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| Kansas Water Science Center |
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By Teresa J. Rasmussen, Andrew C. Ziegler, and Patrick P. Rasmussen
The lower Kansas River is an important source of drinking water for hundreds of thousands of people in northeast Kansas. Constituents of concern identified by the Kansas Department of Health and Environment (KDHE) for streams in the lower Kansas River Basin include sulfate, chloride, nutrients, atrazine, bacteria, and sediment. Real-time continuous water-quality monitors were operated at three locations along the lower Kansas River from July 1999 through September 2004 to provide in-stream measurements of specific conductance, pH, water temperature, turbidity, and dissolved oxygen and to estimate concentrations for constituents of concern. Estimates of concentration and densities were combined with streamflow to calculate constituent loads and yields from January 2000 through December 2003. The Wamego monitoring site is located 44 river miles upstream from the Topeka monitoring site, which is 65 river miles upstream from the DeSoto monitoring site, which is 18 river miles upstream from where the Kansas River flows into the Missouri River. Land use in the Kansas River Basin is dominated by grassland and cropland, and streamflow is affected substantially by reservoirs.
Water quality at the three monitoring sites varied with hydrologic conditions, season, and proximity to constituent sources. Nutrient and sediment concentrations and bacteria densities were substantially larger during periods of increased streamflow, indicating important contributions from nonpoint sources in the drainage basin.
During the study period, pH remained well above the KDHE lower criterion of 6.5 standard units at all sites in all years, but exceeded the upper criterion of 8.5 standard units annually between 2 percent of the time (Wamego in 2001) and 65 percent of the time (DeSoto in 2003). The dissolved oxygen concentration was less than the minimum aquatic-life-support criterion of 5.0 milligrams per liter less than 1 percent of the time at all sites.
Dissolved solids, a measure of the dissolved material in water, exceeded 500 milligrams per liter about one-half of the time at the three Kansas River sites. Larger dissolved-solids concentrations upstream likely were a result of water inflow from the highly mineralized Smoky Hill River that is diluted by tributary flow as it moves downstream.
Concentrations of total nitrogen and total phosphorus at the three monitoring sites exceeded the ecoregion water-quality criteria suggested by the U.S. Environmental Protection Agency during the entire study period. Median nitrogen and phosphorus concentrations were similar at all three sites, and nutrient load increased moving from the upstream to downstream sites. Total nitrogen and total phosphorus yields were nearly the same from site to site indicating that nutrient sources were evenly distributed throughout the lower Kansas River Basin. About 11 percent of the total nitrogen load and 12 percent of the total phosphorus load at DeSoto during 2000–03 originated from wastewater-treatment facilities.
Escherichia coli bacteria densities were largest at the middle site, Topeka. On average, 83 percent of the annual bacteria load at DeSoto during 2000–03 occurred during 10 percent of the time, primarily in conjunction with runoff.
The average annual sediment loads at the middle and downstream monitoring sites (Topeka and DeSoto) were nearly double those at the upstream site (Wamego). The average annual sediment yield was largest at Topeka. On average, 64 percent of the annual suspended-sediment load at DeSoto during 2000–03 occurred during 10 percent of the time. Trapping of sediment by reservoirs located on contributing tributaries decreases transport of sediment and sediment-related constituents.
The average annual suspended-sediment load in the Kansas River at DeSoto during 2000–03 was estimated at 1.66 million tons. An estimated 13 percent of this load consisted of sand-size particles, so approximately 216,000 tons of sand were transported in the water column at DeSoto during the 4-year period. This estimate does not include sand transported as bedload, the quantity of which is unknown but likely is considerably larger than sand transported as suspended load. An estimated 1.4 million tons of material (90 to 95 percent sand) were removed from the Kansas River by commercial dredging operations in 2003.
Continuous water-quality monitoring provides numerous advantages to programs dealing with total maximum daily loads over traditional water-quality studies relying on discrete sampling alone. Continuous water-quality data can be used to construct duration curves that define the magnitude and frequency of water-quality conditions and possibly to differentiate between base-flow and runoff conditions. Continuous data also can be used to identify the hydrologic and seasonal conditions during which specific impairments occur. The data also can be used to help understand and quantify variability, and to identify, monitor, and evaluate changes in conditions over time. This information is important for developing and implementing total maximum daily loads and other water-quality management plans. The continuous streamflow and water-quality data and estimated concentrations, densities, and loads are available at http://ks.water.usgs.gov/Kansas/rtqw/
Rasmussen, T.J., Ziegler, A.C., and Rasmussen, P.P., 2005, Estimation of constituent concentrations, densities, loads, and yields in lower Kansas River, northeast Kansas, using regression models and continuous water-quality monitoring, January 2000 through December 2003: U.S. Geological Survey Scientific Investigations Report 2005-5165, 117 p.
A limited number of printed copies of the full report are available free from:
U.S. Geological Survey
Kansas Water Science Center
4821 Quail Crest Place
Lawrence, KS 66049
Phone: 785-842-9909
Printed reports also are available for a nominal fee from:
U.S. Geological Survey
Information Services
P.O. Box 25286
Federal Center
Denver, CO 80225
Phone: 1-888-ASK-USGS
NOTE: When ordering the report, please supply the report title and number, your name, and your mailing address. Thank you.
Teresa Rasmussen
U.S. Geological Survey
Kansas Water Science Center
4821 Quail Crest Place
Lawrence, KS 66049-3839
Telephone: (785) 832-3576
Fax: (785) 832-3500
Email: rasmuss@usgs.gov
For more information about USGS water resources studies in Kansas, visit the USGS Kansas Water Science Center home page: http://ks.water.usgs.gov
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