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ARS Home » Pacific West Area » Kimberly, Idaho » Northwest Irrigation and Soils Research » Research » Publications at this Location » Publication #295317
Title: Nutrient losses from an irrigated watershed in southern Idaho

Author
item Bjorneberg, David - Dave
item Ippolito, James
item Koehn, Anita

Submitted to: American Society of Agricultural and Biological Engineers
Publication Type: Proceedings
Publication Acceptance Date: 7/21/2013
Publication Date: 7/24/2013
Citation: Bjorneberg, D.L., Ippolito, J.A., Koehn, A.C. 2013. Nutrient losses from an irrigated watershed in southern Idaho. American Society of Agricultural and Biological Engineers, July 21-24, 2013, Kansas City, Missouri. p. 1-11.

Interpretive Summary:

Technical Abstract: Water, sediment and nutrients flowing into and out of the 82,000 ha Twin Falls, ID irrigation tract were measured from 2005 to 2008. Approximately 80% of the water flowing into the watershed was irrigation water diverted from the Snake River. About 40% of the watershed inflow returned to the Snake River. Much of this return flow was water from subsurface drain tiles and tunnels that drain shallow groundwater. Converting from furrow to sprinkler irrigation, improved irrigation management, and constructed sediment ponds have reduced sediment loss from 460 kg/ha in 1971 to <100 kg/ha in 2005. In 2007 and 2008, more sediment and phosphorus entered the watershed than returned to the Snake River. Diverting irrigation water into the watershed removed 6300 Mg of sediment, 21 Mg of dissolved P, and 32 Mg of total P from the Snake River on average each year. However, the watershed contributed almost 900 Mg of nitrate-N annually to the Snake River. Conservation practices have effectively reduced sediment and phosphorus losses from the watershed, emphasis now must shift to reducing nitrate loss from the watershed.