The Reservoir was built in 1965, and there were no taste and odor problems until the early 1990's, 25 years later. The City felt that the two steps needed to improve the water quality in the reservoir were to clean up pollutants already in the reservoir, and also to reduce the amount of pollution entering the reservoir.

In 1992 the City started working with the agricultural producers in the watershed above the reservoir to reduce non-point source pollution, and that very successful program has received national recognition.

The purpose of this environmental study, A Comparative Water Quality Study of Cheney Reservoir Kansas, is to determine what conditions occur in the reservoir cause taste and odor problems, and to evaluate what techniques might be effective in eliminating those conditions.

The approach that the study team used was to collect water samples at six sites located throughout the reservoir over an 18-month period. These samples compared water chemistry, water conditions, and biological activity. The analysis of the information that was collected as led to several key findings.

Those findings include:

• The study confirmed that the taste and odor problems that have occurred in water from Cheney Reservoir are caused by the growth of blue-green algae.

• The nutrient levels in the reservoir make the reservoir eutrophic, but in other reservoirs much more severe taste and odor problems have occurred with similar water quality.

• The main nutrient that leads to the growth of algae is phosphorus, which is used as a fertilizer in the watershed.

• It appears that the high amount of suspended solids in the reservoir helps to reduce the amount of light available to algae, and helps to inhibit the growth of algae.

• There is also a correlation between the growth of algae in the reservoir and other aquatic life, and that proper fish populations (stocking) can affect the growth of blue green algae.

• If total phosphorus concentrations in the water of the reservoir are held below 110 micrograms per liter, and chlorophyll a concentration are held below 11 micrograms per liter, then there should not be a problem with taste and odor from the reservoir.

The study evaluated different alternatives that would address the level of phosphorus in the reservoir that is available for algae, and the study concludes that reducing the nutrient loading into the reservoir by changes in the watershed should be successful, and that it is the recommended method of reservoir management.

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