Nevada Geothermal Resources Map

Lisa Shevenell and Larry Garside

This map is a revision of previous versions and is a compilation of several databases containing various information on thermal springs, geothermal wells in the literature, geothermal wells permitted by the state of Nevada, and thermal gradient wells. Where sufficient data were available from the individual databases, all springs with a temperature of >10°C above average annual surface temperature and greater than 20°C, and those noted as warm or hot were retained in the database (see Houghton and others, 1975, for a map of mean annual surface temperatures). Wells with temperatures >10°C above average annual surface temperature, and with temperature gradients of >25°C/km were retained in the database. Thus, sites potentially useful for direct use applications (e.g., onion drying, aquaculture, spas, space heating, and gold heap leaching) are included on the map. Questionable records were eliminated from each database. The categories of thermal sites included on the map are (1) springs with temperatures <37°C or those identified as warm, (2) springs with temperatures ≥37°C or those identified as hot, (3) wells with temperatures <37°C or those identified as warm, (4) wells with temperatures ≥37°C or those identified as hot, selected thermal gradient wells as described below, and (6) geothermal wells permitted with the state of Nevada. Thermal waters encountered in mines are indicated with the well symbol.  The databases plotted on this map were obtained from the following sources:

1.   Garside (1994) (www.nbmg.unr.edu/geothermal/geochemdata/ofr94_2/ofr94-2.htm) – This dataset includes selected spring and well locations and chemical analyses for most of Nevada’s geothermal areas; an effort was made to include in the report one or two of the more reliable chemical analyses available for each area. Although this is a database of Nevada low-to moderate-temperature springs and wells, all high-temperature areas are included. The sources for this dataset are selected entries from Garside and Schilling (1979), GEOTHERM and WATSTORE.

2.   GEOTHERM (for Nevada) and other unpublished NBMG data, including locations digitized from 7.5' topographic maps (www.nbmg.unr.edu/geothermal/geochemdata/geotherm.htm) – Digitized wells and springs that were shown on the maps as warm or hot are included, as are those identified as thermal based on a record in GEOTHERM. Thermal gradients could not be calculated for many of the well records, but records were retained if the well temperature was >10°C above average annual surface temperature.

3.  WATSTORE – U.S. Geological Survey chemical data. Thermal gradients could not be calculated for many of the well records, but they were retained in the database if the well temperature was >10°C above average annual surface temperature ( www.nbmg.unr.edu/geothermal/geochemdata/USGS-NWIS data were obtained from the USGS web site in the summer of 2001; up-to-date data can be obtained from: http://waterdata.usgs.gov/nwis.

4.  Trexler and others (1983) map - Any sites not captured by the previous four databases were digitized from this map.

5.   SMU (David Blackwell; www.smu.edu/geothermal)– This dataset includes geothermal temperature and gradient data from exploration drill holes and heat flow holes. This data set is maintained by the Geothermal Lab at Southern Methodist University. Numerous records had no recorded temperatures. Where data were available for both gradient and well depth, temperatures were estimated. Where temperatures could not estimated, wells with a gradient of <50°C/km and located in alluvium, playas, landslides, or moraines were eliminated based on considerations of the variations in gradient between alluvium and bedrock expected in an area with the same heat flow (e.g., see Blackwell and Chapman, 1977). Location data for these alluvial units were taken from a digital version of the 1:500,000-scale state geologic map of Stewart and Carlson (1978).  Note, the “hot” gradient holes have gradients of ≥100ºC/km.  The subset of the data used in this map is located at: www.nbmg.unr.edu/geothermal/mapfiles/SMU-gradient.xls.

6.  USGS (John Sass; wrgis.wr.usgs.gov/open-file/of99-425/webmaps/home.html; Sass and others, 1999).  This database contains additional heat flow data for wells in Nevada. The wells in this database were processed in the same manner as those from the SMU database.  The subset of data used in this map is located at: www.nbmg.unr.edu/geothermal/mapfiles/USGS-gradient.xls

7.   Permitted Wells – This database is a list of all the geothermal wells on file at the Nevada Bureau of Mines and Geology (NBMG).  These files contain all the geothermal well information available at the Nevada Division of Minerals since they took over permitting such wells in 1985. (www.nbmg.unr.edu/geothermal/mapfiles/Permittedwells.xls). UTM locations were obtained using section information or distance from section line data provided in the permit application.  Hence, many locations are approximate.  Temperatures are not known for all wells in this database.  Not all wells have permit numbers assigned. See also www.nbmg.unr.edu/geothermal/mapfiles/nvgeowel.txt

8.   Power plant locations (unpublished data, L. Garside, R. Hess, and J. Snow) are shown separately on the map (www.nbmg.unr.edu/geothermal/mapfiles/PowerPlants.xls).

The first four databases, excluding the digitized points, were combined into one database (www.nbmg.unr.edu/geothermal/Mapfiles/Master/Master053106.xls, and an extensive effort was undertaken to verify locations and add relevant information to a combined database.  First, comparisons between the digitized points and the combined database were made to discover and correct errors, improve locations, and remove duplicates. See www.nbmg.unr.edu/geothermal/mapfiles/sitenames.xls for a list of names that sites or springs are also known as.  Each of the locations plotted on the map was verified or corrected based on comparison of the database derived map with individual topographic maps. Over 668 topographic maps were reviewed, covering lands in over 485 townships, and including over 2,430 geothermal sites.  From this extensive review, approximately 85 sites were shown on the combined database map, but not on the topographic maps, and approximately 60 sites were shown on the topographic maps, but not on the combined database map.  Numerous other discrepancies were found and noted .

Using the combined geothermal database map (the Map), a general township and range location was used for each specific site.  From this location, the associated USGS 1:24,000 topographic quadrangle sheet ("quad") with annotation of geothermal site location was reviewed to verify the number of sites and location of sites as indicated on the plotted Map.   If the number and location of sites was appropriate, it was so noted.  If there was a discrepancy in the number of sites or location of the sites between the Map and the topographic map, it was also noted. If the topographic map indicated sites which were not on the Map, a notation to add the site was made. If a site was not found on the topographic map, but it was a well rather than a spring, the location was retained in the database.  Some of the sites that had been digitized were later deleted when maps were checked because they were triangulation points on top of mountains that were named hot or warm spring, and hence, were not actually geothermal features.  Other sites were deleted because they were visited recently (summer-fall 2002) and were found to be cold (e.g., Bulletin 91 site numbers 65 and 70).

Notations were made for each site regarding its associated topographic map and location, along with discrepancies and other observations. These notations were organized into Excel spreadsheets to allow evaluation of each individual site.  Numerous corrections to the database locations were made based on these evaluations.  Although many sites were reviewed, the evaluation of topographic maps was not exhaustive.  For instance, the only topographic maps reviewed were those that appeared to be associated with the location of a plotted site on the Map.  There may be other topographic maps that were not reviewed that may have geothermal sites that were not included on the Map, although it is unlikely that there are many that fall in this category.

 In order to create a single file from which a revised map could be produced, the digitized site locations were added to the combined file, and the contents of this file further manipulated and evaluated.  Different identification numbers for any given site were assigned in each of the databases used to construct this combined file: digitized file (two numbers per site); Garside and Schilling (1979); Garside (1994); and GEOTHERM. Hence, up to five different numbers had been assigned to any particular, individual site in these past studies, and these numbers were correlated between the different files to obtain one single file where one could determine which numbers corresponded to each geothermal site from each of the previous studies.  Rather than assigning numbers to sites in the current work, all areas were assigned an area name. In addition, different information was noted in each of the different files, and these data were merged into the combined file.  For instance, one file may have contained temperature, or a reference, whereas another did not. These different fields were combined into one file.  Many of the included fields were incomplete, and hence, maps were consulted to add information into the constructed file such as the name of the topographic sheet, or township, range and section in which the particular site plotted. 

Once this combined file was assembled, the Township, Range and Section (TRS) noted in the file were checked for all locations.  This was done to be sure that the reported TRS was correct for the plotted latitude and longitude.  Numerous entries were revised to reflect the correct TRS, and in many other cases, the TRS was not noted in the file, and these were located on topographic maps and the information added to the file.  Also, some sites were mis-located by a township or range; these are properly located and documented in the digital location file accompanying this map.

There were numerous unnamed springs and areas in the original files, and many sites were simply noted as hot spring or warm spring.  When these sites were located within a larger area such as the Steamboat area, no specific names were sought for those locations.  When those sites were not within a larger, known geothermal area, topographic maps were consulted and sites were informally named (e.g., hot spring near Rock Creek, etc.).  Area names were also assigned to all thermal springs and wells, largely, although not entirely, based on the area names noted in NBMG Bulletin 91 (Garside and Schilling, 1979).

Additional checking and revising was conducted with the assistance of ArcView, where all points were plotted, noting from which database the points were derived. When there were clear duplicate entries, the digitized latitude/longitude location was selected, but the rest of the data (e.g., temperature, quarter section, reference, etc.) from the original reference was retained. In cases where there was one location for an area based on the combined file, but there were several digitized locations in the file of digitized points, it was assumed that the one digitized location closest to the location in the combined file was the appropriate location, and the digitized location latitude/longitude was assigned to the entry in the combined file.

When any other site locations were questionable for any number of reasons, the original references were reviewed.  For instance, Eagle Salt Works was deleted from the map database because it is actually a cold water spring.  The reference to this site was wrong in the original reference, and the reported analysis was apparently for one of the nearby Brady’s geothermal area waters.  There were numerous other changes made by checking the original references.

As noted in previous comments, other springs were deleted from the current map based on recent field visits.  For instance, in previously published geothermal literature, one spring had been located near Hot Creek Canyon.  This spring location was deleted from the current map because the only spring near this location is Blue Jay spring, which was visited by Dick Benoit in 2002, and it was found to be cold (12ºC).

References

Blackwell, D.D., and Chapman, D.S., 1977, Interpretation of geothermal gradient and heat flow data for Basin and Range geothermal systems: Geothermal Resources Council Transactions, v. 1, p. 19-20.

Garside, L.J., 1994, Nevada low-temperature geothermal resource assessment: Nevada Bureau of Mines and Geology Open-File Report 94-2

Garside, L.J., and Schilling, J.H., 1979, Thermal waters of Nevada: Nevada Bureau of Mines and Geology Bulletin 91, 163 p.

GEOTHERM database: www.nbmg.unr.edu/geothermal/geochemdata/geotherm.htm.

Houghton, J.G., Sakamoto, C.M., and Gifford, R.O., 1975, Nevada's weather and climate: Nevada Bureau of Mines and Geology Special Publication 2, 84 p.

Sass, J.H., Priest, S.S., Blanton, A.J., Sackett, P.C., Welch, S.L., and Walters, M.A., 1999, Geothermal industry temperature profiles from the Great Basin. USGS Open-File Report 99-425, online version 1.0.wrgis.wr.usgs.gov/open-file/of99-425/webmaps/home.html

SMU (Southern Methodist University) David Blackwell database, web site: www.smu.edu/geothermal/georesou/nevada.htm.

Stewart, J.H., and Carlson, J.E., 1978, Geologic map of Nevada: U.S. Geological Survey Map, 1:500,000.

Trexler, D.T., Flynn, T., Koenig, B.A., and Ghusn, G., Jr., 1983, Geothermal Resources of Nevada: Map produced by the National Geophysical Data Center, National Oceanic and Atmospheric Administration for the Geothermal and Hydropower Technologies Division, U.S. Department of Energy.

National WATer Data STOrage and REtrieval System (WATSTORE) data for Nevada. U.S. Geological Survey. waterdata.usgs.gov/nwis

Acknowledgments

      We wish to thank the following student workers who assisted in the construction of the revised database and map by checking topographic maps, plotting and digitizing sites, identifying site names, and a variety of other tasks: Ben Delwiche, Deborah Goetz, Tamison Irwin-Joyer, Joleen Ludwig, and Scott Phillips.  We also thank Robert Cheney and Susan Tingley for their cartographic work and contributions.