Kansas owns water storage in 14 federal reservoirs managed by the U.S. Army Corps of Engineers. But the storage capacity of those lakes is gradually diminishing, as topsoil from waterways and farms upstream washes into the reservoirs and settles to the bottom. State officials are now trying to extend the life of the eastern Kansas reservoir where the problem is most critical.
The federal lakes were built mainly for flood control, but they’re also a crucial source of water. However, the reliability of that water supply in times of extended drought is no longer a given.
In 2013, the state negotiated an agreement with the Corps of Engineers to raise the level of John Redmond Reservoir near Burlington by 2 feet.
Earl Lewis, assistant director of the Kansas Water Office, said even that wasn’t enough to assure a reliable supply of water downstream in a prolonged drought.
“It is absolutely the lake that’s in most urgent need of help,” Lewis said. “It’s more than 40 percent full of sediment. Some other reservoirs — like Tuttle Creek, like Toronto — are in that same neighborhood, but their demand isn’t quite to the point where they’re putting the same level of pressure that we see here at John Redmond, where our ability to supply is not meeting the demand that’s placed on these reservoirs.”
In times of drought, Lewis said, the Neosho River could go dry without water releases from the lake. It came close to happening in 2012.
“The reservoir here went from full in May to down below 40 and even 28 percent by November, and so we saw a tremendous drop in the water supply in one year,” he said. “It really reinforced the fact that we don’t have enough storage here to make it through a prolonged drought.”
John Redmond is a vital water source for 19 communities and six industrial users. It also serves as a backup supply of cooling water for the nearby Wolf Creek nuclear power plant.
In an effort to reclaim some of the lake’s storage capacity, state officials began a $20 million dredging project in May.
On an unseasonably cold, gray and windy day in mid-May, project engineer Brad Hahn wore a white hard hat as he stood next to a large, diesel-powered booster pump on the shore.
“We have a dredge in the water,” Hahn said, “and it’s like basically a big vacuum cleaner, and it sucks up the material, pumps it into a slurry line, and then we pump the material to a disposal area.”
Hahn, who works for the Chicago-based contractor Great Lakes Dredge and Dock Company, said the booster pump moves 1,000 cubic yards of churned-up mud and water per hour from the dredge through six miles of 21-inch pipe to the containment ponds below the dam. There, the mud will settle and the water will be returned to the Neosho River, downstream of the dam.
The area being dredged is only a small fraction of the lake bottom in and around the original river channel, a few hundred yards from the dam. Hahn said the silt that’s been deposited in that area over the 50-year life of the lake is anywhere from 5 to 20 feet deep.
“As the sediment settles to the bottom, it raises the floor. So unless you raise the water level with it to maintain that water depth and that capacity, then you run out of capacity,” he said.
This is the first large-scale dredging project to reclaim storage capacity that the Corps of Engineers has approved. The state had to satisfy a host of environmental concerns, and the Corps of Engineers had to make sure the dredging would not jeopardize the structural integrity of the dam.
The six-month, $20 million dredging project will add enough storage capacity to offset another three to five years of sedimentation. At a time when the state is struggling to keep its budget out of the red, that may not sound like a cost-effective expenditure. But Gov. Sam Brownback resisted that argument.
“You know, we’re gonna be able to handle our budget,” Brownback said. “This is a significant long-term issue. We’ve had problems near-term. Our oil economy is down, our ag economy is down, we’re still not selling small jets. But oil has now bounced back up off of its floor. It’s not where it was. Ag has bounced back some off of its floor. You know, those things cycle on you. But long-term you need water, and that’s a good investment, I think, in almost any scenario.”
Brownback described the dredging as a legacy for future generations.
“For years, our predecessors invested in these reservoirs for us, and we’ve gotten to use them,” he said. “And now this is our turn, and you’re not going to build a lot of new reservoirs across Kansas, or across America. That just not going to happen, so you’ve got to put money back in them.”
Lewis, with the Kansas Water Office, conceded that dredging isn’t the most cost-effective way to approach the problem. The best solution is to prevent sediment from getting into the lakes.
That’s why the Water Office is helping farmers minimize soil erosion and covering fragile stream banks with rock or vegetation to keep them from washing away.
But under the best of circumstances, that will only reduce the sedimentation by about half. And with the lake already close to half-full of silt, Lewis said dredging is the only way to regain water storage capacity that’s already been lost.