Selected ground-water quality data for the area near Fort Hall, Fort Hall Indian Reservation, southeastern Idaho, June 1989

The areal extent of anomalously high dissolved nitrogen concentrations in groundwater near Fort Hall on the Fort Hall Indian Reservation, Idaho is shown on a map. The study area includes that part of the reservation west of the Fort Hall Main Canal in townships 3, 4, and 5 south, ranges 34 and 35 east. Onsite determinations of specific conductance, pH, water temperature, and concentrations of total alkalinity, dissolved chloride, and dissolved nitrite plus nitrate as nitrogen were made at 71 sites during June 1989. When onsite nitrite plus nitrate concentrations exceeded about 6 mg/L nitrogen, groundwater samples were collected for nitrite plus nitrate as nitrogen ammonia, and ammonia plus organic nitrogen as nitrogen analyses at the U.S. Geological Survey National Water Quality Laboratory. Selected well-inventory and water quality data and a statistical summary of selected water quality data are also presented. (USGS)