2011 Missouri River Flood

The 2011 flooding event on the Missouri River in the United States was triggered by record snowfall in Rocky Mountains of Montana and Wyoming along with near-record spring rainfall in central and eastern Montana. All six major dams along the Missouri River released record amounts of water to prevent overflow which led to flooding threatening several towns and cities along the river from Montana to Missouri; in particular Bismarck, North Dakota; Pierre, South Dakota; Dakota Dunes, South Dakota; South Sioux City, Nebraska, Sioux City, Iowa; Omaha, Nebraska; Council Bluffs, Iowa; Saint Joseph, Missouri; Kansas City, Missouri; Jefferson City, Missouri, and St. Louis, Missouri. Many smaller towns were also at risk, suffering the same fate as the larger cities if not worse. According to the National Weather Service, in the second half of the month of May 2011, almost a year's worth of rain fell over the upper Missouri River basin. Extremely heavy rainfall in conjunction with an estimated 212 percent of normal snowpack in the Rocky Mountains contributed to this flooding event.

Background

The flood, rather than being a short term event, was anticipated to last from June through August 2011 as a result of attempts by the Corps of Engineers to regulate the release of water through of open river from Garrison Dam in North Dakota to the confluence with the Mississippi River at St. Louis. The Garrison Dam began releasing a record of of water per second on June 1, 2011—more than twice the previous record release in 1997. The Corps was criticized for not releasing the water earlier. However the Corps defended its practice noting that it did not foresee a cooler than normal spring which delayed the mountain snowmelt and the record sustained torrential spring rains in Wyoming and Montana.

In attempting to control the flood water release in since all the reservoirs were 100 percent or more of capacity (with the exception of the Fort Randall Dam), the Corps of Engineers doubled the record release of water in the river's five North and South Dakota dams. Officials said that problems downstream could have been alleviated by river control work and new levee construction that came about in the wake of the Great Flood of 1993. However, they were unsure whether the levees could sustain being waterlogged in a long-term flood.

A study by Utah State University examined the buildup of water storage leading to the 2011 Missouri River flooding observed by GRACE satellites indicated that precipitation over the MRB undergoes a profound modulation during the transition points of the Pacific quasi-decadal oscillation and associated teleconnections. The results infer a prominent teleconnection forcing in driving the wet/dry spells in the MRB, and this connection implies persistence of dry conditions for the next 2 to 3 years, which is linked to the 2012–2013 Midwestern drought.

Release of water by dam

In May 2011, dams above Gavins Point began stepping up the release of water (in cubic feet/second), exceeding all previous nationwide records for release.

Missouri River bridge closings

The flood forced the closing of several Missouri River traffic bridges from just above Gavins Point to northern Missouri. The closings made it impossible to cross the river for more than between Sioux City and Omaha and another between Plattsmouth, Nebraska (just south of Omaha) at Mile Marker 591 and St. Joseph, Missouri, at Mile Marker 450. Authorities were also considering closing the Plattsmouth Bridge.

During the flood, every bridge between Omaha and Kansas City was either closed entirely, had exit ramps blocked or had other work at some point.

Long term closings

* Chief Standing Bear Memorial Bridge between Nebraska and South Dakota near Niobrara, Nebraska. The bridge actually remained open but flooding on the Nebraska side made it a dead end. However some people (particularly employees at the Mike Durfee State Prison) used motor boats, kayaks, chest waders and a homemade “swamp bike” to commute between the bridge and their cars outside the flood area.
* Burt County Missouri River Bridge (Mile 691) between Nebraska and Iowa near Decatur, Nebraska
* Mormon Bridge (Mile 622) between Nebraska and Iowa north of Omaha, Nebraska ( Interstate 680)
*Bob Kerrey Pedestrian Bridge (Mile 616) – the pedestrian bridge between downtown Omaha and Council Bluffs which had been a popular viewing spot of the flood but was closed temporarily on June 30 while river debris was cleared from its base. The Council Bluffs side was closed on July 2 due to flooding on that side. It reopened September 3.
*Nebraska City Bridge (Mile 561) between Nebraska and Iowa (near Nebraska City, Nebraska)
* Brownville Bridge (Mile 535) between Nebraska and Missouri at Brownville, Nebraska
*Rulo Bridge (Mile 497) between Nebraska and Missouri at Rulo, Nebraska
* Amelia Earhart Bridge (Mile 422) between Kansas and Missouri at Atchison, Kansas. The bridge was open between Atchison and the small unincorporated community of Winthrop, Missouri, immediately across the bridge; however, access to Kansas City or St. Joseph on the Missouri side via U.S. Highway 59 was closed. Residents of Winthrop were evacuated on June 27.

Short term closings/interruptions

* Blair Bridge (U.S. Route 30) (Mile 648) -- The bridge closed for June 27-July 1 while flood barriers were erected in Iowa. It was also closed again July 6–7 for further shoring up work.
*Bellevue Bridge (Mile 602) – The bridge was closed June 27-July 2 due to flooding and sandbagging of Iowa Highway 370. Flooding in Haworth Park at the base of the bridge in Bellevue, Nebraska, had water up to the top of its basketball hoops on July 2.
*Pony Express Bridge (Mile 448) – South bound exit in Elwood, Kansas, was closed temporarily on June 28 while storm water could be pumped off
* Centennial Bridge (Leavenworth, Kansas) (Mile 396)- Scheduled resurfacing work on the bridge had started in May prior to the flood and traffic had been reduced to one lane. Since it was one of the few bridges open for traffic between Omaha and Kansas City, work on the bridge was halted indefinitely on July 1

Flood stages and effects by state

Montana

On May 22, 2011, flooding of the Little Bighorn River and nearby tributaries inundated Crow Agency and shut down Interstate 90 between Hardin and the Wyoming state line. May 26 flooding on Musselshell River inundated portions of Roundup. Waters from the Shields River entering the Yellowstone River created flooding that closed a portion of Interstate 90 from Livingston to Springdale. Flooding on Pryor Creek, another tributary of the Yellowstone River prompted closing of Pompeys Pillar National Monument.

North Dakota

On May 10 President Barack Obama declared much of North Dakota a disaster area over flooding which began on February 14 and had been continuing.

Some of the most dramatic flooding in North Dakota was on Souris River which comes close to the Missouri but is not a tributary as it flows instead north into the Assiniboine River in Canada, which also experienced prior flooding. 10,000 people in Minot were evacuated on June 1. On June 20 after they returned, officials announced that a new crest from new heavy rains would result in the river being a foot higher than the first crest. On June 21, 12,000 people, a quarter of the town's population, were ordered to evacuate after Lake Darling Dam had to step up its release of water. Amtrak suspended service on the Empire Builder through Minnesota, North Dakota and eastern Montana.

South Dakota

On June 1, nearly 3,000 people in Pierre and Fort Pierre were evacuated.

On June 3, South Dakota governor Dennis Daugaard urged residents in the Country Club section of Dakota Dunes (which is below Gavins Point Dam) to evacuate. He noted that it might be two months before they could return.

On June 21, South Dakota reported its first flood fatalities when two women drowned in Lyman County, South Dakota, after they drove their car down a washed out road. The fatalities were unrelated to flooding and increased releases on the Missouri River, but rather related to flash flooding from heavy rain
according to the Lyman County Herald of Presho, S.D.

On the same day Pierre, South Dakota, officials estimated costs from the flood would be $13.2 million for that community.

On June 30, the spillway at Big Bend Dam was temporarily closed for inspections.

Iowa

On June 10, the WinnaVegas Casino, which is owned by the Winnebago Tribe of Nebraska, near Sloan, was inaccessible. Shortly after, a yellow amphibious vehicle known locally as "the Duck" was used to provide transportation from Sloan across the floodwaters to the casino. The Duck now makes annual appearances as a float in Winnebago High School's homecoming parade.

On June 4, near River Mile 575 (near Hamburg), the main levee suffered a partial collapse. One June 5, it suffered a second partial collapse. On June 7, it suffered a third partial collapse. Finally, on June 13, it suffered a total collapse and had a wide gap. After the first partial collapse, the Corps of Engineers initiated an emergency contract to raise the levee immediately surrounding the town in order to protect it from an estimated of flood water.

On June 22, a mandatory evacuation of all residents in Mills County between Interstate 29 and the Missouri River was declared.

On June 25, a levee breach north of Council Bluffs flooded an area of Harrison County which could impact U.S. Route 30 connecting Blair, Nebraska and Missouri Valley, Iowa. DeSoto National Wildlife Refuge was also impacted by the break in the levee.

On June 27, officials said water "could begin slopping" over the emergency levee at Hamburg on its west side. The Nishnabotna River on its east side was reported to be two feet above flood stage.

On July 1, the main levee near Percival (16 miles north of Hamburg) breached in the early morning hours adding to the flooded conditions from the Hamburg breach. The breach occurred despite a month-long battle by the local residents.

On July 1, the privately owned Vanmann #30 levee at Mile Marker 637 to 637.5 on the Iowa side, about 10 river miles south of the reactor, was blown up by the local levee authority. The levee destruction was done to alleviate flooding in a bend of the river where water was pooling on cropland and creating an enormous water pool directly opposite the reactor. Authorities initially reported a rise in the river after the levee was blown. Both the US Army Corps of Engineers and the Iowa Department of Natural Resources said they did not regulate the levee. Flooding on the Iowa side had been a source of considerable concern after a June 25 levee breach upstream of the reactor near Missouri Valley, Iowa, prompted evacuations of 18 homes, temporary closing of the Blair Bridge (while flood walls were built to protect the Iowa approach) and closing of DeSoto National Wildlife Refuge on the DeSoto Bend. They had raised the levee height in anticipation of the flood but after the upstream breach they had sought permission to lower it so that water could flow back into the river. When both Iowa and the Corps said they did not have authority over it the levee board blew it up at approximately 10 a.m. on July 1. Pottawattamie County, Iowa, officials initially said they were notified only minutes prior to the levee being blown up, but those overseeing the levee had notified Harrison County, Iowa, officials earlier.

On July 1, the Corps reported that runoff on the river for June was the largest of any month on the river below Sioux City since record keeping began in 1898. June runoff was , beating the April 1952 record of . The third highest record was which was set in May 2011. The combined runoff for May and June was . The normal for the entire year is .

On July 11, officials at Sioux Gateway Airport said they were experiencing higher ticket sales. They speculated that the difficulty of driving from Sioux City and Omaha had spurred the increase.

As flood waters started to recede by late August, flood damage to Interstate highways 29 and 680 north of Council Bluffs, Iowa, was reported as extensive. Discounting the interstate system flood damage to county roads in Pottawattamie County alone was expected to amount to $40 million in repair costs.

Nebraska

On June 2, Scouts Rest Ranch, Buffalo Bill's home near the Platte River in North Platte, closed because of flood fears. Exhibits were moved and berms were built around the buildings. On July 13, officials said the flooding was not as severe as had been expected.

On June 4, Omaha city officials began releasing of raw sewage per day into the river from its plant in South Omaha. The city generates about a day, but only a small percentage is dumped into the river. The city of Omaha installed giant water pumps just east of Qwest Center Omaha to evacuate storm and sewer water directly into the Missouri River. By June 22, the city estimated 3 million dollars had been spent directly towards this flooding event.

On June 9, Nebraska reported its first event-related fatality when a worker was killed while working on a levee at Fort Calhoun when his truck tipped over.

The flooding affected the Fort Calhoun Nuclear Generating Station near Fort Calhoun, Nebraska, where the grounds of the plant were inundated by the flood, however, the plant had been in safe shutdown mode for refueling since April 2011. On June 6, the Federal Aviation Administration placed flight restrictions over the plant within a radius in which planes cannot fly lower than over the plant. On June 7, a fire broke out in the plant's switch gear room, prompting the Nuclear Regulatory Commission to declare an "Alert", which is level 2 on the NRC's emergency classification. Officials for the plant's owner, the Omaha Public Power District (OPPD), were confident that enough redundancies were in place to ensure adequate safety. The complex's elevation is elevation above sea level and as of June 19 the river had risen to . Officials from OPPD stated the Calhoun plant could handle water up to . An high and long rubber berm surrounded the reactor building. On June 23 a helicopter being used by OPPD to survey transmission lines made an unplanned landing south of the plant. The helicopter was photographed lying on its side but there were no reports of injuries. On June 26 the long rubber berm at the plant collapsed after it was punctured by a small earth mover ("Bobcat"). It was reported more than of water rushed in around buildings and electrical transformers. Backup generators were then used to ensure the facility maintained electrical power for cooling. NRC officials were at the plant at the time and NRC statements said the plant remains safe. NRC Chairman Gregory Jaczko

HOME


Content is Copyleft
Website design, code, and AI is Copyrighted (c) 2014-2017 by Stephen Payne


Consider donating to Wikimedia



As an Amazon Associate I earn from qualifying purchases