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Kansas Water Science Center

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Contact Information:
Jennifer Graham
U.S. Geological Survey
4821 Quail Crest Place
Lawrence, Kansas 66049
(785)832-3511
jlgraham@usgs.gov
This project is conducted in cooperation with:
City of Wichita

Cheney Reservoir Studies

Period of Project: 2001 - present

Study Overview

During 2001-03, the U.S. Geological Survey, in cooperation with the city of Wichita, Kansas, conducted a study to develop reliable tools to estimate the onset of cyanobacterial-related taste-and-odor occurrences in Cheney Reservoir, one of Wichita’s primary drinking-water supplies. The study combined discrete sampling with real-time continuous water-quality monitoring in an effort to relate the concentration of the taste-and-odor compound geosmin to environmental variables measured in real time (specific conductance, pH, temperature, turbidity, dissolved oxygen, and chlorophyll). Geosmin was detected in 92 percent of discrete water-quality samples (n=25), and concentrations ranged from < 3 to 113 nanograms per liter (median = 6 ng/L). Multiple regression was used to develop a relation between geosmin concentrations in discrete water samples and the real-time variables turbidity and specific conductance (r2=0.71, p<0.01, n=18), and the resulting model was used to provide hourly estimates of geosmin concentration. The model consistently indicated when geosmin concentrations would exceed the human detection limit of 10 ng/L. Real-time estimates of geosmin and the probability that concentrations will meet or exceed the human detection limit are available on the World Wide Web at http://nrtwq.usgs.gov/ks/. Ongoing studies at Cheney Reservoir will refine the relations between reservoir and inflow conditions and taste-and-odor occurrences. The city of Wichita plans to use these models, along with other variables measured in real time, to aid the management of the resource and decrease water-treatment costs.

A diverse range of physical, chemical, and biological factors may potentially limit algal growth, and no single variable stands out as an unequivocal link to cyanobacterial bloom formation. As a result, the relations between environmental variables and cyanobacterial by-products, such as taste-and-odor compounds and toxins, are invariably complex and may vary considerably over time (hours-weeks). Understanding the factors driving algal community dynamics is critical to the development of reliable models predicting the occurrence of taste-and-odor episodes. Current research in Cheney Reservoir is focused on characterizing the physicochemical, hydrological, and biological processes in Cheney Reservoir with respect to both watershed inputs and in-reservoir processes.

Objectives

1. Assessment of annual and seasonal water-quality conditions and description of taste-and-odor and other algal-related by-products that occur in Cheney Reservoir

2. Description of the water-quality dynamics in the photosynthetic zone of the water column to provide an understanding of algal growth, diurnal movement, and production of taste-and-odor compounds associated with algae in Cheney Reservoir

3. Use of the latest technology in water-quality instrumentation to continuously monitor variability and potentially relate that information to observed algal-population dynamics and taste-and-odor episodes

4. Determination of relations between algal community structure dynamics and the production of taste-and-odor producing algal compounds (geosmin/MIB) and potential algal toxins such as microcystin

5. Providing a long-term data base with which to verify and refine previously determined relations between easily monitored water-quality variables and constituents related to the use of Cheney Reservoir as a water-supply source for the city of Wichita.

Photos of Interest

USGS Gaging Station on Cheney Lake
USGS Gaging Station on Cheney Lake
Gaging Station
Gaging Station
Gaging Station, Photo Courtesy of KDHE
Gaging Station, Photo Courtesy of KDHE
Cheney Lake, Photo Courtesy of KDHE
Cheney Lake, Photo Courtesy of KDHE
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