2011 Missouri River Flood

Corps of Engineers photo of June 16, 2011, showing the Fort Calhoun nuclear power plant surrounded by flood water
NOAA map of flooding areas on June 18, 2011. The Missouri River is reflected by gages in the middle and top. Purple reflects heavy flooding and orange moderate flooding.
U.S. Weather Service map showing number of precipitation inches above/below year to date at June 18, 2011. The map shows that year to date precipitation in the Missouri headwaters basin of Montana had precipitation of 20 inches or more above normal while the rest of the basin precipitation was near normal. Above normal precipitation along the Ohio River led to the 2011 Mississippi River flood earlier in the year. Significantly lower than normal rain in eastern Arizona led to the Wallow Fire.

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.[1] 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.[2]

  1. ^ Missouri River Near Williston, North Dakota - National Weather Service
  2. ^ Cite error: The named reference :0 was invoked but never defined (see the help page).