This is the third in a three-part series examining sedimentation issues along the Missouri River, including the impact on the reservoirs, the changing river environment and how to best manage the system.
Whether it’s contributing to flooding, filling up reservoirs or disrupting ecological systems, sediment on the Missouri River now contributes to some stubborn problems.
But a mutually agreed on, cost-effective method to move sediment as the river once did remains elusive.
For the U.S. Army Corps of Engineers, there are no practical solutions to sedimentation issues yet.
“The challenge is it’s cost prohibitive to dredge it, or the flows needed to move it downstream would be very great,” said Jody Farhat, chief of the Missouri River Basin Water Management for the Corps.
John Remus, chief of the Hydrological Engineering Branch for the Corps’ Omaha District, said the Corps has no immediate plans to begin dredging or piping sediment around the dams.
The reservoir system was not built for managing sediment and it would take a good deal of investigation and input from those living along the basin before putting anything into effect, he said.
“That would entail quite a change to the way we manage the system,” Remus said.
Starting to manage sediment now without further study of how it affects the complex Missouri River system could lead to sacrificing other crucial uses such as hydroelectricity and flood control, he said.
Others, however, say more immediate action is needed to deal with the issue.
“It’s a question of we study it to death, but never come up with a solution,” said Howard Paul, the former executive director of the Missouri Sedimentation Action Coalition.
Paul said the Corps needs to recognize sedimentation as a serious problem and make it a higher priority, maybe over some of its other mandates such as navigation and conservation.
“The Corps said it can’t afford to dredge, but they are building sandbars for nesting for terns and plovers,” he said.
Paul also suggested practical measures to cut down on erosion such as rip-rapping, or armoring with rocks, the banks of the reservoirs.
Larry Weiss, president of the Missouri Sedimentation Action Coalition, said dredging is the most practical solution despite the costs. But he also recommended better land management practices to reduce sediment getting into the system.
The Bad River Water Quality Project, a system of erosion control measures enacted in the past 20 years along the Bad River watershed area, cut the sediment reaching the Missouri by 30 percent, Weiss said.
W. Carter Johnson, a professor of ecology at South Dakota State University, sees two solutions as the most effective. The first is re-regulating the dam system to mimic the natural flow of the river. If that is not feasible, the second is controlled flooding to move some of the sediment through the river system, he said.
However, because of bank stabilizations and the lack of sediment in the system, even these measures might not send sediment to the Gulf of Mexico as the river once did, he said.
“We have a deficit, and sediment would get caught up by other areas before getting downstream,” Johnson said.
Paul said flushing sediment through the system is not viable, because a high power flush from a dam will eventually hit slower moving water and the sediment will drop out there. Like Remus, he said it would require reconfiguring how the reservoir system works.
John Cooper, a member of the state Game, Fish and Parks Commission, said even if a practical system to move sediment is found, it’s doubtful the American public or a U.S. Congress with budget deficits is going to pay to pipe sediment down the river.
“(It’s) the big gorilla: Who can afford to pay to get sediment out of the re-regulated dams below Oahe or the capacity reservoirs above it?” he said.
Cooper said politics also will come into play. The Lower Brule and Crow Creek reservations might object to moving sediment, because they would see mud being passed their way. Also, states on the lower parts of the river, such as Iowa and Missouri, would fight a more natural flow to the river because it would increase flooding, he said.
“It’s all social opposition because people don’t understand it’s all recreating the natural flow of the river,” Cooper said.
The federal panel on which Johnson served in recent years to study the sedimentation issue on the Missouri came up with several recommendations in 2010, including the suggestion that the U.S. Army Corps of Engineers and the U.S. Geological Survey go on collecting data about the sediment issue and also develop a “sediment budget” for the entire river. It could be a first step toward addressing some of the sediment issues on the river.
Weiss said, for the moment, it’s important to just raise awareness because, unless someone hits a sandbar while boating on a reservoir, people don’t see or think about sedimentation.
The lack of a long-term solution to the issue doesn’t surprise him, he said.
“It’s not something that came about in a few years or will be solved in a few years,” Weiss said.