TOPEKA, Kan. (AP) — Two federal reservoirs in Kansas have been losing significant amounts of water storage capacity because of sedimentation, according to a study that the U.S. Geological Survey says also shows the reservoirs can't be expected to last indefinitely.
At least 95 percent of the sediment that flowed into Kanopolis Lake and Tuttle Creek reservoirs stayed in those reservoirs from October 2008 through September 2010, according to the study, which was conducted by the USGS and the Kansas Water Office.
The study ran from October 2008 to September 2010. Kyle Juracek, a research hydrologist who conducted the study, said water storage at Kanopolis, which is located outside Salina in central Kansas, has dropped 34 percent since the reservoir was created in 1948. Tuttle Creek reservoir, located near Manhattan in northeast Kansas, saw storage drop 43 percent since its creation in 1962. (An earlier version of this story implied the reservoirs had lost significant water storage during the study. That is incorrect.)
"This USGS study demonstrates that the useful lifetime for the valuable services of man-made reservoirs ... is measured in mere decades because they interrupt the natural sediment-transport process," Marcia McNutt, USGS director, said in a statement.
Kanopolis and Tuttle Creek reservoirs were built more than 50 years ago for water storage, flood control and recreation.
The study said the sediment came from the banks of upstream waterways, surface soil erosion and erosion along the banks of the reservoirs themselves. During the study period, about 600 million pounds of sediment flowed into Kanopolis, which was built in 1948. But about 31 million pounds flowed out. About 13 billion pounds of sediment flowed into Tuttle Creek reservoir during the two years, with about 327 million pounds flowing out. Tuttle Creek reservoir was built in 1963.
The study was expected to help the Kansas Water Office, which helps coordinate water planning in Kansas with the Kansas Water Authority, evaluate how best to manage sediment problems for the reservoirs.
Tracy Streeter, director of the Kansas Water Office, said in an email Tuesday that both reservoirs are important to Kansas and that the state has been looking at long-term water supply and demand issues and how best to slow sedimentation. Kansas also expects to use these reservoirs for water storage and supply "for several decades," he said.
"Good sites to build reservoirs are not plentiful in Kansas and the location of current reservoirs are really the best available," Streeter said. "In order to provide water supply for our citizens for the long term, we must treat these reservoirs as critical infrastructure that needs to be maintained."