Perry Perry Lake is filling up -- and not just with water.
Since the reservoir opened in 1969, sediment runoff has taken away 23 percent of its water storage capacity, according to a new study from the U.S. Geological Survey and the Kansas Department of Health and Environment.
"That's the inescapable consequence of damming up a body of water," said Kyle Juracek, hydrology researcher for USGS.
The study, conducted during the past two years, shows Perry Lake receives more sediment than any other lake in Kansas studied so far.
To put it in perspective, annual sediment yield from the 1,117-square-mile drainage basin to Perry Lake was about three times larger than the same yield from Tuttle Creek Lake's much larger, 9,628-square-mile drainage basin, the study showed.
A study has not yet been done at Clinton Lake.
Perry Lake is not in danger of disappearing just yet, but it is a situation that caught the attention of researchers, Juracek says.
The U.S. Army Corps of Engineers built the lake for a 100-year lifespan, Juracek said. It is, however, filling with sediment faster than the corps expected.
"It's still going to be a viable lake for several decades," Juracek said. "At the end, there will still be a lake; it's just going to depend on how much storage capacity there will be."
The lake's operations manager, Frank Funk, agreed. "We've still got lots of lake."
But sediment runoff already has taken a toll on the lake. In the late 1980s, it caused the closure of two parks, Paradise and Sunset Ridge, located at the end of the lake where the Delaware River enters and dumps the largest amount of sediment, Funk said.
Sediment "silted in" the boat ramps there, causing them to be shut down. That, in turn, dramatically reduced the number of visitors to the parks, Funk said.
The sediment is carried into the lake by the Delaware, mostly from farmland runoff in its northeast Kansas basin.
|Test results of the U.S. Geological Survey's Perry Lake study and information about nine other reservoir sediment studies can be found online at ks.water.usgs.gov/ Kansas/ressed.
A limited number of copies of Water-Resources Investigations Report 03-4025, "Sediment Deposition and Occurrence of Selected Nutrients, Other Chemical Constituents, and Diatoms in Bottom Sediment, Perry Lake, Northeast Kansas, 1969-2001," can be obtained at the USGS office, 4821 Quail Crest Place.
The report also can be viewed online at ks.water.usgs.gov/ Kansas/pubs/abstracts/ wrir.03-4025.html.
"It has more erodible slopes -- steeper slopes," Juracek said.
The situation was not serious enough to require immediate action to reduce the sediment deposits, and there were no plans to clear what had built up, Juracek said.
Tests also showed the lake-bed sediment indicated eutrophic, or nutrient-rich, conditions have existed throughout the lake's history. Those conditions could result in excessive algae growth, which can lead to taste and odor problems for water suppliers, as well as aesthetic problems for recreational users.
The state of Kansas has the lake's water under contract from the U.S. Army Corps of Engineers through the Kansas River Water Assurance District No. 1 in order to supply cities including Lawrence, Olathe and Bonner Springs. The lake also helps provide water to much of Johnson County and industries such as Procter & Gamble and Colgate-Palmolive in Kansas City, Kan.
Researchers determined that about 7.6 million pounds of nitrogen and 3.3 million pounds of phosphorus were deposited along with the sediment each year in the lake. Nitrogen and phosphorus are nutrients commonly found in fertilizers and manure.
Traces of other elements and substances, such as arsenic, chromium, copper and nickel are also present.
Yet the water quality was considered good and was not a danger to the public, said Tom Stiles, KDHE's chief of watershed planning.
"What we found was pretty typical of lakes," Stiles said of the presence of chemicals. "It is actually a good-quality lake."
The lake would be tested for chemicals every few years, Stiles said. If problems develop, steps would be taken to target land management practices in the basin.
"Reservoir sediment can produce a wealth of information about past and present conditions, and can allow us to assess future changes that may be due to human activity," Juracek said.