Nitrogen and Phosphate in Vadose Waters in Heber Valley

Jeppson, Roland W.; ,

Nitrogen and Phosphate in Vadose Waters in Heber Valley

by Roland W. Jeppson, Utah State Univ, Logan, United States,

Document Type: Proceeding Paper

Part of: Management of Irrigation and Drainage Systems: Integrated Perspectives

Abstract:

During the last decade best management practices have been gradually implemented in Heber Valley to maintain and enhance the qualities of surface waters that flow into Deer Creek Reservoir. The Heber Valley Special Service District was created to collect and treat the wastewater from Heber City and Charleston. The treated water is used to irrigate a 369 acre 'sewer farm'. As part of the research program that is reported herein, twelve vadose-zone samplers were installed at six siTes within this sewer farm during the spring of 1988 to depths of 1 to 3 feet. Five additional samplers were installed adjacent to 2 dairy waste water lagoons. Water samplers were collected every other week (or longer periods) during the summers of two years and occasional during other seasons of the year, and these samples were analyzed for nitrogen, phosphate and other chemicals. Laboratory column leaching studies were also carried out using undisturbed samples to determine sorption properties of the soil. Modeling of the unsaturated flow within top soil of the sewer farm was used in connection with field and laboratory data to assist in evaluating nutrient amount that enter groundwater from the Heber Valley sewer farm and the dairy lagoons. The conclusion is that relatively small quantities of phosphate and modest amounts of nitrogen enter the groundwater from the sewer farm, at least during a below normal water years such as occurred during the study. The potential exist for 'flushing of nutrients' from large amounts of precipitation or farming practices that apply excessive irrigation amounts.

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