During the construction of the Missouri River navigation channel, the Army erected thousands of pile dikes and revetments to narrow, deepen, and straighten the wide, shallow, meandering stream. Once the engineering works went into the river, the Missouri deposited its heavy silt-load on the downstream side of the structures. Overtime, new, elevated lands appeared in the river’s floodplain. Side channels, marshlands, and scour holes – everything that constituted the floodplain – filled with alluvium. Accumulated sediments sharply reduced the floodplain’s ability to store floodwater. Valley farmers benefitted from the newly accreted land. They expanded their operations into the floodplain, planting row crops where native vegetation once grew. The floodplain’s loss meant the farmer’s monetary gain.
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On Thursday, November 3, 2011, members of the U.S. Army Corps of Engineers met with the public in Sioux City, Iowa, to discuss the flood of 2011 and the management of the Missouri River in the months ahead. The public finally had a chance to vent its anger at the object of its long-held scorn – and vent it did. When the clean-cut, straight-laced Brigadier General John McMahon took the podium and told the surly crowd that he continued to have full confidence in the skills and abilities of his Missouri River reservoir operations staff – the same staff that determined the reservoir release schedule this past spring with such disastrous results – the audience erupted in a cacophony of catcalls and boos. But the general, who appeared in front of the throngs in his battle dress uniform, stared back at the seething mass of humanity and repeated the statement a second time – to more boos and sighs. Continue Reading »
In 1946, the Burt County (Nebraska) Bridge Commission sought the approval of the federal government (which has authority over the Missouri River) to build a bridge over the river linking Decatur, Nebraska, with Onawa, Iowa. Government officials approved the request with one stipulation. The new bridge had to be built over the planned course of the yet-to-be-constructed navigation channel, rather than over the existing course of the river, which flowed 500 feet to the east. Continue Reading »
Tagged Army Corps of Engineers, Decatur, Decatur Bridge, Fort Randall Dam, Iowa, Missouri River, Missouri River Flood 2011, Missouri River Navigation Channel, Nebraska, Onawa, Tieville Bend
From 1929 to 1940, the Great Plains experienced a devastating drought. Scorching temperatures, an over-abundance of sunshine, and dry winds ravaged the land. From the Dakotas to Texas, soils turned to powder and blew away. In those hard, lean years, plains residents experienced hundreds of deadly dust storms. The Black Blizzards threw billowing clouds of dirt into the atmosphere, blotted out the sun, suffocated stock animals, and inflicted a phenomenon known as dust pneumonia on the rural population. Untold numbers died from the respiratory ailment. Continue Reading »
In the 1930s, FDR provided funds to the Missouri River Navigation Project because he believed that a barge navigation channel from the river’s mouth to Sioux City would eventually carry enough commercial traffic to justify the cost of construction. He also hoped that the establishment of competition between barge companies and railroad corporations would lower transportation costs for Missouri Valley farmers and manufacturers. Valley residents would then invest the resultant transportation savings back into the Midwestern economy. Farmers would use their increased disposable income for the improvement of their farmsteads or for the purchase of tractors and trucks. Factory owners would invest in machines or hire more workers. The multiplier effect of the navigation channel would help lift the Midwestern economy out of the depths of the Great Depression.
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Two days ago, the Iowa Department of Natural Resources reported that 950,000 trees along the Iowa side of the Missouri River are likely to die as a consequence of the Great Flood of 2011. How the Iowa DNR came up with that figure is anyone’s guess. I think the figure of 1 million trees would have been a more impressive number, or maybe 2 million. The reality is that no one knows how many trees are going to die in the months and years ahead. But it is apparent that astronomical numbers of trees will die. Continue Reading »
The Great Flood of 2011 altered the Missouri’s channel morphology in noticeable ways. In the unchannelized river at the foot of Ponca State Park (Ponca, Nebraska) the flood has rearranged the riverbed. Where fast, deep water once pushed heavily downstream, there is now a football-field-sized sandbar. Next to it, a dark, muddy shoal is beginning to emerge from the depths. Just upstream, the river is now careening through a once-calm side channel. Northwest of the bridge linking Newcastle, Nebraska, with Vermillion, South Dakota, numerous sandbars are visible in mid-channel. After a summer adrift on the waves, the topsoil of the Dakotas has finally found a resting place here. Continue Reading »
The Army’s navigation channel through the Sioux City metropolitan area appears to have survived the Great Flood of 2011 with only minimal damage. Even though powerful currents pushed rocks off riprapped wing dams and knocked askew the wooden poles atop pile dikes, the dikes and revetments continue to hold their positions in the river. The Mighty Missouri did not completely grind them down and carry them away. Rather, the training structures are at this moment directing the Missouri’s flow through what the Army calls the “design channel.” Continue Reading »
U.S. Geological Survey hydrologists recently reported that the Missouri’s present flood is carrying far less sediment than previous floods. The reason is simple; the high flows are coming out of the Dakota reservoirs rather than from the Lower Missouri’s dirtier, uncontrolled tributaries. The upstream reservoirs are trapping the river’s silt load and discharging clearer water through spillways and outlet tunnels. Continue Reading »
Sioux City, Iowa. The persistent high water of the Missouri is beginning to take a toll on the trees lining the stream’s banks. The saturated soil around the roots of the trees no longer provides a strong base of support. Thus, when high winds or strong river currents strike the vulnerable trees, they easily tumble over into the floodwater. Dozens of large and small trees are lying on their sides in the engorged Missouri just a mile downstream from its juncture with the Big Sioux River at Sioux City, Iowa. The number of downed trees is going to increase exponentially as the summer moves toward fall and the Army keeps the discharge rate out of Gavin’s Point Dam at 160,000 cubic feet per second. The loss of bankline timber will increase runoff into the Missouri for years to come. Healthy timber tracts halt or slow runoff by storing water in root systems, trunks, and leaves. Once the trees are dead and gone, rain will hit the valley floor and more quickly drain into the Missouri. River edge trees also act as a natural means of bank stabilization. Trees slow down erosive currents, deflect water from the bankline, and keep valley soils from rapidly washing away. The absence of trees along the river will lead to intensified bank erosion. Additionally, the loss of timber strips adjacent to the river means that agricultural chemicals, feedlot fecal matter, and urban storm water (which contains automobile lubricants) will readily find its way to the Missouri. The destruction of river side timber will have serious negative repercussions for the health of the Missouri River ecosystem.
