[en] Reconnaissance-level sampling for nine trace metals in ground water was conducted at the Idaho National Engineering Laboatory during June to November 1987. Water samples from 81 wells that tap the Snake River Plain aquifer and that are equipped with dedicated pumps were collected and analyzed for arsenic, barium, beryllium, cadmium, chromium, lead, mercury, selenium and silver; one sample from a discontinuous perched-water zone was collected with a thief sampler and analyzed for beryllium. Methods used to collect the water sample and quality assurance instituted for the sampling program are described in detail. Except for beryllium and chromium, the concentration of the trace metals in water from the 82 wells were less than their respective maximum contaminant level for drinking water established by the US Environmental Protection Agency. The maximum concentration of beryllium was 0.7 μg/L (micrograms per liter) which is near the reporting level; no maximum contamination level has been established for beryllium. The chromium concentrations in water from wells that tap the Snake River Plain aquifer ranged from less that 1 to 280 μg/L. Water from 2 of the 81 wells contained 50 μg/L or more, which is the maximum contamination level for chromium; in water from the 30 production wells, the largest chromium concentration was 20 μg/L. 13 refs., 3 figs., 2 tabs