Washington — The ecosystem of the Missouri River will suffer irreversible damage without a return to a more natural ebb and flow, an undertaking that could cause flooding and entail moving entire communities, the National Research Council reported Wednesday.
Releasing the results of a two-year study, the council said the nation's longest river has lost so much natural habitat and so many fish, birds and other animals over the past century that it "faces the prospect of irreversible extinction of species."
"Degradation of the Missouri River ecosystem will continue," the council said, without returning in some measure to the flow of water and sediment that once came naturally. The panel of science called for "flow pulses that emulate the natural hydrograph, and cut-and-fill alluviation associated with river meandering."
Allowing the river to meander would require a much wider public corridor in portions of the channel, the council said, and "relocation may represent a viable option in some instances." The council cautioned that displacement "must be conducted very carefully, as it may entail significant monetary and psychological costs."
In addition, Congress should mandate that improving ecological conditions holds the same importance as barge traffic, flood control and hydropower, the council said.
The report comes as the U.S. Army Corps of Engineers considers a more seasonal ebb and flow along the Missouri, which flows 2,341 miles through seven states, from Three Forks, Mont., to St. Louis. The council, a division of the National Academy of Sciences, performed its review at the request of the corps and the federal Environmental Protection Agency.
Dams and channels have straightened the river, eliminating meandering, miles-wide loops, shortening the Missouri by roughly 200 miles and washing away all but 2 percent of the sediment that once earned the nickname "Big Muddy." Today, the federal Endangered Species List includes the river's pallid sturgeon and two species of shorebird, the least tern and piping plover; 50 other native fish species are listed as declining, too.
The corps has proposed a half-dozen alternatives to its decades-old dam and reservoir operations, including doing nothing. But the most controversial is a seasonal plan to mimic how mountain snowmelt makes the river surge, releasing more water every third spring and lowering the water levels each summer. The U.S. Fish and Wildlife Service insists the changes are the only way to comply with the federal Endangered Species Act.
But despite its call for more natural flows, the report does not recommend specific changes or endorse any alternatives currently under consideration. In fact, the council calls for a moratorium on further changes until the corps switches to a more flexible, collaborative approach that gets input from everyone affected as well as a panel of independent scientists.
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