To test this possibility, eleven domestic and irrigation wells, one spring, and three surface water sites were sampled in 1995. The Glade Creek Watershed covers 413 square miles of open, arid land in southeast Washington.
Crop production is the basis of the economy.
Dry-land wheat is the primary agricultural commodity, but irrigated areas for food crops are expanding rapidly. All wells in which nitrate was detected, as well as the spring and the sampling station at the mouth of Glade Creek, were sampled a second time in September 1995. Nitrate was detected in all sampling stations for the above water sources. The only known significant source of nitrate contamination in the watershed is nitrogen-based fertilizers used in the irrigated areas.