Publication Summary

Previous studies in the Glade Creek Watershed indicated that surface water, and possibly ground water, might be contaminated with nitrate. To test this possibility, eleven domestic and irrigation wells, one spring, and three surface water sites were sampled in 1995. These data were also used to characterize the ground-water and surface-water quality in the Glade Creek Watershed.

Previous studies in the Glade Creek Watershed indicated that surface water, and possibly ground water, might be contaminated with nitrate. To test this possibility, eleven domestic and irrigation wells, one spring, and three surface water sites were sampled in 1995. These data were also used to characterize the ground-water and surface-water quality in the Glade Creek Watershed.

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 sampling stations were sampled in May 1995 and analyzed for nitrite+nitrate, general chemistry, and primary anion/cation constituents. 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.

Based on the results, nitrate contamination is widespread in the two uppermost aquifers (Alluvial Aquifer and Saddle Mountains Basalt Aquifer) and in Glade Creek and its tributaries. Nitrate was detected in all sampling stations for the above water sources. Nitrate concentrations range from less than one milligram per liter (mg/L) to as much as 70 mg/L, seven times the maximum contaminant level for drinking water. The only known significant source of nitrate contamination in the watershed is nitrogen-based fertilizers used in the irrigated areas.

Link to EIM data for User Study ID GLADEGW