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Kansas Water Science Center |
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By Patrick P. Rasmussen and Victoria G. Christensen
Large concentrations of ammonia and densities of bacteria have been detected in reaches of the Kansas River in northeast Kansas during low streamflow conditions, prompting the Kansas Department of Health and Environment (KDHE) to list these reaches as water-quality limited with respect to ammonia and fecal coliform bacteria. Sources for ammonia and bacteria in the watershed consist of wastewater-treatment facilities (WWTFs) and agricultural and urban runoff. The U.S. Geological Survey (USGS), in cooperation with KDHE, conducted an investigation of the Kansas River to characterize hydrologic and water-quality conditions and to simulate ammonia assimilative capacity and bacteria transport during low streamflow. This report characterizes the water-quality conditions, documents the calibration of a two-dimensional water-quality model, and presents results of hypothetical simulations of existing and future WWTFs discharging to the Kansas River during low streamflow.
Water samples were collected during low streamflow conditions at 50 sampling sites along and near the Kansas River between Wamego and Kansas City, Kansas, during three synoptic surveys conducted between November 2001 and August 2002. The analytical results from these samples indicated that ammonia and other nutrient concentrations and fecal coliform bacteria densities increased in the Kansas River from Wamego to Kansas City. Point sources were the primary contributors of ammonia and fecal coliform bacteria during low-flow conditions. Generally, ammonia concentrations in the Kansas River were largest at sampling sites just downstream from WWTFs. Overall, ammonia concentrations in the Kansas River, tributaries, and WWTF effluent were larger in the winter than during the summer. None of the main-stem sample concentrations exceeded the State of Kansas pH- and temperature-dependent chronic aquatic-life criteria for ammonia during the sampling periods. Other nutrients, such as total nitrogen and total phosphorus, indicated a similar, but less variable, spatial pattern along the main stem of the Kansas River, with concentrations increasing slightly downstream from major WWTFs. The temporal variance defined by the results of synoptic survey III (July 22–August 8, 2002) indicated that ammonia concentrations in the Kansas River sometimes varied daily by as much as 155 percent at a single site.
Samples analyzed for densities of fecal coliform bacteria illustrated a seasonal,
spatial, and temporal pattern slightly different from that of nutrients. Overall,
the bacteria densities measured during the summer were larger than the densities
measured in the winter. The only fecal coliform bacteria density to exceed the
former State water-quality, single-sample criteria of 2,000 col/100 mL (colonies
per 100 milliliters of water) was measured at 4,000 col/100 mL during synoptic
III (summer 2002) on the main stem of the Kansas River at Kansas City. Temporal
variability measured during synoptic survey III indicated up to a 263-percent
difference in bacteria density over a 12-day period.
Instantaneous loads of ammonia and bacteria were computed to determine primary
inputs to the Kansas River and ammonia and bacteria decay rates in the river.
The Oakland WWTF in Topeka was the largest contributor of both ammonia and bacteria
on the basis of samples collected during the three synoptic surveys, except
for fecal coliform bacteria collected during synoptic survey III when the DeSoto
WWTF was discharging the largest concentration of bacteria. The ammonia assimilative
process was about twice as effective during the summer synoptic survey than
it was during the winter survey. Decay of fecal coliform bacteria density was
less evident and appeared to have little seasonal effect on the basis of data
collected for this report. The summer low-streamflow water-quality conditions
were suitable for nitrification, algae that consume ammonia, and consequently,
decaying organic matter that consume oxygen. The consumption of dissolved oxygen
due to nitrification and decaying algae contributed to three measurements of
dissolved oxygen that were less than the State of Kansas aquatic-life-support
use criteria of 5.0 milligrams per liter.
CE–QUAL–W2, a two-dimensional, hydrodynamic and water-quality model, was used to simulate ammonia and bacteria transport in the Kansas River from Topeka to Kansas City. The model was calibrated and verified using data from the three synoptic surveys. The calibrated model successfully simulated the hydrodynamics, water temperature, dissolved oxygen, ammonia, and fecal coliform bacteria in the Kansas River. Simulated in-stream ammonia concentrations were compared to measured concentrations upstream to downstream along the Kansas River. The simulated in-stream ammonia concentrations mostly overestimated the measured values for both winter and summer, with a few exceptions. Comparisons between measured and simulated in-stream ammonia concentrations indicated ammonia assimilation was simulated more accurately in the summer than during the winter.
Four hypothetical simulations of varied effluent discharges from existing WWTFs and addition of a proposed WWTF near DeSoto were simulated to better understand future water-quality conditions in the Kansas River. Results indicated that ammonia and dissolved-oxygen concentrations in the Kansas River will decrease from the conditions observed during synoptic surveys II (February 25 through March 1, 2002) and III (July 22 through August 8, 2002) except near the proposed WWTF where concentrations of ammonia would be near or exceed criteria for waterborne species. Effects of the proposed WWTF on dissolved oxygen would result in concentrations less than the State of Kansas aquatic-life-support use criteria of 5.0 milligrams per liter for 1 to 2 miles downstream from either of the proposed sites.
Rasmussen, P.P., Christensen, V.G., 2005, Hydrologic and water-quality conditions in the Kansas River, northeast Kansas, November 2001-August 2002, and simulation of ammonia assimilative capacity and bacteria transport during low flow: U.S. Geological Survey Scientific Investigations Report 2005-5188, 111 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.
Patrick 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: pras@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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