Thermal water (30.0 to 72.0 degrees Celsius) is produced from 26 wells and 2 springs in the vicinity of Banbury Hot Springs near Buhl, Idaho. Thermal water is used for space heating of private residences, catfish and tropical fish production, greenhouse operation, swimming pools, and therapeutic baths. In 1979, 10 ,300 acre-feet of thermal water was utilized; heat discharged convectively from the geothermal system was about 1.1 x 107 calories per second. Decline in artesian head and discharge apparent in recorder charts from two wells may represent seasonal fluctuations or may reflect aquifer response to development of the resource. Thermal waters sampled are sodium bicarbonate in character and slightly alkaline. Mixing of a hot (72 degrees Celsius) water with local, cooler ground water can be shown from various relations between stable isotopes, chloride, and enthalpy. On the basis of concentration of trituim, age of the waters sampled is at least 100 years an perhaps more than 1,000 years. One water (33 degress Celsius) may be as young as 29 years. On the basis of silica, sodium-potassium-calcium, and sulfate-water geothermometers, best estimate of the maximum reservoir temperature for the thermal waters is between about 70 and 100 degrees Celsius.
Thermal fluids obviously related to aquifers in both rhyolite and limestone occur in the Twin Falls-Oakley area of south-central Idaho. Limestone-related waters (high calcium with low silica and fluoride) occur in the middle and upper (southern) parts of the area. Rhyolite-related waters (low calcium but high in silica and fluoride) occur in the lower (northern) part of the area. The relation of thermal fluids in Paleozoic limestone to thermal fluids in Tertiary rhyolite is unknown. Thermal fluids from limestone are dilute, so water-rock reaction in rhyolite could obliterate chemical evidence of fluid residence in a limestone. However, isotopic tracers such as {sup 206}Pb/{sup 204}Pb, {sup 207}Pb/{sup 204}Pb, {sup 208}Pb/{sup 204}Pb, and {sup 87}Sr/{sup 86}Sr might preserve evidence of fluid residence in limestone. Systematic relations between these isotopes and dissolved constituents in the water demonstrate the presence of limestone beneath most if not all of the study area and that aquifers in the limestone and rhyolite are hydrologically connected.
5 Summary 8 References cited 8 ILLUSTRATIONS 1-2.Maps showing: 1. Location of study area, Gibson Terrace, and surrounding areas 2 2. Location and identification of wells on or near the Gibson Terrace in which water levels were measured in March or April 1990 3 I 3-5.Hydrographs showing: 3
Water-level trends, net water-level changes, and major causes governing these water-level fluctuations are presented for 366 wells in the Idaho statewide observation-well network. Water-level trends were determined for 293 wells. Downward trends in 176 of these wells ranged from less than 1 foot per year to a maximum of 7 feet per year; upward trends in 90 wells ranged from less than 1 foot per year to a maximum of 6 feet per year. Trends were level (no change) in 27 wells. Net water-level changes were determined for 361 wells. Net declines in 269 of these wells ranged from less than 1 foot to a maximum of 52.65 feet; net rises in 92 wells ranged from less than 1 foot to a maximum of 25.12 feet. Significant net water-level declines and downward trends were most apparent in or near areas designated as critical ground-water areas by the Idaho Department of Water Resources. (USGS)
Concentrations of dissolved radon-222, a naturally occurring radioactive gas, are found in water in Idaho. The U.S. Geological Survey collected water samples for radon-222 analyses from 338 Idaho wells and springs during 1989-91. These water samples were collected as part of ongoing monitoring programs with the Idaho Department of Water Resources and the U.S. Department of Energy. Concentrations of dissolved radon-222 in 372 of the water samples ranged from -58{+-}30 to 5,715{+-}66 picocuries per liter; the mean and median concentrations were 446{+-}35 and 242{+-}25 picocuries per liter, respectively.
The Payette River basin, characterized by steep, rugged mountains and narrow river valleys, occupies an area of about 3 ,300 square miles in west-central Idaho. Predominant rock types in the basin include granitic rocks of the Idaho batholith and basalt flows of the Columbia River Basalt Group. Waters from thermal springs in the basin, temperatures of which range from 34 to 86 degrees Celsius, are sodium bicarbonate types and are slightly alkaline. Dissolved-solids concentrations range from 173 to 470 milligrams per liter. Reservoir temperatures determined from the sodium-potassium-calcium and silicic acid-corrected silica geothermometers range from 53 to 143 degrees Celsius. Tritium, present in concentrations between 0 and 2 tritium units, indicate sampled thermal waters are at least 100 years old and possibly more than 1,000 years old. Stable isotope data indicate it is unlikely any of the nonthermal waters sampled are representative of precipitation that recharges the thermal springs in the basin. Thermal springs discharged about 5,700 acre-feet of water in 1979. Associated convective heat flux is 1.1x10 to the 7th power calories per second. (USGS)
Selected well-inventory and water-chemistry data for 718 thermal-water wells and springs in Idaho were compiled.A total of 1,319 chemical analyses are presented.Analyses were performed at U.S. Geological Survey laboratories from 1921 through 1991.Most data are for sites in southwest and south-central parts of the State. WELL-AND SPRING-NUMBERING SYSTEMThe well-and spring-numbering system used by the U.S. Geological Survey in Idaho indicates the location of wells and springs within the official rectangular subdivision of public land, with reference to the Boise base line and Meridian.The first two segments of the number designate the township (north or south) and range (east or west).The third segment gives the section number; four letters, which indicate the 1/4 section (160-acre tract), 1/4-1/4 section (40-acre tract), 1/4-1/4-1/4 section (10-acre tract), and serial number of the well or spring within the tract.Some locations also include a 1/4-1/4-1/4-1/4 section (2 l/2-acre tract) letter within the section number.Quarter sections are designated by the letters A, B, C, and D in counterclockwise order from the northeast quarter of each section.Forty-acre, 10-acre, and 2 i/2-acre tracts within each quarter section are lettered in the same manner.Well 3S-6E-27DDD1 (fig. 1) is in the SEl/4 SE1/4SE1/4 sec.27, T. 3 S., R. 6 E., and was the first well inventoried in that tract.Springs are designated by the letter "S" following the last numeral; for example 21N-IE-23ABA1S.
This report presents June 1987 water-quality data, principally dissolved chloride and dissolved nitrite plus nitrate (as nitrogen), for water samples from 45 wells in the Murtaugh Lake area, south-central Idaho. Chloride concentrations ranged from 23 to 320 milligrams per liter; the median concentration was 70 milligrams per liter. Nitrogen concentrations ranged from less than 0.1 to 11.0 milligrams per liter; the median concentration was 3.7 milligrams per liter. Chloride concentrations in 6 samples and nitrogen concentrations in 3 samples equaled or exceeded the U.S. Environmental Protection Agency public drinking-water limits of 250 and 10 milligrams per liter, respectively.
