The Idaho National Engineering Laboratory (INEL) covers about 890 square miles of the eastern Snake River Plain, in southeastern Idaho. The eastern Snake River Plain is a structural basin which has been filled with thin basaltic lava flows, rhyolitic deposits, and interbedded sediments. These rocks form an extensive ground-water reservoir known as the Snake River Plain aquifer.
Six wells were drilled and two existing wells were deepened at the INEL from 1969 through 1974. Interpretation of data from the drilling program confirms that the subsurface is dominated by basalt flows interbedded with layers of sediment, cinders, and silicic volcanic rocks.
Water levels in the wells show cyclic seasonal fluctuations of maximum water levels in winter and minimum water levels in mid-summer. Water levels in three wells near the Big Lost River respond to changes in recharge to the Snake River Plain aquifer from the Big Lost River. Measured water levels in multiple piezometers in one well indicate increasing pressure heads with depth. A marked decline in water levels in the wells since 1977 is attributed to a lack of recharge to the Snake River Plain aquifer.
Additional publication details
USGS Numbered Series
Subsurface information from eight wells drilled at the Idaho National Engineering Laboratory, southeastern Idaho