The Tale of Two Rivers (and one very large river basin): as the Mississippi River flooding lingers, communities along the Missouri River are witnessing unprecedented flooding

June 10, 2011 | Floods & Floodplains, Protecting Rivers, Restoring Rivers, Dams & Dam Removal, Global Warming, Most Endangered Rivers, Small Streams & Wetlands

Shana Udvardy
Director, Flood Management Policy

As communities begin to recover from flooding along the Mississippi River, communities along the Missouri River [PDF] from the Dakotas to Iowa to Nebraska to Missouri are bracing for unprecedented flooding.

The flooding is unprecedented due to record levels of snowfall (see NY Times image below) in the Rocky Mountains, snow that is late to melt (it’s now about  250 percent of normal for this time of year), on top of extraordinarily heavy rains in May (some parts of Montana received nearly a year's worth of rainfall in just two weeks).

So what do the Missouri River and Mississippi River flooding events have in common?  While flooding is natural, both of these flood events represent unnatural disasters due to past efforts to “control” the rivers with levees, floodwalls and dams and paving and plowing over natural areas that help to store and convey floodwaters.  However, each of the rivers differs in the way they have been “controlled”.

For the most part, the Mississippi River is constricted by levees and floodwalls (see image of levees below) and the Corps of Engineers (the Corps) relies on floodways and spillways to manage record flows.  On the other hand, the Missouri River is constricted by a series of six dams (see image of basin & dams below) and the Corps relies on different flow regimes to manage record flows.  While the Corps manages flooding differently on the two rivers – each river illustrates how we’ve changed the natural flow regimes of big, powerful rivers while allowing people to move into harm’s way, behind and below these structures that can and will fail.

As the Corps plans to release a record 55,000 cubic feet per second (cfs) flow (this is 20, 000 cfs more than the record flow back in 1975), we need to ask ourselves whether we are truly managing these flood events in a way that can best safeguard communities and protect the environment and whether the management scheme the same for both rivers?

To start, in a changing climate we need our federal agencies armed with the best available science so that they can adequately predict and simulate impacts because we will continue to see an increase in the frequency and intensity of storm and snowfall events.   In the case of the Missouri River, because the Corps hadn’t predicted high water last fall, their operating plan wasn’t flexible enough to handle the conditions we are seeing now.  While the Corps pledges to understand that “stationarity” (or the notion that the past accurately represents the future) is dead, there are still major improvements needed to see this in practice. 

We also must allow room for rivers – this means allowing the floodwaters to be conveyed and stored naturally by wetlands and floodplains.  While we are dealing with highly manipulated systems, we can and must find ways to manage rivers more naturally by creating more floodways and bypasses and by investing in the protection and restoration of our “natural defenses” – our rivers, wetlands, floodplains, upland and coastal areas. 

A hard fought battle over the Missouri River management spawned the Missouri River Recovery Program (MRRP).  This program will create habitat for the endangered pallid sturgeon, the piping plover, and the least tern, modify flows to replicate more natural events, and invest in science and public involvement programs.  While this is a step in the right direction, comprehensive changes are needed at the national level.  The Obama administration has an opportunity now to overhaul the “principles and guidelines” that govern dams, levees, and other federal water resources projects.  We need national leadership to ensure the implementation of approaches that invest in our natural defenses. The NY Times got it right in their recent editorial on May 27 “A New Flood, Some Old Truths”:

“What is clear is that we should learn from our mistakes, let nature help out where it can, and not build or farm in places where it makes no sense to do so. As the saying goes: Nobody ever beats the river.”

We couldn’t agree more.

References:
NASA Earth Observatory
U.S. Army Corps of Engineers Missouri River operating plan [PDF]
Missouri River recovery plan
Missouri River Mainstem Reservoir Bulletin (Updated 8 Jun; 0900 CDT)
U.S. Army Corps of Engineers Missouri River Basin Management Division 
U.S. Army Corps of Engineers Spring Flood 2011

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