Evaluating Geothermal Groundwater Levels to Support Bruneau Hot Springsnail Recovery

Science Center Objects

The endangered Bruneau hot springsnail (Pyrgulopsis bruneauensis) exists only in a geographically limited habitat of thermal springs and seeps in southwestern Idaho. As a part of its 2002 recovery plan for the springsnail, the U.S. Fish and Wildlife Service (USFWS) targeted conservation efforts to increase groundwater levels in the Bruneau area to protect the geothermal spring discharges necessary for the springsnail to survive.

In cooperation with the USFWS, we conducted a series of studies between 1987 and 1992 to better understand groundwater movement and groundwater levels within the area’s aquifers. In 2010, the USFWS asked us to reevaluate the effect of withdrawals from the geothermal aquifer system.

For this effort, we conducted a two-part study to 1) analyze trends in groundwater levels from 1990 to 2010, and to 2) simulate drawdown effects, using the Theis equation, of long-term groundwater pumping.

The USFWS will use the results of this study to determine if purchasing and retiring groundwater rights is effective in helping to protect and restore the critical springsnail habitat.

  • Slopes of the trend of water-level declines in individual wells ranged from 0.21 to 1.01 feet per year.
  • Both historical and simulated drawdowns imply that water levels—and potentially springs and seeps—are affected by pumping.