Record precipitation, reservoir releases to cause Missouri River flooding

Wednesday, June 1, 2011 | 7:13 p.m. CDT; updated 11:14 a.m. CDT, Monday, June 6, 2011
The Missouri River overflows on its banks in Sioux City, Iowa, on right, on Tuesday. At left, the rising waters have partially submerged soccer and baseball fields in a park in South Sioux City, Neb.

COLUMBIA — Wayne Hilgedick gets anxious when the Missouri River hits 25 feet. That's 7 feet below the levee that protects his corn and soybean crops in the Hartsburg river bottom, but in the six decades that the 79-year-old Hilgedick has worked that land, he's seen the river gain 2, 3, even 4 feet in one night from rainfall.

The river could gain that much by the middle of this month — without a drop of rain.

The Missouri River was forecast to reach levels between 27 to 33 feet at Boonville in the next few weeks and remain well above its 21-foot flood stage for most of the summer, according to the Army Corps of Engineers and National Weather Service.

The forecast flood levels are the result of record releases of water from reservoirs on the upper Missouri River in Montana and the Dakotas. The upper Missouri River basin received a year’s worth of rain in the past few weeks, and snow pack runoff into the upper portion of the river is 140 percent of normal, according to the Weather Service.

Gavins Point Dam, a dam on the South Dakota-Nebraska border that's closest to Missouri, is set to reach peak releases of 150,000 cubic feet in coming weeks — more than double record releases in 1997.

The releases roughly 600 miles upstream would reach Missouri in a little more than five days, said Erik Blechinger, chief of the Missouri River Joint Information Center.  Flood levels were supposed to last at least through the summer, he said, and sustained levels on that magnitude could mean big changes for the river.

“The river we knew prior to this event is going to be an entirely different river,” he said. “There's a lot of sandbar deposition. I don't think you're going to see any sand this summer." Once the water recedes, he said, sandbars could be in different places.

Hydrologist Robert Jacobson of the U.S. Geological Survey office in Columbia said it's much easier to predict what will happen with the river nearer Gavins Point than it is further downstream near Columbia.

"It's going to be an experiment down here," he said. With releases twice as large as the previous record, he said, "there are substantive unknowns."

Those uncertainties include the location of sand deposits, formations of side channels and the shape of the river's channel. One thing that does seem certain, Jacobson said, is that submerged sandbars will remain that way during the summer.

Mike Cooper, owner of Cooper's Landing south of Columbia, said he has to cancel events when the river reaches 26 feet because the entry roads are under water. The 27-foot conservative end of the forecast means those roads would be a foot under water. If the river stays that high, Cooper said, it could essentially shut his business down for the summer.

Recreation on the Missouri River, in general, would likely be affected as well.

"There will be no sand, and people can't get to the boat ramps because they're under water," Cooper said. "There won't be much recreation on the river."

A river at perpetual flood stage can also wear away at levees, Blechinger said.

“Mother nature is the unknown. It could go past summer time,” he said. “That constant flow and constant pressure on a structure that's earthen clearly has an effect on it.”

Even if the river doesn't overflow the levee in Hartsburg, Hilgedick said 20 to 40 percent of his crops could still be damaged from water that seeps through the levee from underneath. That cuts into 20 percent of his profit, he said, and most likely would have similar implications for the handful of fellow farmers in the area.

"It's just a matter of getting more seep water," he said, adding that some water has already reached his crops. "It starts spouting more mole holes. Little varmints get in the levee, and it softens it."

If the river level exceeds 32 feet, Hilgedick said, it overflows the levee and will flood homes. At 33 feet, Cooper said, there's 3 feet of water in his store.

"There won't be anything going on then," Cooper said. "We may have to turn our electricity off, and the people living here would have to leave."

Director of Emergency Management for Columbia and Boone County Zim Schwartze said her office expected the situation but believes the county is well prepared.

"With the hard snowfall that we had up north and here, we knew this could be potentially an issue," she said. "The city and county will be meeting this week to form a plan of action because it appears there will be several locations in and around the county that will be impacted by the release."

Six different reservoirs upstream of Missouri are releasing at record levels, and the Army Corps of Engineers forecasts five of those will exceed 150,000 cubic feet per second. The previous highest release from Gavins Point was 70,000 cubic feet per second in 1997.

“Virtually all of the reservoir storage we intended to utilize to manage the snow melt runoff has been filled up,” Jody Farhat, chief of the Army Corps of Engineers’ Missouri River Basin Water Management Division in Omaha, Neb., said in a conference call Monday.

According to the Corps, the releases would increase the river's flow to at least 260,000 cubic feet per second at Boonville, possibly as high as 420,000 cubic feet per second. That translates to at least 6, possibly as high as 12, feet above flood stage if the river receives what the Corps and the National Weather Service deemed “normal precipitation,” or the usual influx from tributaries.

A cubic foot of water can be compared to the size of a basketball, Jacobson said. On Wednesday, the Missouri River was 21.8 feet at Boonville, half a foot above flood stage, and was flowing at 166,000 cubic feet per second. Imagine watching 166,000 basketballs fly by every second, as Jacobson explains it. The Corps' forecast doubles that by the middle of the month.

Kevin Low, hydrologist at the Missouri River Basin Forecast Center, said it’s possible the river would exceed the forecast range of 27 to 33 feet at Boonville.

“I’m hesitant to give an amount,” he said, “but if there was an extreme event, with several days above average rain, those levels would be exceeded.”

Hilgedick said he's spraying his crops in hopes the river won't overflow into his fields, but he's also removing grains from storage bins and relocating equipment further inland in case it does.

If there is no rain, he gives the river a 50-50 chance of staying below the levees. "If we have heavy rains, I don't think the chance is that good," he said.

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Chris Cady June 2, 2011 | 9:43 a.m.

If this surpasses '93 it will just be unbelievable. Everybody head down there and buy some food and drinks from Mike Cooper while he's still able to be open for business!

(Report Comment)
Nicholas Blond June 2, 2011 | 11:07 a.m.

2010 and 2005 were tied as the hottest years on record. 2010 was the wettest year on record. Get used to floods and mega-storms of increasing frequency and severity--our government spends more on the military than the next ten countries combined, and until Republicans start believing in "science" we won't spend the piddly 1% of GDP (or raise taxes) to mitigate the risks of global climate change.

The slow, gradual damage caused by projected climate change will only continue to cost more and more, but America will still be spending her billions on tanks and next-gen F-22s with no reason whatsoever.

(Report Comment)
Mark Foecking June 2, 2011 | 1:08 p.m.

Nicholas Brown wrote:

"until Republicans start believing in "science" we won't spend the piddly 1% of GDP (or raise taxes) to mitigate the risks of global climate change."

I wish people wouldn't make it sound like "mitigating" climate change is a relatively simple thing.

First of all, stabilizing CO2 levels will require an immediate (within a few years) 90-95% cut in carbon emissions of the developed world, and over 50% cuts in emissions for China and India. There are no replacements for fossil fuels on anywhere near the scale we use them, so this would mean conservation, with truly devastating economic results.

It will take several hundreds of trillions of dollars to replace worldwide fossil fuel use with low carbon alternatives, and would take most of this century even under the most favorable national and international conditions.

We're going to be stuck with a lot of adaptation no matter what we do, and I feel preparing for more extreme weather, and learning to live with it, may be a more effective use of funds than trying to stop it.


(Report Comment)
Ellis Smith June 2, 2011 | 1:53 p.m.

To those with a simplistic view, everything is simple. It would nice if that were really true, but it is not.

(Report Comment)
hank ottinger June 2, 2011 | 3:53 p.m.

Mitigating the causes of climate change are indeed daunting, dare I say, Sisyphean. But in some quarters, Chicago for instance, steps are being taken to anticipate (and mitigate) the effects that many predict will occur as a result of climate changes, e.g., heavier precipitation, major wind events, etc. A forward-thinking community (or state or nation) would be smart to do likewise. Money spent on adaptations to these events would be far less than the costs resulting from devastating storms. Of course, thinking much beyond next Tuesday is something most people can't--or won't--do.

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