Sediment Already Costing Region Millions Of Dollars, Official Says

An aerial view illustrates the growing sedimentation problem in the Missouri River, particularly Lewis and Clark Lake.

SPRINGFIELD — When it comes to Missouri River sediment, Rollin Hotchkiss says the Yankton region is already paying a high price.

Sediment has cost millions of dollars far beyond the river itself, the Brigham Young University engineering professor and researcher says.

Hotchkiss spoke Tuesday during the annual meeting of the Missouri Sedimentation Action Coalition (MSAC), conducted as a webinar because of the pandemic.

The impact goes beyond sediment filling Lewis and Clark Lake and the Gavins Point Dam operations near Yankton, he noted.

“If sediment management had already occurred at Gavins Point, the relocation of (Nebraska) Highway 12 wouldn’t have been necessary,” he said, referring to the major travel artery affected by Missouri River flooding. “That would be many millions of dollars and should be factored into any sediment management plan.”

In addition, Hotchkiss pointed to sediment’s impact on wildlife and the environment. In particular, he noted the need for creating sandbars downstream of Gavins Point for endangered or threatened species such as the least tern and piping plovers.

The sediment trapped upstream would provide major benefits, Hotchkiss said. “If it passed downstream, that would have a tremendous impact for the creation of those critical habitats,” he said.

Taking no action is a costly decision in itself, said hydraulic engineer Paul Boyd with the U.S Army Corps of Engineers.

“We have the ‘no action’ alternative going on right now,” he said during the webinar. “The river above Gavins Point Dam is filling with sediment, and the area below the dam is degrading due to lack of sedimentation.”

But a much larger view needs to be taken, Boyd said.

He works extensively with MSAC, noting any solutions need to show benefits outweighing the cost of taking action. That level can be reached by realizing no action on the Missouri River has consequences far beyond the Yankton region, he said.

The Corps is taking into account a number of areas in developing a sediment management plan, Boyd said. The Corps is completing the first of three phases in its scoping plans.

“For our study, we’re looking at the upstream and downstream beyond just the footprint of Lewis and Clark Lake,” he said. “We’re considering the lower Niobrara River and the Missouri River above the lake and also downstream of it. That makes it challenging in quite a few ways.”

In addition, any solutions must also look far into the future, Boyd said.

“Right now, we look at 50 years, but we need to be looking at least 100 years,” he said, noting consideration should be given to costs and needs 150, 200 and even 500 years into the future.

Planning models need to factor in all of the costs of maintaining dams and reservoirs for the Missouri River, Boyd said. In addition, long-term planning needs to take into account major needs for replacement, he added.

“You’re looking at de-authorizing and decommissioning projects and the construction of new ones,” he said.

In figuring the costs and benefits, a Missouri River plan needs to include the millions of dollars in activity generated annually by the dams and reservoirs, Boyd added.

“What are we willing to pay now for future generations so we don’t have to pay more later?” he asked. “What is the value of my grandchildren getting to go fishing on the lake, or of it still producing hydropower?”

The Corps is working with the Planning Assistance for States (PAS) program, which can provide a resource, Boyd said. In addition, the Corps is seeking to host a “solutions workshop” by this fall which would focus on the reservoirs and bring together national and international experts, he said.

“We’re looking for ideas we haven’t identified yet,” he said. “We want to take a deeper dive and develop some plans and figure how we would implement it and how much these actions would cost.”

MSAC members and other stakeholders would also play a major role in finding solutions with a favorable cost-benefit ratio, Boyd said. By acting now, answers can be found that benefit not only the Missouri River but also systems across the nation, Boyd said.

Hotchkiss commended Boyd’s work on sediment, including his presentation at MSAC meetings and elsewhere.

“I want the (MSAC) board to know how fortunate we are to have Paul Boyd working with us in the Omaha District,” Hotchkiss said. “I can tell you that Paul is very forward thinking in terms of economic analysis. He is willing to try out new ideas for sustainability. We’re fortunate to have him working with us. We’ve got a real ally.”

The planning for sediment management has moved forward and is ready for the next phase, Boyd said.

“I’m optimistic that we’re getting this thing started,” he said. “MSAC keeps us moving on this in a positive way, and we appreciate partners like that.

Much is at stake in finding and implementing a solutions sooner rather than later, Boyd added.

“Reservoirs are a limited resource,” he said. “Our goal is to make them last as long as we can and to provide benefits for as long as we can.”

Follow @RDockendorf on Twitter.

(1) comment


My grandpa helped build Gavins Point Dam, and also worked on Fort Randall. At the time those dams were constructed it was the plan to dredge both areas every ten years to help manage sediment and keep the channels clear. I've been around 50 years and there's only one time I can recall a dredge being used on the Missouri at Yankton and that was to clear out a boat ramp/beach area. I think the Corps should have kept with the original plan all those years ago and then we wouldn't have the mess we have today at Yankton/Niobrara/Wagner.

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