Chemical Analyses of Ground Water in the 

Carson Desert near Stillwater, Churchill 

County, Nevada, 2005 

By DeEtta Fosbury1, Mark Walker2, and Lisa L. Stillings3

Open-File Report 2008-1201 

U.S. Department of the Interior 

U.S. Geological Survey 

 

 

1

 AMEC Earth and Environmental Inc., Portland OR 97224 

2

 University of Nevada, Natural Resources and Environmental Sciences Department, Reno, NV 89557 

3

 U.S. Geological Survey, MS176, Mackay School of Earth Science and Engineering, University of Nevada, 

Reno, NV 89557 
U.S. Department of the Interior 

DIRK KEMPTHORNE, Secretary 

U.S. Geological Survey 

Mark D. Myers, Director 

U.S. Geological Survey, Reston, Virginia 2008 

For product and ordering information: 

World Wide Web: http://www.usgs.gov/pubprod

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Suggested citation: 

Fosbury, D., Walker, M., and Stillings, L., 2008, Chemical analysis of ground water in the 

Carson Desert near Stillwater, Churchill County, Nevada, 2005: U.S. Geological Survey 

Open-File Report 2008-1201 [http://pubs.usgs.gov/of/2008/1201/]. 

Any use of trade, product, or firm names is for descriptive purposes only and does not imply 

endorsement by the U.S. Government. 

Although this report is in the public domain, permission must be secured from the individual 

copyright owners to reproduce any copyrighted material contained within this report. 

ii
Contents 

Introduction ........................................................................................................................................................5

Study area.......................................................................................................................................................5

Sampling procedures....................................................................................................................................7

Chemical data for ground water samples.....................................................................................................7

Laboratory methods ......................................................................................................................................7

Chemical data...............................................................................................................................................10

Quality assurance........................................................................................................................................10

Acknowledgments...........................................................................................................................................16

References Cited .............................................................................................................................................16

Figures 

Figure 1. Location of the study area in Churchill County, NV USA. .........................................................6 

Tables 

Table 1: Locations and depths of wells included in the study..................................................................8

Table 2: Analytical methods used by Nevada State Health Laboratory..................................................9 

Table 3: Chemical analyses of well water samples .................................................................................11 

Table 4. Quality assurance data. .................................................................................................................15 

iii
Conversion Factors 

SI to Inch/Pound 

Multiply By To obtain 

Length 

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi) 

Volume 

liter (L) 0.2642 gallon (gal) 

Mass 

milligram (mg) 3.527×10-5 ounce, avoirdupois (oz) 

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows: 

°F=(1.8×°C)+32 

Horizontal coordinate information is in the Universal Transverse Mercator Projection, Zone 11, North American 

Datum of 1983 (NAD 83) 

Altitude, as used in this report, refers to distance above the vertical datum. 

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (μS/cm at 25°C). 

Color is given in color units (CU); turbidity is given in nephelometric turbidity units (NTU). 

Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L) or micrograms per 

liter (μg/L). 

iv
5

Chemical Analyses of Groundwater in the Carson Desert near Stillwater, 

Churchill County, Nevada 

Introduction 

This report presents the chemical analyses of ground-water samples collected in 2005 from 

domestic wells located in the Stillwater area of the Carson Desert (fig. 1). These data were 

evaluated for evidence of mixing with nearby geothermal waters (Fosbury, 2007). That study used 

several methods to identify mixing zones of ground and geothermal waters using trace elements, 

chemical equilibria, water temperature, geothermometer estimates, and statistical techniques. 

In some regions, geothermal sources influence the chemical quality of ground water used 

for drinking water supplies. Typical geothermal contaminants include arsenic, mercury, antimony, 

selenium, thallium, boron, lithium, and fluoride (Webster and Nordstrom, 2003). The 

Environmental Protection Agency has established primary drinking water standards for these, with 

the exception of boron and lithium. Concentrations of some trace metals in geothermal water may 

exceed drinking water standards by several orders of magnitude. 

Geothermal influences on water quality are likely to be localized, depending on directions 

of ground water flow, the relative volumes of geothermal sources and ground water originating 

from other sources, and depth below the surface from which water is withdrawn. It is important to 

understand the areal extent of shallow mixing of geothermal water because it may have adverse 

chemical and aesthetic effects on domestic drinking water. It would be useful to understand the 

areal extent of these effects. 

Study area 

The Stillwater geothermal area is located in the Carson Desert hydrographic area in northcentral Nevada. The community of Stillwater is located about 20 km east of the city of Fallon, near 

the center of the Stillwater geothermal area (Garside and Schilling, 1979). Carson Desert is a 

hydrologically closed basin at the terminus of the Carson River basin (Figure 1). 

Four aquifers have been defined in Carson Desert, including a consolidated basalt aquifer 

and three unconsolidated, basin-fill, sedimentary aquifers. The three basin-fill, sedimentary aquifers 

are designated as shallow (0-15 m or 0-50 ft), intermediate (15-152 m or 50-500 ft), and deep 

(>152 m or >500 ft). The primary basis for these designations is water chemistry, particularly water 

hardness (Glancy, 1986). 

The principal source of recharge to the shallow basin-fill aquifers in the Stillwater area is 

upwelling water from the intermediate aquifer, and infiltration of surface water from irrigation, 

which is supplied from the Carson River and Truckee Canal. Three hundred and seventy miles of 

lined and unlined canals supply water to irrigated fields in the Carson Desert, primarily for alfalfa 

production (Lico and Seiler, 1994). Previous studies show that residents of the Carson Desert are 

exposed to high levels of trace elements in the ground water, including arsenic (As) and tungsten 

(W), which are potentially related to geothermal activity in the area (Lico and Seiler, 1994; Lico et 

al., 1987; Seiler et al., 2005; Welch and Lico, 1998). These studies have also suggested that high 
concentrations of total dissolved solids (TDS) in Stillwater well-waters are due to 

evapoconcentration of recharge water. 

Figure 1. Location of the study area in Churchill County, NV USA. 

6
Sampling procedures 

Wells in and around Stillwater were sampled once each in June and July of 2005. Table 1 

presents location and depth of wells included in the study. Well coordinates were obtained using a 

geographic positioning system (Garmin GPSmap 76S). Estimated well depths were obtained from 

interviews with well owners. 

For low temperature domestic wells (water temperature <45oC), samples were taken from 

the spigot closest to the pump and upstream of any water treatment or storage equipment. A YSI 

Multiprobe with flow-through cell was used to measure water chemical and physical properties 

(temperature, pH, specific conductance, and dissolved oxygen) in preparation for sample collection. 

Each well was purged until readings for temperature, pH, and dissolved oxygen remained constant 

for 5 minutes. The samples were not filtered. Samples for δ18O and δ2H analysis were collected in 

5-mL glass bottles and sealed with parafilm. Acidified and untreated samples were collected in 

plastic bottles provided by the Nevada State Health Laboratory. Table 2 lists methods and 

associated reporting limits. 

The YSI Multiprobe and flow-through cell could not be used with hot waters (>45oC). Hot 

domestic wells were sampled from the spigot after purging 56—75 liters and temperature remained 

constant for 5 minutes. Temperatures were measured with a hand-held thermometer. Two samples 

from a geothermal power plant (P1 and P2) were taken from valves closest to wellheads. 

Temperatures were measured by facility personnel. The open-air method of sampling at the power 

plant resulted in a great deal of steam loss from these samples, which must be considered when 

interpreting results. 

Chemical data for ground water samples 

Laboratory methods 

All sample analyses, excluding isotopes, were performed by the Nevada State Health 

Laboratory (NSHL), on the campus of the University of Nevada, Reno, in Reno, Nevada. The 

methods used for each analyte are listed in Table 2. Isotope samples (δ

18

O and δ

2

H) were analyzed 

at the University of Nevada, Reno Stable Isotope Laboratory. Water-δ

2

H analyses were performed 

using the method of Morrison et al. (2001). Water-δ

18

O analyses were performed using the CO2 - 

H2O equilibration method of Epstein and Mayeda (1953). One field blank and 4 field duplicates 

were collected and analyzed for the full suite of analytes, in order to assess for quality assurance. 

7
Table 1: Locations and depths of wells included in the study 

Well 

Designation 

UTM Zone 11 

Easting 

UTM Zone 11 

Northing Longitude Latitude 

Total Well 

Depth m (ft) 

1 367195 4375744 -118.545052 39.521083 9 (30) 

2 366536 4375907 -118.552749 39.522449 10 (33) 

3 364752 4377825 -118.573887 39.539446 15 (50) 

4 367102 4375991 -118.546183 39.523294 12 (40) 

5 366821 4375846 -118.549422 39.521944 15 (50) 

6 367087 4375912 -118.546342 39.522580 11 (35) 

7 367253 4375857 -118.544400 39.522110 11 (37) 

8 365029 4375524 -118.570198 39.518764 8 (25) 

9 362985 4374752 -118.593809 39.511487 9 (28) 

10 365762 4375064 -118.561581 39.514736 8 (25) 

11 364688 4374498 -118.573955 39.509469 310 (1017) 

12 364652 4375068 -118.574489 39.514598 9 (31) 

13 366013 4376813 -118.559014 39.530529 6 (20) 

14 365981 4376791 -118.559382 39.530325 152 (500) 

15 363809 4374817 -118.584241 39.512204 6 (20) 

16 363791 4374776 -118.584442 39.511832 10 (34) 

17 364316 4378813 -118.579161 39.548276 49 (160) 

19 357390 4372648 -118.658417 39.491627 7 (22) 

21 355647 4370785 -118.678275 39.474556 11 (36) 

22 358468 4372374 -118.645827 39.489337 6 (19) 

23 361363 4371528 -118.611999 39.482188 8 (25) 

25 355215 4370813 -118.683301 39.474736 44 (145) 

26 356533 4372041 -118.668248 39.486017 6 (20) 

27 356379 4372460 -118.670129 39.489765 6 (20) 

28 356562 4372510 -118.668012 39.490246 6 (20) 

29 356380 4372546 -118.670135 39.490540 6 (20) 

30 356440 4371273 -118.669861 39.479074 8 (25) 

32 355492 4372242 -118.680392 39.487653 6 (20) 

33 355476 4370512 -118.680203 39.472069 5 (15) 

34 358262 4372356 -118.648218 39.489141 4 (14) 

35 356267 4370770 -118.671066 39.474525 4 (13) 

36 357291 4373970 -118.659851 39.503517 8 (25) 

37 357963 4374026 -118.652050 39.504133 8 (25) 

38 366678 4377863 -118.551490 39.540090 125 (410) 

39 366725 4378334 -118.551037 39.544339 70 (230) 

40 366787 4378341 -118.550317 39.544412 6 (20) 

41 366682 4377256 -118.551321 39.534623 70 (230) 

42 363922 4372847 -118.582524 39.494478 6 (20) 

P1 366122 4378638 -118.558114 39.546984 814 (2672) 

P2 366477 4378327 -118.553921 39.544238 381 (1250) 

8
Table 2: Analytical methods used by Nevada State Health Laboratory 

Preservative Analytical 

Method 

Laboratory Reporting 

Limit Chemical Constituent 

none SM1 Alkalinity as CaC03 2320 B 20 mg/l 

15 % HNO3 (5 ml) EPA2 Antimony 200.8 1 μg/l 

Arsenic 15 % HNO3 (5 ml) EPA 200.8 3 μg/l 

Barium 15 % HNO3 (5 ml) EPA 200.7 0.02 mg/l 

Bicarbonate none SM 2320 B 25 mg/l 

Boron 15 % HNO3 (5 ml) EPA 200.7 0.5 mg/l 

Calcium 15 % HNO3 (5 ml) EPA 200.7 5 mg/l 

Carbonate none SM 2320 B 12 mg/l 

Cesium 15 % HNO3 (5 ml) EPA 200.8 1 μg/l 

Chloride none EPA 300.0 250 mg/l 

Color none SM 2120 B 3 CU 

Copper 15 % HNO3 (5 ml) EPA 200.7 0.02 mg/l 

Electrical Conductivity none SM 2510 10 μS/cm 

Fluoride none SM 4500 F C 0.2 mg/l 

Hardness 15 % HNO3 (5 ml) EPA 200.7 33 mg/l 

Hydroxide none SM 2320 B 7 mg/l 

Iron 15 % HNO3 (5 ml) EPA 200.7 0.05 mg/l 

Lithium 15 % HNO3 (5 ml) SM 3500 Li B 0.05 mg/l 

Magnesium 15 % HNO3 (5 ml) EPA 200.7 5 mg/l 

Manganese 15 % HNO3 (5 ml) EPA 200.7 0.02 mg/l 

Mercury 15 % HNO3 (5 ml) EPA 245.2 0.2 μg/l 

Nitrate + Nitrite as N 10% H2SO4 (1 ml) EPA 300.0 0.5 mg/l 

pH none EPA 150.0 n/a 

Temperature none EPA 150.0 n/a 

Potassium 15 % HNO3 (5 ml) EPA 200.7 5 mg/l 

Selenium 15 % HNO3 (5 ml) EPA 200.8 1 μg/l 

Silica (as SiO2) 15 % HNO3 (5 ml) EPA 200.7 1 mg/l 

Sodium 15 % HNO3 (5 ml) EPA 200.7 25 mg/l 

Sulfate none EPA 300.0 25 mg/l 

Thallium 15 % HNO3 (5 ml) EPA 200.8 0.5 μg/l 

Total Dissolved Solids none SM 2540 C 25 mg/l 

Tungsten 15 % HNO3 (5 ml) EPA 200.8 1 μg/l 

Turbidity none EPA 180.1 0.4 NTU 

Zinc 15 % HNO3 (5 ml) EPA 200.7 0.05 mg/l 

1

(American Public Health Association., 1998) 2

(U.S. Environmental Protection Agency) 

9
Chemical data 

Chemical data for groundwater samples are presented in Table 3. Samples numbers 1-39 

were collected from domestic water wells, while samples P1 and P2 were collected from the 

Stillwater geothermal power plant. 

Quality assurance 

Quality assurance data are presented in Table 4. Analysis of the field blank was below 

reporting levels, for all analytes. Precision of the duplicate samples was expressed as the percent 

relative standard deviation (%RSD), also called the coefficient of variation (eqn. 1; Skoog et al., 

2000). Duplicate samples generally showed a %RSD of 0-5%. 

(1)

% ×= %100

x

s RSD

Where 

s = standard deviation, and 

x = the mean of duplicate samples. 

10
11

Table 3. Chemical analyses of ground water samples. Well locations and depth are in Table 1. “<RL” = less than the reporting Sample 1 2 3 4 5 6 7 8 

Field Water Temperature (oC) 40.1 19.8 19.7 19.0 22.0 33.2 25.9 13.8 pH 7.78 8.21

17.6 18.3

8300 20005405 1360

867 281 

0.2 0.2 

5 50 5 5 7 5 7 

274 297 

8.19 8.22 8.23 8.02 8.19 7.98 

pH Temperature (oC) 17.9 18.2 19 18.4 18.1 18 

Electrical Conductivity (μS/cm) 9300 1300 5100 3000 2900 820 

Total Dissolved Solids (mg/L) 5328 881 3028 1832 1720 529 

Hardness (mg/L) 165 149 122 514 233 203 

Turbidity (NTU) 2.7 0.2 0.2 2.6 0.2 0.2 

Color (CU) 5Alkalinity as CaCO3 (mg/L) 792 319 246 352 306 189 

Antimony (μg/L) 1 <RL 2 <RL 2 3 <RL 

94 20060 1 RL <R RL R RL 

0.05 0.04

334 362 

16 2.2 

240 53 

L <R

 3

Arsenic (μg/L) 43 190 7 77 160 17 

Arsenic III (μg/L) 9 2 < L < < L < 

Barium (mg/L) 0.36 0.08 0.07 0.28 0.13 0.06 

Bicarbonate (mg/L) 966 389 300 429 373 230 

Boron (mg/L) 18 1.7 12 6.5 4.3 0.6 Calcium (mg/L) 25 40 49 140 57 55 

Carbonate (mg/L) <R L <RL <RL <RL <RL <RL <RL 

Cesium (μg/L) <RL <R 

2300 260

L <R

1.3 1.1 

L <RL <R

1.9 0.52 

65 36 

L <RL <RL <RL <RL <RL <RL 

Chloride (mg/L) 3000 170 1400 710 700 72 

Copper (mg/L) <R L 0.1 <RL <RL <RL <RL <RL Fluoride (mg/L) 0.83 1.4 4.5 0.6 1.2 0.4 

Hydroxide (mg/L) <R L <RL <RL <RL <RL <RL <RL 

Iron (mg/L) <R L 1.2 <RL 0.44 1.3 0.08 0.09 Lithium (μg/L) 1 0.31 1.7 0.68 0.61 0.1 

Magnesium (mg/L) 25 12 <RL 40 22 16 

Manganese (mg/L) 1.3 0.09

L <R

L <R

43 20 

8 2 3 1 4 2 3 <R

111 60 

1500 340

800 400 

0.13 0.07 0.05 0.66 0.05 0.16 

Mercury (μg/L) <R L <RL <RL <RL <RL <RL <RL 

Nitrate + Nitrite as N (mg/L) <R L 1.3 <RL <RL <RL <RL <RL Potassium (mg/L) 52 7 22 19 16 7 

Selenium (μg/L) LSilica (mg/L) 56 64 94 79 68 34 

Sodium (mg/L) 2000 240 1100 450 540 99 

Sulfate (mg/L) <RL 98 210 170 150 130 

Thallium (μg/L) <RL <R

12 3 5 

L <R

-11.53 -10.61

-102 -89.5

L <RL <RL <RL <RL <RL <RL 

Tungsten (μg/L) 5 2 9 8552

Zinc (mg/L) <R L <RL <RL <RL <RL <RL <RL 

δ18O (VSMOW ‰) -11.69 -10.79 -11.91 -11.03 -10.84 -8.68 

δ2H (VSMOW ‰) -104.8 -90.8 -103.7 -95.7 -93.8 -81 
12

Table 3. Chemical analyses of well water samples (continued). Sample 12 13 14 15 16 17 19 21 

Field Temp (oC) 17.0 19.4 65.0 16.0 16.1 21.612 13.8 22.5 pH (SU) 8. 29 .02 7.8 .08 .93 .01 .16 .84 

5 7 5 20 7 5 5 20 

8 8 7 8 8 7 

pH Temperature (oC) 18.5 17.6 18.3 16.9 17.6 18.9 18.7 17.8 

Electrical Conductivity (μS/cm) 630 5000 7000 820 980 7000 1100 1700 

Total Dissolved Solids (mg/L) 392 3332 4108 572 660 3988 736 1204 

Hardness (mg/L) 180 526 207 231 254 174 232 573 

Turbidity (NTU) 0.2 0.2 0.6 0.2 0.2 0.2 0.2 0.2 

Color (CU) 

Alkalinity as CaCO3 (mg/L) 176 496 100 219 198 153 255 361 

Antimony (μg/L) 2 3 RL <RL <RL <RL RL RL 

< < < 

Arsenic (μg/L) 40 370 <RL 26 19 9 15 17 

Arsenic III (μg/L) <RL 230 <RL <RL <RL 11 <RL <RL 

Barium (mg/L) 0.08 0.03 0.16 0.14 0.12 0.15 0.11 0.15 

Bicarbonate (mg/L) 213 605 122 267 241 186 311 440 

Boron (mg/L) 0.5 8.6 16 0.7 0.7 14 0.9 1.1 

Calcium (mg/L) 49 100 83 66 72 58 70 170 

Carbonate (mg/L) <RL <RL <RL <RL <RL <RL <RL <RL 

Cesium (μg/L) <RL <RL 160 <RL <RL <RL <RL <RL 

Chloride (mg/L) 52 990 2200 45 86 2300 100 190 

Copper (mg/L) <RL <RL <RL <RL <RL <RL <RL <RL 

Fluoride (mg/L) 0.7 2.2 4.5 0.6 0.3 2.4 0.4 0.4 Hydroxide (mg/L) <RL <RL <RL <RL <RL <RL <RL <RL 

Iron (mg/L) <RL <RL 0.08 <RL <RL 0.15 <RL <RL 

Lithium (μg/L) 0.1 1 1.8 0.08 0.08 1.6 0.07 0.14 

Magnesium (mg/L) 14 67 <RL 16 18 7 14 36 

Manganese (mg/L) 0.1 0.09 0.07 <RL 0.05 0.26 0.37 0.16 

Mercury (μg/L) <RL <RL <RL <RL <RL <RL <RL <RL Nitrate + Nitrite as N (mg/L) 0.6 6 <RL 8.9 9.9 <RL 1.3 16 

Potassium (mg/L) 8 31 31 10 8 22 8 <RL 

Selenium (μg/L) <RL 3 3 <RL 2 6 1 1 

Silica (mg/L) 47 68 94 39 26 56 39 39 

Sodium (mg/L) 67 930 1400 92 120 1400 160 140 

Sulfate (mg/L) 69 820 170 110 140 120 160 240 

Thallium (μg/L) <RL <RL <RL <RL <RL <RL <RL <RL 

Tungsten (μg/L) 3 4 53 1 2 34 1 1 

Zinc (mg/L) <RL <RL 0.17 <RL <RL <RL <RL <RL δ18O (VSMOW ‰) -10.2 -11.33 -12.43 -9.58 -9.41 -12.54 -10.93 -10.63 

δ2H (VSMOW ‰) -87.6 -95.8 -109.2 -84.8 -84.2 -110.6 -92.3 -89 
13

Table 3. Chemical analyses of well water samples (continued). Sample 26 27 28 29 30 32 33 34 

Field Temp (oC) 18.72 19.52 16.19 16.7 22.48 16.23 17.51 16.51 pH (SU) 8.18 8.03 8.04 8.15 8.03 8.2 8.22 8.14 

pH Temperature (oC) 20.6 21.2 20.7 20.8 21.1 21.1 20.9 20.7 

Electrical Conductivity (μS/cm) 930 1300 1800 1900 1100 980 980 1600 

Total Dissolved Solids (mg/L) 601 860 1174 1286 742 614 634 1034 

Hardness (mg/L) 311 281 390 293 340 374 307 469 

Turbidity (NTU) 0.2 0.2 0.2 0.55 0.6 0.2 0.2 0.2 

Color (CU) 5 20 15 20 15 1.5 7 5 Alkalinity as CaCO3 (mg/L) 278 330 378 422 266 177 287 264 

Antimony (μg/L) <RL <RL <RL <RL <RL <RL <RL <RL 

Arsenic (μg/L) 16 19 9 9 15 12 71 26 

Arsenic III (μg/L) <RL <RL <RL <RL <RL <RL <RL <RL Barium (mg/L) 0.19 0.14 0.1 0.03 0.16 0.09 0.04 0.21 

Bicarbonate (mg/L) 339 403 461 514 324 216 350 322 

Boron (mg/L) 0.6 1.1 1.4 1.8 0.9 0.4 0.6 0.9 

Calcium (mg/L) 95 78 110 81 100 110 80 140 

Carbonate (mg/L) <RL <RL <RL <RL <RL <RL <RL <RL 

Cesium (μg/L) <RL <RL <RL <RL <RL <RL <RL <RL 

Chloride (mg/L) 56 88 180 140 76 110 43 250 

Copper (mg/L) <RL <RL <RL <RL 0.03 <RL <RL <RL 

Fluoride (mg/L) 0.2 0.2 <RL 0.2 0.4 0.2 0.4 <RL Hydroxide (mg/L) <RL <RL <RL <RL <RL <RL <RL <RL 

Iron (mg/L) <RL <RL <RL <RL <RL <RL <RL <RL 

Lithium (μg/L) 0.09 0.1 0.11 0.12 0.1 0.07 0.14 0.1 

Magnesium (mg/L) 18 21 28 22 22 24 26 29 

Manganese (mg/L) 0.02 0.41 1.6 0.88 0.02 <RL 0.03 2.2 Mercury (μg/L) <RL <RL <RL <RL <RL <RL <RL <RL Nitrate + Nitrite as N (mg/L) 2.4 2.1 5 2.4 5.2 1.8 9.5 <RL 

Potassium (mg/L) 7 12 10 12 6 7 16 8 

Selenium (μg/L) < RL 2 RL 2 <RL 4 RL RL 

< < < 

Silica (mg/L) 32 41 30 43 34 30 36 47 

Sodium (mg/L) 85 170 250 330 120 66 95 160 

Sulfate (mg/L) 120 220 270 390 190 140 130 210 

Thallium (μg/L) <RL <RL <RL <RL <RL <RL <RL <RL Tungsten (μg/L) <RL <RL <RL <RL <RL <RL <RL 2 

Zinc (mg/L) 0.05 <RL <RL <RL 0.05 <RL <RL <RL δ18O (VSMOW ‰) -10.59 -10.93 -10.7 -10.69 -10.77 -11.48 -10.88 -10.85 

δ2H (VSMOW ‰) -89.2 -90.3 -89.7 -89.9 -90.4 -93.7 -90.5 -90.5 
14

Table 3. Chemical analyses of well water samples (continued). 

Sample 38 39 40 41 42 P1 

Field Temp (oC) 85 82 21.98 79 14.22 139.44 

pH (SU) 7.91 7.85 8.19 7.9 8.14 8.25 

pH Temperature (oC) 20.8 20.8 20.8 20.8 20.9 18.8 

Electrical Conductivity (μS/cm) 7100 7200 2300 7100 1800 8000 

Total Dissolved Solids (mg/L) 4040 4092 1542 4120 1160 4815 

Hardness (mg/L) 205 182 472 182 318 177 

Turbidity (NTU) 3.8 0.2 0.2 0.2 0.45 0.7 Color (CU) 12 7 7 5 5 5 Alkalinity as CaCO3 (mg/L) 112 131 375 103 520 58 

Antimony (μg/L) 2 2 2 <RL <RL <RL 

Arsenic (μg/L) 4 7 160 <RL 52 18 Arsenic III (μg/L) <RL 9 <RL <RL <RL 34 

Barium (mg/L) 0.2 0.24 0.09 0.18 0.05 0.08 

Bicarbonate (mg/L) 136 159 457 126 634 71 Boron (mg/L) 15 15 2 16 1.8 23 

Calcium (mg/L) 82 73 110 73 78 71 

Carbonate (mg/L) <RL <RL <RL <RL <RL <RL 

Cesium (μg/L) 170 130 <RL 170 <RL 53 Chloride (mg/L) 2200 2200 370 2200 110 2600 

Copper (mg/L) 0.02 <RL <RL <RL <RL <RL 

Fluoride (mg/L) 4.1 4.4 0.8 4.3 1.2 3.2 

Hydroxide (mg/L) <RL <RL <RL <RL <RL <RL 

Iron (mg/L) 0.66 0.11 <RL 0.1 0.15 0.55 

Lithium (μg/L) 2 2 0.38 2 0.24 3.8 

Magnesium (mg/L) <RL <RL 48 <RL 30 <RL 

Manganese (mg/L) 0.12 0.25 0.04 0.04 0.62 0.02 

Mercury (μg/L) <RL <RL <RL <RL <RL <RL 

Nitrate + Nitrite as N (mg/L) <RL <RL 3.9 <RL <RL <RL Potassium (mg/L) 28 45 21 30 9 68 

Selenium (μg/L) 4 4 4 6 <RL 5 

Silica (mg/L) 111 120 62 103 45 158 

Sodium (mg/L) 1300 1400 340 1500 290 1600 

Sulfate (mg/L) 160 150 280 170 270 180 

Thallium (μg/L) <RL <RL <RL <RL <RL 4 

Tungsten (μg/L) 56 56 3 55 <RL 47 

Zinc (mg/L) 0.06 <RL <RL <RL <RL <RL 

δ18O (VSMOW ‰) -12.5 -12.56 -10.45 -12.62 -10.41 -11.06 

δ2H (VSMOW ‰) -110.7 -110.9 -89.6 -110.7 -88.7 -104.4 
15

Table 4. Quality assurance data. “dup” = duplicate, “std dev” = standard deviation between (btwn) the sample an

Sample # 20 18 %relative 24 %relative 31 %relative 

description field blank dup of #17 std dev dup of #23 std dev dup of #30 std dev 

btwn 17&18 btwn 23&24 btwn 30&31 

Alkalinity as CaCO3 (mg/L) 2 156 1 527 0 269 1 

Antimony (μg/L) <RL <RL <RL <RL Arsenic (μg/L) <RL 9 0 170 0 15 0 

Arsenic III (μg/L) <RL 10 7 <RL <RL <RL <RL 

Barium (mg/L) <RL 0.16 5 0.13 0 0.15 5 

Bicarbonate (mg/L) <RL 190 2 643 0 328 1 Boron (mg/L) <RL 14 0 1.5 5 0.9 0 

Calcium (mg/L) <RL 59 1 160 0 98 1 

Carbonate (mg/L) <RL <RL <RL <RL <RL <RL <RL 

Cesium (μg/L) <RL <RL <RL <RL <RL <RL <RL 

Chloride (mg/L) <RL 2200 3 800 3 78 2 

Copper (mg/L) <RL <RL <RL <RL <RL 0.03 0 

Fluoride (mg/L) <RL 2.4 0 0.8 0 0.4 0 

Hydroxide (mg/L) <RL <RL <RL <RL <RL <RL <RL Iron (mg/L) <RL 0.09 35 0.05 0 0.11 <RL Lithium (μg/L) <RL 1.5 5 0.21 0 0.1 0 

Magnesium (mg/L) <RL 7 0 62 1 22 0 

Manganese (mg/L) <RL 0.26 0 <RL <RL 0.02 0 

Mercury (μg/L) <RL <RL <RL <RL <RL <RL <RL 

Nitrate+Nitrite as N (mg/L) <RL <RL <RL 0.5 13 5.1 1 

Potassium (mg/L) <RL 24 6 12 0 <RL <RL Selenium (μg/L) <RL 4 28 <RL <RL <RL <RL Silica (mg/L) <RL 58 2 53 0 34 0 

Sodium (mg/L) <RL 1400 0 490 0 110 6 

Sulfate (mg/L) <RL 110 6 160 0 190 0 

Thallium (μg/L) <RL <RL <RL <RL <RL <RL <RL Tungsten (μg/L) <RL 34 0 <RL <RL <RL <RL 

Zinc (mg/L) <RL <RL <RL <RL <RL 0.05 0 δ18O (VSMOW ‰) -12.5 0 -10.46 0 -10.76 0 

δ2H (VSMOW ‰) -110.8 0 -89.2 0 -89.8 0 
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Acknowledgments 

Dr. James Carr, University of Nevada, contributed to the sampling design. The Stable 

Isotope Laboratory at the University of Nevada, managed by Dr. Simon Poulson, provided prompt 

and thorough analyses of samples. Residents in the Stillwater area of Churchill County, NV were 

kind enough to allow us access to wells. Personnel at the Ormat geothermal power plants in 

Churchill County provided access to geothermal sources and assistance with obtaining samples. 

Finally, we thank Mike Lico and Ralph Seiler of the U.S. Geological Survey for their detailed and 

prompt reviews. This project is based upon work supported by the Cooperative State Research, 

Education, and Extension Service, U.S. Department of Agriculture, under Agreement No. [2002-

51130-01944]. Stillings’ time was supported by the U.S. Geological Survey, Mineral Resources 

Program. 

References Cited 

American Public Health Association, American Water Works Association, Water Pollution Control 

Federation, & Water Environment Federation, 1998, Standard Methods for the Examination 

of Water and Wastewater: including bottom sediments and sludges (20th ed.): Washington, 

D.C., American Public Health Association. 

Epstein, S., and Mayeda, T., 1953, Variation of O18 content of waters from natural sources: 

Geochimica et Cosmochimica Acta, v. 4, p. 213-224. 

Fosbury, D, 2007, Identifying the influences of geothermal sources on shallow aquifer water 

quality: Reno, NV, University of Nevada, Reno, M.S. thesis, 66 p. 

Garside, L.J., and Schilling, J.H., 1979, Thermal waters of Nevada: Nevada Bureau of Mines and 

Geology Bulletin 91, 168 p. 

Glancy, P.A., 1986, Geohydrology of the basalt and unconsolidated sedimentary aquifers in the 

Fallon area, Churchill County, Nevada: U.S. Geological Survey Water Supply Paper 2263, 

62 p. 

Lico, M.S., Welch, A.H., and Hughes, J.L., 1987, Geochemistry of ground water in the shallow 

alluvial aquifer, Carson Desert, western Nevada, in: Averett, R.C., and McKnight, D.M., 

(eds.), Chemical Quality of Water and the Hydrologic Cycle: Chelsea, MI, Lewis 

Publishers, p. 89-109. 

Lico, M.S., and Seiler, R.L., 1994, Ground-water quality and geochemistry, Carson Desert, western 

Nevada, U.S. Geological Survey Open File Report 94-0031, 91 p. 

Morrison, J., Brockwell, T., Merren, T., Fourel, F., and Phillips, A.M., 2001, On-line highprecision stable hydrogen isotopic analyses on nanoliter water samples: Analytical 

Chemistry, v. 73, p. 3570-3575. 

Seiler, R.L., Stollenwerk, K.G., and Garbarino, J.R., 2005, Factors controlling tungsten 

concentrations in ground water, Carson Desert, Nevada:. Applied Geochemistry, v. 20, p. 

423-441. 

Skoog D.A., West D.M., Holler, F.A., and Crouch, S. R., 2000, Analytical chemistry: An 

introduction (7th ed.): Fort Worth, TX, Saunders College Pub., 773 p. 

U.S. Environmental Protection Agency, website accessed May, 2008, Clean Water Act Analytical 

Test Methods: http://www.epa.gov/waterscience/methods/
Welch, A.H., and Lico, M.S., 1998, Factors controlling As and U in shallow ground water, 

southern Carson Desert, Nevada: Applied Geochemistry, v. 13, p. 521-539. 

Webster, J.G., and Nordstrom, D.K., 2003, Geothermal arsenic; the source, transport and fate of 

arsenic in geothermal systems, in: Stollenwerk, K.G., (ed.), Arsenic in Ground Water: 

Boston, MA, Kluwer Academic Publishers, p. 101-125. 

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