thumbnail

The hydrothermal system in central Twin Falls County, Idaho

Water-Resources Investigations Report 88-4152

Prepared in cooperation with Idaho Department of Water Resources
By:
,

Links

Abstract

Thermal water in Twin Fall County has been used for space heating, large-scale greenhouse operations, and aquaculture since the mid-1970's. More recently, increased utilization of the thermal water has caused aquifer pressures to decline. Near the city of Twin Falls, water levels in some formerly flowing thermal wells have declined to below land surface. The thermal water is principally in the silicic volcanic rocks of the Idavada Volcanics. Electrical resistivity soundings indicate that thickness of the rocks ranges from about 700 to 3,000 ft and averages about 2,000 ft. Temperatures of water sampled range from 26 C to nearly 50 C in wells completed in the upper part of the reservoir near Twin Falls. Water from deeper parts of the reservoir may be warmer than 50 C. Most of the thermal water is a sodium bicarbonate type. The maximum fluoride concentration was 22 mg/L. Chloride concentrations between about 50 and 150 mg/L are the result of mixing of deep water with shallower, cooler water that has been affected by percolation of irrigation water. Carbon-14 concentrations in selected thermal water samples indicate ages of 1,000 to 15,000 years. The water becomes progressively older northward along proposed groundwater flowpaths. On the basis of transit times in the system of 10,000 to 15,000 years and the reservoir volume, recharge is estimated to be about 5 to 7 cu ft/sec. Net heat flux in the area is about 2.2 heat flow units.

Geospatial Extents

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
The hydrothermal system in central Twin Falls County, Idaho
Series title:
Water-Resources Investigations Report
Series number:
88-4152
Year Published:
1989
Language:
English
Publisher:
U.S. Geological Survey
Contributing office(s):
Idaho Water Science Center
Description:
iii, 44 p.,
Number of Pages:
50
Country:
United States
State:
Idaho
County:
Twin Falls County