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Kansas Water Science Center

Sediment Quantity and Quality Issues for Kansas Reservoirs

By Kyle E. Juracek

Abstract

An understanding of the quantity and quality of sediment deposited in a reservoir is necessary for effective reservoir and watershed 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 a source of constituents to the overlying water column and biota. The U.S. Geological Survey (USGS), in cooperation with Federal, State, and local agencies, has completed 20 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 water-quality constituents, (4) estimate annual constituent loads and yields, (5) assess sediment quality with respect to available guidelines, and (6) provide a baseline for future assessments.

Results indicated that decreases in water-storage capacity due to sedimentation ranged from about 5% or less at Cheney Reservoir (south-central Kansas), Hillsdale Lake (northeast Kansas), and Webster Reservoir (north-central Kansas), to about 55% at Crystal Lake, a small impoundment in east-central Kansas. Decreases in water-storage capacity at Perry and Tuttle Creek lakes (northeast Kansas) were in the range of 20 to 35%. By 2002, sedimentation had already filled the sediment pool at Cheney Reservoir. If the historical rates of sedimentation continue, the sediment pools in Perry and Tuttle Creek lakes may be filled in by 2021 and 2023, respectively. Mean annual net sediment yield ranged from 0.03 acre-ft/mi2 for Webster Reservoir to 2.03 acre-ft/mi2 for Mound City Lake, a small impoundment in east-central Kansas. Mean annual net phosphorus yields, which paralleled the sediment yields, ranged from 26 lb/mi2 for Webster Reservoir to 2,999 lb/mi2 for Perry Lake.

Sediment quality was assessed on the basis of nonenforceable guidelines adopted by the U.S. Environmental Protection Agency (USEPA). Results from most of the reservoirs studied indicated that arsenic, chromium, 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. Cadmium, lead, and zinc were detected at concentrations that exceeded the threshold-effects levels at some of the reservoirs. Mercury and silver concentrations typically were less than the threshold-effects levels at all reservoirs studied. At Perry Lake, nickel concentrations also typically exceeded the USEPA probably-effects level, which represents the concentration above which adverse biological effects usually or frequently occur. Organochlorine compounds (that is, pesticides and PCBs)typically were not detected or were detected at concentrations less than the threshold-effects levels. DDE (a degradation product of DDT), which was detected at several reservoirs, had a sediment-deposition profile at Perry and Tuttle Creek lakes that reflected the history of DDT use.

The information provided by the reservoir sediment studies is used by the State in the development, implementation, evaluation, and revision of total maximum daily loads designed to reduce reservoir sedimentation and improve water quality. Also, the information may be used to partly reconstruct historical watershed water-quality conditions and to provide present-day baselines with which to evaluate long-term changes in reservoir sedimentation and water and sediment quality that may reflect changes in human activity in the contributing watersheds.

Juracek, K.E., 2004, Sediment quantity and quality issues for Kansas reservoirs [abs.], in 21st Annual Water and Future of Kansas Conference, March 11, 2004, Lawrence, Kansas: Manhattan, Kansas Water Resources Research Institute, p. 22.

Additional information about reservoir-sediment studies in Kansas can be found at: http://ks.water.usgs.gov/pages/reservoir-sediment

For additional information contact:

Kyle Juracek
U.S. Geological Survey
4821 Quail Crest Place
Lawrence, KS 66049-3839
Telephone: (785) 832-3527
Fax: (785) 832-3500
Email: kjuracek@usgs.gov