican whose western Iowa district includes some of the hardest hit communities and farms.
“I can't lay the flood at the feet of the corps,” he said.
There will be an opportunity for fact-finding, but an unfortunate set of circumstances coincided to create the flood, said Al Berndt, assistant director of the Nebraska Emergency Management Agency.
“I can't second-guess what the corps did,” he said.
No one could have predicted that the semi-arid high plains of Montana would be drenched with off-the-charts rains that poured millions of acre-feet of water into the upper Missouri in late May, said Gina Loss, a National Weather Service hydrologist in Great Falls, Mont.
All of eastern Montana — a region roughly the size of Nebraska — received more than 200 percent of its normal May rain. The eastern third of the state measured rainfall at more than 300 percent of normal. A gauge in the Judith River basin, a Missouri tributary, collected nearly 11 inches of rain where 3.6 inches is normal. Some places measured rains of more than 15 inches.
“Half of Montana got nearly a year's worth of rain in a few days,” Loss said. “It was incredibly rare. I can't emphasize that enough.”
A nearly 12-month supply of water — based on historic runoff averages — poured into the basin above Sioux City, Iowa, during May and June combined.
Adnan Akyüz, North Dakota's state climatologist in Bismarck, said the snowiest winter ever and the second-wettest spring in western North Dakota — a region that usually receives meager precipitation — created perfect conditions for flooding.
It would be easy to predict runoff without dams because water that flows into a river flows out, he said.
“But when you inject humans and dams, they have more impact on flooding than the climate,'' he said. “The idea behind dams is to release or hold water based on what's expected. Sometimes forecasts are true. Sometimes they're not true.”
Loss said the cool spring in the Montana mountains has been a blessing because it prevented historic snowpack from melting on schedule and joining the big rainfall runoff in May.
“We would have had a much bigger flooding problem than we're dealing with,” she said.
Lawrence, the Fort Pierre official, didn't base his flood warning on the expectation of historic upstream rainfall in the Missouri. Rather, he anticipated flooding in the Mississippi and Ohio Rivers, plus the James and Big Sioux Rivers — both Missouri tributaries — in eastern South Dakota.
Widespread flooding in those places, he said, would compel the corps to hold back water in its system of six Missouri River reservoirs to alleviate downstream flooding, especially at the mouth of the Missouri — at the Mississippi.
The reservoirs would fill to capacity. Once full, the corps would be forced to release massive volumes of water, creating flooding. Lawrence said the corps failed to lower its reservoirs enough to meet normal runoff conditions.
Corps officials dispute his claims, saying they don't operate the Missouri to accommodate the Mississippi. They also said the full flood-control capacity of the Missouri dams was available by late January — and that it was unclear until early April this would be a year of higher-than-normal reservoir releases.
By early May, the corps accelerated its releases of floodwater and said 2011 had the potential to be the second-highest runoff season in 113 years of recordkeeping.
Lawrence said the water content of Plains snowpack around Garrison Dam in North Dakota caught his attention. He said he thinks the corps' calculations don't accurately factor how much water is held in snowpack on the Plains.
He noted, for example, that Oahe Reservoir — the second-largest corps impoundment nationally — gained 4 feet more in elevation during March than the corps forecast. The lake then rose nearly a foot more in April than projected, he said.
“That's not a minor miscalculation or misinterpretation,'' Lawrence said. “That's a very gross miscalculation. It's an astronomical miscalculation of the Plains snowpack runoff.”
Jody Farhat, who regulates the dams as chief of the corps water management office in Omaha, said Plains snowpack received added attention this year because it played a significant role in last year's flooding.
King said he understands that people want to blame someone for the flooding.
“There's more water than we've ever seen coming down the Missouri,” he said. “It's an ocean. It's eight to 11 miles wide in places. We will lose businesses, and we will lose people.''
King, whose earth-moving business has done levee work on Missouri tributaries, said the corps could not have prevented the flood by lowering the water level in its dams without changes to the manual or “unless they had someone who was clairvoyant and could convince people they knew the flood was coming.”
King said he has asked the corps to produce a hydrologic model showing how it would have managed the reservoirs to avoid flooding, based on what is now known.
“I see that as a baseline to changing the Master Manual,” King said.
Stuart Maas of Bellevue, who is an owner of a hunting lodge in the flooded bottomland near Hamburg, Iowa, said the corps should not hide behind its manual.
“That is a terrible excuse,'' he said, “to say that a piece of paper limits what you can do when your own judgment says it should be done.”
Maas said the river flooded his land for nearly three months last year.
“We had a dress rehearsal last year,” he said. “The river was talking to us.”
Maas said the corps should lower levels of the largest upstream reservoirs to create more space for spring runoff and flood control. He doubts it will happen, he said, because barge interests in Missouri would fear having too little water in the reservoirs to release for floating vessels in the summer.
A 2003 court decision says that flood control and navigation are the dominant functions of the reservoir system. The corps says flood control is its top priority.
Berndt said Nebraska emergency managers were aware of expected high flows in the Missouri this spring and have been fighting minor lowland flooding in Boyd and Knox Counties for more than a year.
“We knew we were going to have some flooding, but we didn't expect this magnitude,” he said. “The problem is the duration of flooding. It's unprecedented.”
Lawrence said he hopes that honest assessments are made after the flooding to be better prepared in the future.
“This isn't a ‘gotcha' thing,” he said. “I'm not an expert. Like Yogi Berra said, ‘You can observe a lot just by watching.'”
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