Solute geochemistry of the Snake River plain regional aquifer system, Idaho and eastern Oregon

Abstract

The Regional Aquifer-System Analysis (RASA) Program was started in 1978 following a congressional mandate to develop quantitative appraisals of the major groundwater systems of the United States. The RASA Program represents a systematic effort to study a number of the Nation's most important aquifer systems, which in aggregate underlie much of the country and which represent an important component of the Nation's total water supply. In general, the boundaries of these studies are identified by the hydrologic extent of each system and accordingly transcend the political subdivisions to which investigations have often arbitrarily been limited in the past. The broad objective for each study is to assemble geologic, hydrologic, and geochemical information, to analyze and develop an understanding of the system, and to develop predictive capabilities that will contribute to the effective management of the system. The use of computer simulation is an important element of the RASA studies, both to develop an understanding of the natural, undisturbed hydrologic system and the changes brought about in it by human activities, and to provide a means of predicting the regional effects of future pumping or other stresses. The final interpretive results of the RASA Program are presented in a series of U.S. Geological Survey Professional Papers that describe the geology, hydrology, and geochemistry of each regional aquifer system. Each study within the RASA Program is assigned a single Professional Paper number, and where the volume of interpretive material warrants, separate topical chapters that consider the principal elements of the investigation may be published. The series of RASA interpretive reports begins with Professional Paper 1400 and thereafter will continue in numerical sequence as the interpretive products of subsequent studies become available.

Geochemical evolution of groundwater in the Mud Lake area, Eastern Idaho, USA

“…1) area has elevated dissolved-solids concentrations, primarily from large concentrations of chloride, sodium, sulfate, and calcium (Stearns et al 1939;Robertson et al 1974;Spinazola et al 1992;Ginsbach 2013). The source of the large concentrations of chloride, sodium, sulfate, and calcium is unknown (Olmstead 1962;Robertson et al 1974), although proposed sources include solution of continuous fallout of NaCl from the atmosphere, evaporation, infiltration of irrigation water, leaching of NaCl from the soil horizon, solution of evaporite deposits, inputs of HCl and H 2 SO 4 , inflow of thermal water, flushing of grain boundaries and pores from marine sediments, dissolution of fluid inclusion NaCl from basalt, and water-rock interaction with rhyolite and andesite (Robertson et al 1974;Wood and Low 1988;Schramke et al 1996;Busenberg et al 2001;Ginsbach 2013).…”

Results of 2001 Groundwater Sampling in Support of Conditional No Longer Contained-In Determination for the Snake River Plain Aquifer in the Vicinity of the Idaho Nuclear Technology and Engineering Center

“…In general, background levels of arsenic in the SRPA are normally reported in the 2 to 3 µg/L range (Knobel, Orr, and Cecil 1992). However, sampling in 1989 detected concentrations of arsenic in the Magic Valley and Mud Lake areas that ranged from 1 to 5 µg/L (Knobel, Orr, and Cecil 1992), and previous sampling efforts detected concentrations of arsenic in 35 of 37 water samples collected from the SRPA that ranged from 1 to 21 µg/L (Wood and Low 1988). Additionally, arsenic was detected in the upgradient indicator well, USGS-121, in October 2000 at concentrations in excess of the PRGs (Rugg 2001a).…”

Ambient water quality in aquifers used for drinking-water supplies, Gem County, southwestern Idaho, 2015

“…2 and 4B). Arsenic, like fluoride, is naturally occurring, and elevated concentrations are found throughout the Snake River Plain aquifer system and also in geothermal water (Wood and Low, 1988). Arsenic exists in several oxidation states, each of which is mobile under certain redox conditions.…”