The U.S. Army Corps of Engineers, which manages the six large dams athwart the main-stem of the Missouri River in Montana and the Dakotas, recently announced that the entire Missouri Valley from Montana through the state of Missouri faces the threat of damaging and costly flooding in the next several weeks. According to the Corps, this flood threat is unprecedented in the history of the Missouri. The Corps claims this flood is “unprecedented” because of the amount of water now, or soon to be, descending the river. I believe it is unprecedented for another reason.
It is important to understand that the Missouri River has experienced massive floods in the past. As a matter of fact, prior to the construction of the Army’s big 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. Much of the flooding from the Missouri’s first flood of the year resulted from ice jams, which blocked up the river and forced the Missouri’s high flows into the surrounding valley lowlands. The most powerful and damaging April rises since European-American occupancy of the Missouri Valley 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. Nineteenth-century steamboat travelers along the Missouri noted that during the month of May, sandbars (which frequently obstructed the passage of the steamers) made their dreaded reappearance in mid-channel. However, the Missouri bounced back up again in June, when the river’s second annual flood took place. Valley residents knew this second 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. It was not unheard of for the June Rise to continue well into July. Although infrequent, the Missouri could even remain in flood into August. However, in a normal year, the Missouri began to shrink back within its banks by August, as the scorching plains sun, and the accompanying winds, dried the land. But with the June Rise, the Missouri earned its nickname “The Mighty Mo.” During this flood, water might stretch from valley wall to valley wall from the Dakotas all the way south into the state of Missouri. The Missouri could also increase its volume to ten times its normal flow rate. For example, at Sioux City, the average, daily, pre-dam discharge rate stood at approximately 30,000 cubic feet per second. Yet, in June, the river could easily reach a daily discharge rate of 300,000 cubic feet per second. Wildlife, and the valley’s human inhabitants, fled from this swirling, silt-heavy, and debris-filled river. One of the largest June rises struck the lower Missouri Valley and the two Kansas Cities in June 1903.
Thus, the historical record indicates that the Missouri flooded regularly prior to the construction of the Army’s earthen dams. Even the present high flows in the Missouri River are consistent with the river’s past hydrological character. This year’s projected Missouri River flood is another very big June Rise. The floodwaters now pouring across Montana and the Dakotas and into the Missouri are the result of both a heavy Rocky Mountain snowpack and monsoonal thunderstorms. The snowpack in the mountains of Wyoming and Montana stands at well over one-hundred-percent of the yearly average. Additionally, some regions of the plains have received a year’s worth of precipitation in just the month of May. Deep mountain snows and heavy rains on the plains have long contributed to major June rises. 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 dams to prevent floods. One of the key advocates for the construction and maintenance of the dams at Gavin’s Point, Fort Randall, Big Bend, Oahe, Garrison, and Fort Peck was a politically-savvy general named Lewis A. Pick. Pick headed the Missouri River Division of the Corps of Engineers in the mid-1940s. He was later promoted to the position of Chief of Engineers (the highest position attainable in the Corps of Engineers) because he did such a brilliant job of ensuring the Army’s political dominance over the apportionment of the Missouri River’s waters.
In the 1940s and 1950s, Pick and his subordinate officers at the Missouri River Division acquired congressional funding for their series of dams by promising both congressional representatives and Missouri Valley residents that their colossal dams would end the Missouri’s annual floods. After the completion of the main-stem dams (the Army finished the last one at Big Bend in 1966), the Corps asserted that it had “tamed” the Mighty Mo. Believing the flood threat to be gone south of Yankton, and receiving encouragement from the Corps of Engineers to develop the valley lowlands, business owners built factories in the river’s former floodplain. For the same reason, homeowners constructed very expensive McMansions directly on the banks of the river at places such as Bismarck, North Dakota, Pierre, South Dakota, and Dakota Dunes, South Dakota. State highway departments followed suit. Hard-surfaced roads appeared at the river’s edge. Farmers also got into the game. They converted former Missouri Valley floodplain land to corn and soybeans. From the 1970s onward, it became a common sight to see lower valley farmers plowing and planting within mere feet of the Missouri’s fast-moving waters.
Today, because of the Army’s earlier statements professing dominance over the Missouri, and because of American society’s subsequent encroachment on the river’s floodplain, the valley and its residents confront an emerging disaster of historic proportions. But rather than blame the coming flood, and the expensive damages that are likely to result from it, on a wrathful Mother Nature or the onset of global warming (although global warming may have been a contributing factor in the heavy rain events in Montana and the northern plains in recent weeks), we all would be better served by examining how the Army’s history along the river contributed to the present flood. What is apparent now is that the Army’s promises of flood prevention were off the mark. The dams have not stopped the Missouri’s flooding. Do you remember the Missouri River flood of 1993? That flood hammered portions of the river south of Sioux City, Iowa, even with the reservoirs in Montana and the Dakotas holding back a portion of the floodwaters. The coming flood looks as though it will far exceed the 1993 flood in inundated area and economic costs. Additionally, the Army’s assertion of having “tamed” the river created a false sense of security among valley residents. Such overconfident Army proclamations convinced residents into believing they could build their homes, their factories, and their farms in the former floodplain with immunity from floods.
The Great Missouri River Flood of 2011 already provides lessons. More lessons will be forthcoming in the months ahead. But for now, what is obvious is that human engineering works – no matter how large and imposing – will never prevent flooding. Secondly, American society needs to back away from the Missouri. The costs of this year’s flood will be high because people built too close to the river. And finally, and most importantly, the American public should forever doubt the U.S. Army Corps of Engineers’ assertions of environmental mastery.