Kansas officials are in talks with the U.S Army Corps of Engineers about piloting a technique known as “water injection dredging” to keep one of the state’s drinking water reservoirs from filling up with sediment — which is partly the result of soil erosion from farm fields along stream banks.
Tuttle Creek Lake, which supplies drinking water to a third of the state’s population including Topeka and Manhattan, Kansas, is already more than 50 percent full of sediment. The issue has forced the state to address the problem, which is not uncommon in reservoirs around the country.
The water injection dredging technique has successfully removed sediment from ocean harbors, ports and navigation lanes but it has never been applied to a reservoir. “It is a barge that travels across the water, injects water under pressure to the bottom (and) resuspends the sediment so that it can more easily flow out,” Water Office Director Connie Owen told members of the state legislature’s water committee Monday when describing how water injection dredging works. It could be used as early as fall 2023 on Tuttle Creek Lake.
“That reservoir is the workhorse of northeast Kansas,” Owen said.
Kansas has 24 reservoirs that were built by the Army Corps between 1940-1960 to help control floods and provide for recreation, drinking water and irrigation. All reservoirs face the issue of sedimentation infiltration; as rivers flow into these water bodies, they deposit soil onto the bottom. But climate change has increased heavy rainfall in eastern Kansas, where Tuttle Creek and a number of other reservoirs are located, and that may be contributing to more soil erosion along stream banks and sediment in the lake.
Both Kansas State University extension and the Kansas Department of Agriculture have worked hard to get farmers upstream of Tuttle Creek Lake to adopt practices such as no-till farming and planting cover crops “to help stabilize stream banks so that we eliminate, or at least mitigate, parts of that sediment that’s flowing into the reservoir,” said Ted Harris, a water quality specialist at the University of Kansas. “The main thing is to encourage people to sign up for those programs.”
Laura Totten, Project Manager, Planning Section, U.S. Army Corps of Engineers, Kansas City District, said her agency is asking the federal government for $2.8 million this year to help fund the project. That’s in addition to $4 million in appropriations that the Corps has already received from the federal government and the Kansas legislature. That money will go toward purchasing the dredging equipment, running it for several weeks during each season of the year and gathering data on the environmental effects of the increased sediment downstream of the reservoir.
That price tag is far cheaper than the $20 million that the state spent to conventionally dredge the John Redmond Reservoir after a severe drought in 2011 threatened the sediment-heavy reservoir’s ability to cool the Wolf Creek nuclear power plant. That dredging helped restore just 3 percent of the reservoir’s capacity.
Totten and John Shelley, Hydraulic Engineer, River Engineering and Restoration Section, U.S. Army Corps of Engineers, Kansas City District, said that if the project is successful, it could be a blueprint not just for other reservoirs in Kansas but for those around the United States.
“There are reservoirs around the country that are suffering the same kinds of problems with sedimentation in lakes,” said Shelley. “So this is exciting that we get to test it here first.”