The Corps of Engineers recently announced that the entire Missouri Valley from Montana through the state of Missouri faces the threat of flooding in the next several weeks. According to the corps, this flood threat is unprecedented in the history of the Missouri because of the amount of water now, or soon to be, descending the river. But it is unprecedented for another reason.
Prior to the construction of the corps's big Missouri River dams, the Missouri flooded twice each year. It flooded every April when the snowpack lying atop the prairies and plains melted and then poured into the river. Old timers referred to this first flood of the year as the April Rise or Spring Fresh (for freshet). The Spring Fresh lasted from a few days to a few weeks. The most powerful and damaging April rises occurred in 1881, 1943, and 1952.
Following the passage of the Spring Rise, the Missouri often dropped to below flood stage in late April and May. However, the Missouri bounced back up again in June, when the river's second annual flood took place. Valley residents knew this flood as the June Rise or Summer Rise. The June Rise resulted from the melting of the Rocky Mountain snowpack in conjunction with the advent of heavy thunderstorms across both the upper and lower Missouri basin. The June Rise carried more water, covered a larger area, and lasted for a longer period of time than the April Fresh. With the June Rise, the Missouri earned its nickname "The Mighty Mo." During the largest June rises, water stretched from valley wall to valley wall from the Dakotas all the way south into the state of Missouri. The Missouri also increased its volume to 10 or 15 times its normal flow rate. One of the highest June rises on record struck the two Kansas Cities in June, 1903.
The present high flows in the Missouri are consistent with the river's past hydrological character. This year's projected Missouri River flood is another large June Rise. But the soon-to-arrive Great Missouri River Flood of 2011 is unique. Why? Because it is going to happen all along the Missouri Valley in spite of the presence of the Army's six main-stem dams.
The Army built the Dakota dams to prevent floods. One of the key advocates for the construction of those dams was a politically-savvy general named Lewis A. Pick. Pick headed the corps' Missouri River Division in the mid-1940s. The Army later promoted him to Chief of Engineers because he did such a brilliant job of ensuring the Army's dominance over the apportionment of the Missouri's waters. In the 1940s and 1950s, Pick acquired congressional funding for the Dakota dams by promising an end to the Missouri's two annual floods.
After the completion of the main-stem dams, the corps publicly claimed that it had "tamed" the Mighty Mo. It also encouraged development of the river's former floodplain in order to solidify its political alliances with society's industrial, agricultural, financial, and real estate elites. Consequently, factories arose in the lowlands, McMansions appeared directly on the banks of the river, concrete roadways cut paths through old channel areas, and corn and soybeans flourished within feet of the river's fast-moving waters.
Today, Missouri Valley residents confront a disaster of historic proportions. But rather than blame the coming flood on global warming (although it may be a factor), we would be better served by examining the Army's role along the river. More specifically, how has the Army's navigation channel from Sioux City to the mouth, and the reservoir release sequence at the upstream dams, contributed to this, and other, damaging floods? It is a proven fact that the confined and straightened navigation channel reduced the lower river's carrying capacity and increased its channel velocity -- both factors increase the probability of floods and their destructive effects. Additionally, a greater drawdown of the reservoirs in the fall and winter will open up more floodwater storage space in the spring and summer. A reassessment, and alteration, of the Army's role along the Missouri might prevent a similar disaster in the future.
(Robert Kelley Schneiders has written two books on the history of the Missouri River, including "Unruly River: Two Centuries of Change Along the Missouri" (University Press of Kansas, 1999), and "Big Sky Rivers: The Yellowstone and Upper Missouri" (University Press of Kansas, 2003). He is the co-founder and director of Eco InTheKnow, LLC, Environmental Consultancy, Boulder, Colo., www.ecointheknow.com. )