Changes in Water Chemistry in Cedar City Irrigation System

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Coral Gardner and Don Long, Southern Utah University

Life Sciences

Irrigation of lawns and gardens in Cedar City, Utah is accomplished in two fundamentally different manners. In older neighborhoods, water is diverted from a natural stream (Coal Creek) into a series of canals and ditches for residential flood irrigation, compared to newer neighborhoods, which use sprinklers or similar devices from well water. The overall objective of this project is to better understand the chemical and biological changes that occur in irrigation and runoff waters in Cedar City. We are addressing the following three hypotheses. 1) Changes will be observed in water chemistry as surface water moves from Coal Creek through Cedar City. 2) Irrigation strategies influence water chemistry during periods of high precipitation. 3) Microbial community changes will be associated with differences in water chemistry. Water chemistry data including dissolved oxygen, conductivity, pH, alkalinity, dissolved organic matter and nitrate/nitrite were collected weekly at eight sites and during high precipitation events. Over the course of four months, there was a reduction in alkalinity levels among all sites. During high precipitation periods, nitrate was detected in newer neighborhoods. Dissolved oxygen and pH were at higher levels, while salinity and conductivity were lower in a reservoir site relative to irrigation canals. Future work will investigate bacterial community composition in Cedar City waters. We will isolate bacterial DNA from water samples and amplify the 16sRNA segment of DNA using the polymerase chain reaction. We will then correlate bacterial community composition to the water chemistry results described above.