Reservoir Sedimentation in Kansas: Quantity and Quality

By Kyle Juracek

Abstract

An understanding of the quantity and quality of sediment deposited in a reservoir is necessary for effective reservoir and basin management. Sedimentation affects both the useful life and aesthetic quality of a reservoir. Sediment quality is an important environmental concern because sediment may act as a sink for water-quality constituents and as a source of constituents to the overlying water column and biota. The U.S. Geological Survey, in cooperation with Federal, State, and local agencies, has completed reservoir sediment studies in Kansas using a combination of bathymetric surveying and sediment coring. Specific objectives of the studies were to: (1) estimate total sediment volume and mass; (2) estimate annual sediment deposition and yield; (3) determine occurrence and trends of constituents; (4) estimate annual constituent loads and yields; (5) assess sediment quality; and (6) provide a baseline for future assessments.

Results indicated that decreases in water-storage capacity due to sedimentation ranged from less than 5 percent at Hillsdale Lake in northeast Kansas and Webster Reservoir in north-central Kansas to about 50 percent at Cedar Lake, a small impoundment in northeast Kansas. Decreases in capacity at Cheney Reservoir (south-central Kansas), Perry Lake (northeast Kansas), and Tuttle Creek Lake (northeast Kansas) were in the range of 20 to 35 percent. Sedimentation has decreased the water-storage capacity of the large Federal reservoirs at an average annual rate of less than 1 percent, which is less than expected given a 100-year design life. Mean annual net sediment yield ranged from 0.03 (acre-ft/miî)/yr for Webster Reservoir to 1.59 (acre-ft/miî)/yr for Perry Lake. Mean annual net phosphorus yields, which paralleled the sediment yields, ranged from 26 lb/miî/yr for Webster Reservoir to 2,999 lb/miî/yr for Perry Lake.

Sediment quality was assessed on the basis of guidelines established by the U.S. Environmental Protection Agency (USEPA). Results from most of the reservoirs studied indicated that arsenic, copper, and nickel typically were detected at concentrations that exceeded USEPA threshold-effects levels. Concentrations greater than the threshold-effects levels occasionally produce adverse biological effects. At Perry Lake, nickel concentrations also typically exceeded the USEPA probable-effects level, which represents the concentration above which adverse biological effects usually or frequently occur. Chromium, lead, and zinc were detected at concentrations that exceeded the threshold-effects levels at some of the resevoirs. Cadmium and mercury concentrations typically were less than the threshold-effects levels at all reservoirs studied. Likewise, organochlorine compounds (that is, pesticides and PCBs) either were not detected or were detected at concentrations less than the threshold-effects levels. DDE, a degradation product of DDT, had a depositional profile at Perry and Tuttle Creek Lakes that reflected the history of DDT use.

Additional information about Reservoir Sediment studies in Kansas can be found at: http://ks.water.usgs.gov/studies/ressed/

Juracek, K.E., 2002, Reservoir sedimentation in Kansas: quantity and quality [abst.], in Proceedings of the 11th Annual Kansas Hydrology Seminar, November 22, 2002, Manhattan, Kansas: American Institude of Hydrology--Kansas Section and Association of Engineering Geologists--Kansas City/Omaha Section, 1 p.