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Wood River Valley Hydrogeologic Framework

Issue

To make scientifically based water-resource decisions, elected officials, water managers, and the general public need additional information about the Wood River Valley aquifer system. A crucial part of this information is an improved understanding of the extent, thickness, and hydraulic properties of the aquifer—a hydrogeologic framework.

Alluvium composition
Alluvium composition,
photo by USGS

How the USGS Helps

In cooperation with local agencies and organizations, we developed an updated hydrogeologic framework of the Wood River Valley aquifer system including some areas that have not been assessed by previous investigators. The updated framework is based on a review and interpretation of 3,000 drilling reports, geologic maps, previous work, and geophysical surveys conducted for the study. The description of the hydrogeologic framework includes:

  • The approximate altitude of the bedrock surface that marks the lower boundary of the aquifer system and the top of Quaternary-age basalts that are part of the aquifer system
  • The occurrence of Quaternary-age coarse- and fine-grained alluvium and basalt that constitute the Wood River Valley aquifer system
  • The distribution of hydraulic conductivity within the aquifer system.

Key Findings

The hydrogeologic framework built upon the work of previous investigators using new information and techniques. Among the key findings:

  • The base and thickness of the alluvium that forms most of the aquifer was defined for the entire aquifer using well reports and geophysics; the alluvium ranges from less than a foot to about 350 ft
  • Hydraulic conductivity was estimated for 84 wells and ranges from less than 1 ft/d to 1,900 ft/d
  • New estimates of subsurface outflow from the aquifer system was estimated to be about 4,000 acre-ft/yr beneath Silver Creek and 300 acre-ft/yr beneath Stanton Crossing

Products

Bartolino, J.R. and Adkins, C.B., 2012, Hydrogeologic framework of the Wood River Valley aquifer system, south-central Idaho: U.S. Geological Survey Scientific Investigations Report 2012–5053, 46 p.