Groundwater uranium concentrations--how high is high

Twelve groundwater samples collected from Platte River bottomlands contained from 22.1 to 257.7 μg/l U. Highest uranium levels occurred in the shallow wells downgradient from irrigated cropland, as did highest levels of TDS and NO3-N. Fourteen groundwater samples collected from the terrace contained 0.4 to 549 μg/l U. The highest uranium levels occurred in wells screened at the bottom of the Pleistocene sands and gravels. The opposite vertical trend was observed for TDS and NO3-N. In several of the wells α activity from U was considerably greater than the 15 pCi/l permissible level for total α activity. (Auth.)