Prepared in cooperation with 

WASHOE COUNTY

Estimates of Natural Ground-Water Discharge and 

Characterization of Water Quality in Dry Valley, 

Washoe County, West-Central Nevada, 2002–2003

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2004–5155
(Back of Cover)
Estimates of Natural Ground-Water Discharge and 

Characterization of Water Quality in Dry Valley, 

Washoe County, West-Central Nevada, 2002–2003

By David L. Berger, Douglas K. Maurer, Thomas J. Lopes, and Keith J. Halford

U.S. GEOLOGICAL SURVEY

Carson City, Nevada

2004

Prepared in cooperation with

WASHOE COUNTY

Scientific Investigations Report 2004-5155
U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

CHARLES G. GROAT, Director

Any use of trade, product, or firm names in this publication is for descriptive

purposes only and does not imply endorsement by the U.S. Government

For additional information Copies of this report can be

contact: purchased from:

District Chief U.S. Geological Survey 

U.S. Geological Survey Information Services

333 West Nye Lane, Room 203 Building 810

Carson City, NV 89706–0866 Box 25286, Federal Center

Denver, CO 80225–0286

email: GS-W-NVpublic-info@usgs.gov

http://nevada.usgs.gov
 iii

 CONTENTS

Abstract. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Purpose and Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Geographic Setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Climate and Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Geologic Setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Structural History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Geologic Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Hydrologic Setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Surface Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Source and Movement of Ground Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Ground-Water Discharge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

Subsurface Outflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

Evapotranspiration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Discussion of Discharge Estimates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Water Quality and Geochemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

Water Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Geochemistry of Ground Water and Streams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

References Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

Appendix—Selected ground-water levels measured in wells, Dry Valley, west-central Nevada. . . . . . . . . . . . . . . . . . . . . . . .31

FIGURES

1. Map showing general location of Dry Valley, west-central Nevada. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2. Map showing geographic features of study area, distribution of geologic units and faults, and locations

of wells and springs used in this study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

3. Map showing distribution of geologic units and faults in western part of the study area. . . . . . . . . . . . . . . . . . . . . . . 8

4. Graphs showing example of borehole-geophysical and lithological logs collected from a borehole where

well sites 14, 15, and 16 are installed along the State line, Dry Valley, west-central Nevada. . . . . . . . . . . . . . . . . . . . 9

5. Graphs showing time-distance curves and resultant velocity-depth cross section for seismic-refraction

profile A-A’, Dry Valley, west-central Nevada . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

6. Graphs showing water-level fluctuations for 2002 through 2003 in selected wells in Dry Valley, west-central

Nevada. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

7. Graph showing hydrogeologic cross section B-B’ near the mouth of Dry Valley, west-central Nevada. . . . . . .17

8. Satellite imagery showing area of phreatophytic vegetation and shallow depth to ground water . . . . . . . . . . . . . 18

9. Graph showing ratios of major ion chemistry for water sampled in Dry Valley, west-central Nevada. . . . . . . . .23

10. Graph showing chloride as a function of dissolved-solids concentration, Dry Valley, west-central 

Nevada. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

11. Graph showing relation of deuterium to oxygen-18 in sampled ground water and springs in Dry Valley,

west-central Nevada. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
iv 

TABLES

1. Site number, location, well construction, and type of data available for well and spring sites, Dry Valley, 

west-central Nevada . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2. Estimates of subsurface outflow from Dry Valley, west-central Nevada . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3. Estimates of ground-water discharge by evapotranspiration in areas of phreatophytic vegetation,

Dry Valley, west-central Nevada . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4. Estimates of natural ground-water discharge from Dry Valley, west-central Nevada . . . . . . . . . . . . . . . . . . . . . . . . 19

5. Results of chemical analyses for water samples from selected well and spring sites, Dry Valley,

west-central Nevada . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

6. Comparison of selected inorganic constituents for primary and secondary drinking-water standards, 

Dry Valley, west-central Nevada . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

7. Saturation indices of calcite for ground water in Dry Valley, west-central Nevada. . . . . . . . . . . . . . . . . . . . . . . . . . . 25

CONVERSION FACTORS, VERTICAL DATUM, AND ABBREVIATED UNITS

Multiply By To obtain

acre 4,047 square meter

acre-foot (acre-ft) 0.001233 cubic hectometer

acre foot per year (acre-ft/yr) 0.001233 cubic hectometer per year

cubic foot per second (ft3/s) 0.02832 cubic meter per second

foot (ft) 0.3048 meter

foot per day (ft/d) 0.3048 meter per day

foot per second (ft/s) 0.3048 meter per second

inch (in.) 25.4 millimeter

mile (mi) 1.609 kilometer

square foot per day (ft2/d) 0.09290 meter squared per day

gallon per minute (gal/min) 0.06308 liter per second

square mile (mi2) 2.590 square kilometer

Temperature: Degrees Celsius (oC) can be converted to degrees Fahrenheit (oF) by using the formula oF = [1.8(oC)]+32. Degrees 

Fahrenheit can be converted to degrees Celsius by using the formula oC = 0.556(oF-32).

Sea level: In this report, “sea level” refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929, formerly called “Sea-Level 

Datum of 1929”), which is derived from a general adjustment of the first-order leveling networks of the United States and Canada.

Metric water-quality and geophysical units:

g/cm3, gram per cubic centimeter mGal, milliGal

μm, micrometer μS/cm, microsiemens per centimeter at 25°C

mg/L, milligram per liter mL, milliliter

permil, part per thousand

Note: English units are used throughout this report, except in instances where a measurement has no common English-unit equivalent.
Estimates of Natural Ground-Water Discharge and 

Characterization of Water Quality in Dry Valley, 

Washoe County, West-Central Nevada, 2002–2003

by David L. Berger, Douglas K. Maurer, Thomas J. Lopes, and Keith J. Halford

Abstract

The Dry Valley Hydrographic Area is being considered as 

a potential source area for additional water supplies for the 

Reno-Sparks area, which is about 25 miles south of Dry Valley. 

Current estimates of annual ground-water recharge to Dry 

Valley have a considerable range. In undeveloped valleys, such 

as Dry Valley, long-term ground-water discharge can be 

assumed the same as long-term ground-water recharge. 

Because estimating ground-water discharge has more certainty 

than estimating ground-water recharge from precipitation, the 

U.S. Geological Survey, in cooperation with Washoe County, 

began a three-year study to re-evaluate the ground-water 

resources by estimating natural ground-water discharge and 

characterize ground-water quality in Dry Valley. 

In Dry Valley, natural ground-water discharge occurs as 

subsurface outflow and by ground-water evapotranspiration. 

The amount of subsurface outflow from the upper part of Dry 

Valley to Winnemucca and Honey Lake Valleys likely is small. 

Subsurface outflow from Dry Valley westward to Long Valley, 

California was estimated using Darcy’s Law. Analysis of two 

aquifer tests show the transmissivity of poorly sorted sediments 

near the western side of Dry Valley is 1,200 to 1,500 square 

feet per day. The width of unconsolidated sediments is about 

4,000 feet between exposures of tuffaceous deposits along the 

State line, and decreases to about 1,500 feet (0.5 mile) west of 

the State line. The hydraulic gradient east and west of the State 

line ranges from 0.003 to 0.005 foot per foot. Using these 

values, subsurface outflow to Long Valley is estimated to be 

50 to 250 acre-feet per year.

Areas of ground-water evapotranspiration were field 

mapped and partitioned into zones of plant cover using relations 

derived from Landsat imagery acquired July 8, 2002. Evapotranspiration rates for each plant-cover zone were multiplied by 

the corresponding area and summed to estimate annual groundwater evapotranspiration. About 640 to 790 acre-feet per year of 

ground water is lost to evapotranspiration in Dry Valley.

Combining subsurface-outflow estimates with ground-water 

evapotranspiration estimates, total natural ground-water 

discharge from Dry Valley ranges from a minimum of about 

700 acre-feet to a maximum of about 1,000 acre-feet annually. 

Water quality in Dry Valley generally is good and primary 

drinking-water standards were not exceeded in any samples 

collected. The secondary standard for manganese was exceeded 

in three ground-water samples. One spring sample and two 

surface-water samples exceeded the secondary standard for pH. 

Dry Valley has two primary types of water chemistry that are 

distinguishable by cation ratios and related to the two volcanicrock units that make up much of the surrounding mountains. In 

addition, two secondary types of water chemistry appear to have 

evolved by evaporation of the primary water types. Ground 

water near the State line appears to be an equal mixture of the 

two primary water chemistries and has as an isotopic characteristic similar to evaporated surface water. 

Introduction

Increasing population growth in west-central Nevada has 

resulted in urban expansion to valleys generally north of the 

Reno-Sparks area (fig. 1). Although the Truckee River provides 

most of the water to the Reno-Sparks area, ground water is the 

primary source for the northern valleys. Further development in 

several of the more urbanized valleys has been limited because 

additional ground-water resources are not available. Concerns 

about the availability of good quality ground water to sustain 

continued growth has led regional water planners to look 

for additional resources in other valleys that currently are 

undeveloped.

The Dry Valley Hydrographic Area1 (HA), a valley north 

of the Reno-Sparks area, currently has little ground-water 

development and is being considered as a potential source area 

for additional water supplies. Precipitation that falls within Dry 

Valley is the primary source of ground water. A previous waterresources investigation made in the late 1960’s, estimated 

ground-water recharge to Dry Valley from precipitation to be 

1

The U.S. Geological Survey and Nevada Division of Water Resources delineated formal hydrographic areas in Nevada systematically in the late 1960’s for 

scientific and administrative purposes (Cardinalli and other, 1968; Rush, 1968). The official hydrographic-area names, numbers, and geographic boundaries continue to be used in U.S. Geological Survey scientific reports and Division of Water Resources administrative activities. Hydrographic-area boundaries generally 

coincide with drainage-area boundaries.
2 Estimates of Natural Ground-Water Discharge and Characterization of Water Quality in Dry Valley, 2002–2003

about 2,400 acre-ft/yr (Rush and Glancy, 1967, p. 20). This 

estimate was derived from a reconnaissance-level technique, 

known as the Maxey-Eakin Method, which estimates groundwater recharge as a function of fixed fractions of precipitation 

(Maxey and Eakin, 1949, p. 40–41). Rush and Glancy (1967, 

p. 20) used a 1965 revised version of the precipitation map 

developed by Hardman (1936, 1965) to estimate annual precipitation in Dry Valley to be 44,000 acre-ft. 

A statistical-topographic model used to estimate regional 

precipitation (Daly and others, 1994) indicates that annual precipitation in Dry Valley may be as much as 80,000 acre-ft and 

the resultant ground-water recharge more than 4 times the estimate of Rush and Glancy (1967). Thomas and Albright (2003), 

using the chloride mass-balance method, estimate between 

1,400 to 4,800 acre-ft/yr of ground-water recharge from precipitation in Dry Valley. Estimates of ground-water recharge based 

on the mass balance of chloride, in part, is a direct function of 

the amount of precipitation that is assumed to fall in recharge 

source areas within a ground-water basin (Dettinger, 1989). 

Thomas and Albright (2003, p. 7) estimate that nearly 66,000 

acre-ft/yr of precipitation falls in the recharge source areas in 

Dry Valley and is based on a relation between short-term, local 

precipitation data and regional, long-term precipitation data. 

Consequently, current estimates of annual ground-water 

recharge to Dry Valley have a considerable range and are a 

direct function of the particular precipitation data used in the 

recharge estimate. 

Ground-water discharge can be estimated with much more 

certainty than ground-water recharge from precipitation (Adar 

and others, 1988). Processes of natural ground-water discharge; 

evapotranspiration (ET) and subsurface outflow, typically vary 

only slightly both aerially and temporally. In contrast, groundwater recharge is unpredictable, particularly in arid and semiarid environments where recharge from precipitation is episodic 

and often of short duration. For ground-water systems in undeveloped basins, like Dry Valley, long-term average recharge 

can be assumed to approximate long-term average discharge 

(Theis, 1940, p. 277). This assumption suggests that natural 

ground-water discharge from Dry Valley can be equated to 

ground-water recharge from precipitation and that long-term 

changes in ground-water storage are negligible (Watson and 

others, 1975, p. 342).

In Nevada, ground-water withdrawals from a basin are 

limited by law to the estimate of perennial yield (NRS 533.271). 

Perennial yield is defined as “the maximum amount of natural 

discharge that can be salvaged each year over the long term 

by pumping without bringing about some undesired result” 

(Nevada State Engineer, 1974, p. 12). Previous estimates of 

ground-water discharge in Dry Valley were made by Rush and 

Glancy (1967), in their reconnaissance-level study that included 

11 valleys north of the Reno-Sparks area. Rush and Glancy 

(1967, p. 33 and 37) estimated natural ground-water discharge 

from Dry Valley to be about 2,300 acre-ft/yr as ground-water 

outflow and ET. Assuming that about half the estimated 

discharge could be salvaged, Rush and Glancy (1967, p. 49) 

estimated the perennial yield in Dry Valley to be about 

1,000 acre-ft/yr. Because no hydrologic data were available in 

Dry Valley during the investigation, their discharge estimates 

are based on assumed values of transmissivity, ground-water 

gradients, and ET rates. Ground-water quality was not assessed 

because no wells existed in Dry Valley (Rush and Glancy, 

1967). 

An updated estimate of the amount of natural groundwater discharge and evaluation of water quality will allow for 

more effective planning of the water resources in Dry Valley 

and help determine the potential of Dry Valley as a source of 

ground water for continued regional growth. In the summer of 

2002, the U.S. Geological Survey (USGS), in cooperation with 

Washoe County, began a three-year study to re-evaluate the 

ground-water resources in Dry Valley, with emphasis on estimating natural ground-water discharge.

Purpose and Scope

The purposes of this report are to present estimates of 

natural ground-water discharge and characterize the quality of 

ground water in Dry Valley. The study area includes that part 

of Dry Valley that lies entirely in Nevada. Field work began in 

July 2002 and included; seismic-refraction profiling, installation of monitoring wells and collection of borehole geophysical 

data, water-level measurements, aquifer tests, mapping of 

phreatophytic vegetation and geology, and chemical analysis 

of water sampled from wells and springs.

Ground-water discharge by outflow through the basin fill 

to Long Valley, Calif., was estimated using Darcy’s Law. The 

estimate was based on modified geologic maps of the area, 

water levels measured in 23 wells, and two aquifer tests made 

in May and July 2003. Ground-water discharge by ET was estimated using areas of mapped phreatophytic vegetation and the 

application of remote sensing techniques for deriving ET rates. 

Field mapping was enhanced using satellite imagery acquired 

July 8, 2003. 

Water quality was characterized and compared to primary 

and secondary drinking-water standards using data from 3 wells 

and 5 springs sampled from January 2002 to June 2003 and 

from other water chemistry data collected during previous studies. Constituents analyzed included major ions, trace elements, 

nutrients, dissolved solids, and isotopes of oxygen and hydrogen. The geochemistry of ground water and streams is described 

using these analyses. 

Acknowledgments

The authors express appreciation to Norman Knox who 

granted access to property and provided supplies, materials, 

and equipment for this study; also to John Lenz, and Russel 

Mendoza who granted access to their property and provided

historical information about Dry Valley. The authors also 

acknowledge the following agencies for assistance in this study; 

Washoe County Department of Water Resources, California 

Department of Water Resources, and Lassen County Department of Community Development.
Geologic Setting 3

Geographic Setting

Dry Valley is a slightly rectangular east-west trending 

basin in west-central Nevada, about 25 miles north of the 

Reno-Sparks area (fig. 1). The boundary of the hydrographic 

area, which generally coincides with the drainage-area boundary, encompasses about 82 mi2 in Washoe County, Nev., and 

about 3 mi2 in Lassen County, Calif. 

Currently, the population in Dry Valley consists of one 

part-time resident in the southwest part of the valley. The principle industry in the area is open-range cattle grazing, which is 

supported by small areas of natural meadow grass and rangeland vegetation. Near the central part of the valley floor along 

Dry Valley Creek, a small commercial gravel pit is operated 

infrequently (fig. 2). 

Dry Valley is topographically open to the west and is 

bounded on the north, east, and south by fault-controlled mountain blocks. Although a small area of Dry Valley extends into 

California, the Nevada-California State line was chosen as the 

western boundary of the study area to provide a practical location for estimating ground-water outflow (fig. 2). Dry Valley 

Creek, which drains Dry Valley, flows across the western 

boundary and is tributary to Long Valley Creek in California. 

Honey Lake, which is about 20 miles northwest of Dry Valley, 

is the terminal lake for Long Valley Creek (fig. 1). The altitude 

of the valley floor ranges from 4,430 ft above sea level, where 

Dry Valley Creek crosses the State line, to nearly 4,600 ft about 

three miles east.

The northern boundary of the study area is made up of the 

northwest-trending Fort Sage Mountains. State Line Peak, the 

highest peak in the range, reaches 7,990 ft. A small topographically closed subbasin (about 9 mi2

) referred to by Rush (1968, 

p. 18) as the Newcomb Lake Hydrographic Area completes the 

northern boundary (fig. 1). The Virginia Mountains, with altitudes approaching 8,200 ft, make up the entire eastern boundary 

and separates Dry Valley from Pyramid Lake, another terminal 

lake. Seven Lakes Mountain (about 6,000 ft) and the northern 

extension of Dogskin Mountain (about 6,600 ft) make up the 

southern boundary.

Climate and Vegetation

The principal sources of moisture to west-central Nevada 

are the Pacific Ocean and Gulf of Mexico. The most important 

source is the Pacific Ocean, which produces moisture from 

October to June; the Gulf of Mexico produces most of the 

moisture from July to mid-September (Houghton, 1969, p. 5; 

Brenner, 1974). The study area lies in the rain shadow of the 

Sierra Nevada and, as a result, has an arid to semiarid climate.

No long-term precipitation stations operate within the 

study area; however, long-term precipitation data are available 

from two weather stations near Doyle California, one station at 

Sutcliff, a small community along the western shore of Pyramid 

Lake, and one at Sand Pass, about 17 miles north of the study 

area (fig. 1; Western Regional Climate Center, 2003). Average 

annual precipitation, based on the 30-year record (1971–2000) 

at Doyle (4,240 ft) is 11.81 inches, for Doyle 4 SSE (4,390 ft) 

is 17.44 in. and for Sutcliff (4,000 ft) is 8.33 in. Average annual 

precipitation determined for Sand Pass (3,900) is 7.81 inches 

for the previous 30-year record (1961–1990). More than 

60 percent of the annual precipitation occurs during the period 

of November through March. Annual precipitation recorded at 

both Doyle stations and Sutcliff for several water years prior 

to the study and during the study (1999 through 2003) was 

between 15 and 83 percent below the 30-year average of 

1971–2000. 

Temperatures in the study area vary greatly, as is typical in 

arid to semiarid climates. Maximum summer temperatures can 

reach 100°F but normally range from 80 to 90°F. Minimum 

temperatures in the winter often can fall below 0°F, but range 

from about 22 to 30°F. The average annual growing season is 

about 140 days (Rush and Glancy, 1967, p. 7). 

The pattern of natural vegetation in Dry Valley reflects the 

general long-term distribution of precipitation, the physical and 

chemical properties of the soil, and depth to ground water. The 

sagebrush community is the principal vegetation in Dry Valley 

and covers much of the alluvial slopes adjacent to the valley 

floor. Mixed woodlands of pinyon and juniper sparsely cover 

the surrounding mountains and isolated juniper trees are scattered across the valley floor. Vegetation on the valley floor, 

where the water table is shallow, consists mostly of saltgrass 

with small isolated stands of greasewood, rabbitbrush, and big 

sagebrush. Vegetation growing in areas where the water table or 

capillary fringe above the water table is shallow and within 

reach of their root system are called phreatophytes (Meinzer, 

1927, p. 1). Phreatophytic vegetation has a limited areal extent 

in Dry Valley. Based on field mapping and satellite imagery 

acquired on July 8, 2003, phreatophytic vegetation on the valley 

floor covers about 620 acres. Riparian type vegetation found 

along stream channels and near springs and ground-water seeps 

includes cottonwood trees, willows, and a variety of shrubs and 

grasses.

Geologic Setting

The study area lies on the very western edge of the Great 

Basin region of the Basin and Range physiographic province. 

The Great Basin region is characterized by internal drainage 

and the Basin and Range province is characterized by generally 

north-south trending mountain ranges separated by valleys. 

Extensional faulting that began about 17 million years ago (Ma; 

Stewart, 1980, p. 110) produced the present day physiography. 

This faulting was caused by extension of the earth’s crust that 

uplifted the mountain blocks and down dropped the valley 

floors. Erosion of materials from the mountain blocks has partly 

filled the valleys with unconsolidated sediments which form the 

principal aquifers in the Great Basin.
4 Estimates of Natural Ground-Water Discharge and Characterization of Water Quality in Dry Valley, 2002–2003

Figure 1. General location of Dry Valley, west-central Nevada. CALIFORNIA NEVADA

CALIFORNIA

NEVADA

CALIFORNIA

NEVADA

Honey 

Lake

Pyramid 

Lake

Nevada County Nevada County evada County

Sierra County Sierra County ierra County

Plumas County Plumas County lumas County

Lassen County Lassen County Lassen CountyWashoe County Washoe County Washoe County

80

40°00'

39°45'

39°30'

40°15'

40°30'

120°30' 120°15' 120°00' 119°45' 119°30'

Base from U.S. Geological Survey digital data, 1:100,000, 1979–1982. 

Universal Transverse Mercator projection, North American Datum of 1927.

Shaded-relief base from 30-meter Digital Elevation Model; sun illumination from 

northwest at 30 degrees above horizon.

0 20 KILOMETERS

0 5 10

5 10

20 MILES

Area of figure 2 Area of figure 2 rea of figure 2

Creek

Long

Valley

Creek

Truckee Truckee Truckee 

Valley Dry

River

Sparks

Reno

Sand 

Pass

Sand 

Pass

Sand 

Pass

Honey 

Lake 

Valley

Honey 

Lake 

Valley

Honey 

Lake 

Valley

Winnemucca 

Valley

Winnemucca 

Valley

Winnemucca 

Valley

Long 

Valley

Long 

Valley

Long 

Valley

Walker Lane fault zone Walker Lane fault zone Walker Lane fault zone

Honey Lake 

fault zone

Honey Lake 

fault zone

Honey Lake 

fault zone

Sierra Nevada 

frontal fault zone

Sierra Nevada 

frontal fault zone

Sierra Nevada 

frontal fault zone

Doyle

Sutcliffe Sutcliffe utcliffe

Doyle 

4SSE

Doyle 

4SSE

Doyle 

4SSE

Las 

Vegas

Reno

San 

Francisco

Los Angeles

CALIFORNIA

NEVADA

S i e r r a N e v a d a

Pacific Ocean

MAP 

AREA

EXPLANATION

Hydrographic areas—

 Modified from Rush (1968)

Dry Valley

Fault—Modified from 

 U.S. Geological Survey 

 (2003)

Precipitation stations

Newcomb Lake

Reno-Sparks urban area
Geologic Setting 5

Figure 2. Geographic features of study area, distribution of geologic units and faults, and locations of wells and springs used in this study. NEVADA CALIFORNIA

Area of figure 3 Area of figure 3 rea of figure 3

28

DRI 6

DRI 5

DRI 4

DRI 7

DRI 1

27

DRI 3

26

8, 9, 13, 

14, 15, 16

8, 9, 13, 

14, 15, 16

8, 9, 13, 

14, 15, 16

17 18 19

DRI 2

DRI 21

5 2 7

3

6 23 12

4 10,11

21,22 20

1

DRI 15

DRI 16

DRI 17

DRI 13

DRI 12

DRI 11

DRI 9 DRI 10

24

DRI 8

DRI 14

DRI 19 DRI 20

DRI 18

25

DryValleyCreek

Long

Valley

Creek

Dry Valley Creek

Dry Valley

North

ley Creek

rth No

South

Fork

Dry Valley Creek

Fork

Dogskin Mountain Dogskin Mountain ogskin Mountain

Seven Lakes Mountain Seven Lakes Mountain even Lakes Mountain

Fort Sage Mountains Fort Sage Mountains ort Sage Mountains

State Line Peak State Line Peak tate Line Peak

Virginia Mountains Virginia Mountains irginia Mountains

EXPLANATION

Fault—Modified from U.S. Geological Survey (2003)

Gravel pit

Well sites—Number corresponds to table 1

Spring sites—Number corresponds to table 1 (DRI indicates spring data from Thomas and Albright, 2003)

Basin-fill sediments (Quaternary)—Unconsolidated to poorly consolidated interbedded clay, silt, sand, gravel, and boulders 

Lake deposits (Quaternary)—Semi-consolidated sand, silt, clay, and minor fine gravel of Lake Lahontan 

 (Grose and Mergner, 2000) 

Volcanic rocks (Tertiary)—Basalt, basaltic andesite, andesite flows, and flow breccias of Pyramid Sequence 

 (Bonham, 1969, p. 28)

Rhyolitic tuffs or Tuffaceous deposits (Tertiary)—Welded and unwelded ash-fall and ash-flow tuffs, and tuffaceous 

 sedimentary deposits (Bonham, 1969, p. 23; Grose and Mergner, 2000)

Granitic rocks (pre-Tertiary)—Undifferentiated plutonic rocks, principally biotite-hornblende granodiorite in composition 

 (Bonham, 1969, p. 8)

Area of unmapped geology

Boundary of hydrographic area—Modified from Rush (1968)

26

19

120°00' 119°52'30" 119°45'

40°00' 

39°55'

0 1 2 MILES

0 1 2 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000, 1979–1982. 

Universal Transverse Mercator projection, North American Datum of 1927.

Shaded-relief base from 30-meter Digital Elevation Model; sun illumination from 

northwest at 30 degrees above horizon. 
6 Estimates of Natural Ground-Water Discharge and Characterization of Water Quality in Dry Valley, 2002–2003

Structural History

Dry Valley HA is near the intersection of two major zones 

of faulting. One is northwest-trending strike-slip movement 

along the Walker Lane fault zone and the other is north-south 

trending normal faulting of the Sierra Nevada frontal fault zone 

(fig. 1; Bell, 1984, p. 35; Bonham, 1969, p. 52, Grose and 

Merger, 2000). Strike-slip faults typically have horizontal 

movement, whereas normal faults have vertical movement. The 

Walker Lane fault zone is a broad zone of faulting that extends 

from Las Vegas, Nev. to Honey Lake Valley, Calif. (fig. 1; 

Bonham, 1969, p. 43–45). Although large vertical displacements along the Walker Lane fault zone have been noted, the 

dominant sense of displacement has been right-lateral, strikeslip, with as much as 20 mi of displacement (Bonham, 1969, 

p. 45). The Sierra Nevada frontal fault zone extends from just 

west of the valleys north of Reno, southward to Carson Valley, 

south of Carson City, Nev. (Bell, 1984, p. 32, Grose and 

Mergner, 2000). Vertical offsets along the Sierra Nevada frontal fault zone are as great as 5,000 ft (Bonham, 1969, p. 50).

Just southwest of Dry Valley HA, northeast to north-south 

trending faults are abruptly truncated by the right-lateral northwest trending Honey Lake fault zone which is part of the 

Walker Lane fault zone, as mapped by Grose and Mergner 

(2000). Movement along the Honey Lake fault zone is active as 

shown by displacement in the Holocene Epoch, less than 10 

thousand years ago (Ka), and may have formed the sedimentary 

basin beneath the lower part of Long Valley Creek (Grose and 

Mergner, 2000). Northwest trending strike-slip faults are 

mapped near where Dry Valley Creek crosses the State line and 

continues along a zone through the center of valley (fig. 1). 

Movement along these faults also is vertical, producing the 

uplift of Dogskin Mountain (Bonham, 1969, p. 52). 

In consolidated rocks, faults may be barriers to, or conduits 

for ground-water flow (Goodwin and others, 1999, p. 1–2; 

Caine and Forster, 1999, p. 124; Antonellini and others, 1999, 

p. 24; Nelson and others, 1999, p. 69). In unconsolidated 

sediments, faults usually are barriers to ground-water flow 

(Goodwin and others, 1999, p. 27; Heynekamp and others, 

1999, p. 27). 

Geologic Units

Geologic units in Dry Valley HA have been mapped most 

recently by Grose and Mergner (2000) in California, and by 

Bonham (1969) in Nevada. The mapping in California is at a 

scale of 1:62,500, whereas the mapping in Nevada is at a scale 

of 1:250,000. Neither of the two maps cover an area about 1,000 

ft wide along the State line. Resolution of discrepancies 

between the two geologic maps and extrapolation across the 

1,000 ft wide data gap required reconnaissance mapping by the 

authors. This was accomplished by collecting samples, locating 

geologic contacts with a Global Positioning System, and using 

aerial photography. The reconnaissance mapping was done 

along the State line about 1.5 mi north and about 3 mi south 

from Dry Valley Creek (fig. 2). The reconnaissance mapping 

involved extending the contact of the rhyolitic tuff of Grose and 

Merger (2000) eastward into Nevada. The rhyolitic tuff unit as 

mapped by the authors in Nevada appear largely non-welded 

and also may include tuffaceous-sedimentary deposits. Discrepancies in geologic mapping within the mountain blocks north 

and south of this area were not resolved. Geologic units beyond 

the area of reconnaissance mapping are shown on figure 2 as 

originally mapped by Grose and Mergner (2000) and Bonham 

(1969).

The mountain blocks surrounding Dry Valley HA are 

composed of granitic rocks of pre-Cenozoic age (more than 

66 Ma), overlain by two volcanic-rock units of Tertiary age 

(1.6 to 66 Ma; Bonham, 1969, p. 52). Near Dry Valley HA 

the granitic rocks are exposed near the center of Fort Sage 

Mountains, on the southern part of Dogskin Mountain 

(Bonham, 1969, p. 52, plate 1), and on the western flank 

of Seven Lakes Mountain (Grose and Mergner, 2000). The 

granitic rocks likely are thousands of feet thick and form an 

impermeable basement to ground-water flow. 

The oldest volcanic rocks directly overlying the granitic 

rocks are rhyolitic tuffs of early to middle Miocene age, about 

23 to 28 Ma (Bonham, 1969, p. 25; Grose and Mergner, 2000). 

The ash-fall and ash-flow tuffs range from welded to nonwelded and are mapped as the Hartford Hill Rhyolite by Bonham (1969, p. 23). Both Bonham (1969, p. 23) and Grose and 

Mergner (2000) describe interbedded sandstone and conglomerate near the base of the tuffs. As mapped by Grose and 

Mergner (2000) in Calif., the tuffs form low hills on the northern and southern sides of the western part of Dry Valley HA 

(fig. 2). In Nevada, the tuffs are exposed on the flanks of the 

Fort Sage and Seven Lakes Mountains, and on the northern end 

of Dogskin Mountain (fig. 2; Bonham 1969, plate 1). Bonham 

(1969, p. 23) states the maximum thickness for the tuffs to be 

about 4,000 ft near Dogskin Mountain. Grose and Mergner 

(2000) estimate the tuffs may reach great thicknesses and 

extend into the subsurface beneath Long Valley. Based on 

exposures near the western part of Dry Valley HA, non-welded 

tuffs and tuffaceous sediments may underlie much of the valley 

floor in that area. Where welded and fractured, the tuffs and tuffaceous sediments may be capable of transmitting ground 

water. In contrast, non-welded tuffs likely are fairly impermeable to ground-water flow.

Overlying the rhyolitic tuffs are rocks informally assigned 

to the Pyramid Sequence by Bonham (1969, p. 28). The 

Pyramid Sequence consists of a complex mixture of basalt, 

basaltic andesite, andesite flows, and flow breccias. These rocks 

are interbedded with sedimentary rocks of diatomite and shale, 

rhyolitic tuffs and tuff breccias, and dacite welded tuffs (Bonham, 1969, p. 28). The Pyramid Sequence is late Miocene in 

age, ranging from 5 to 15 Ma (Bonham, 1969, p. 30). The Pyramid Sequence covers large areas of the Virginia Mountains 

and is exposed on the southern and northern flanks of the Fort 

Sage and Seven Lakes Mountains, respectively (fig. 2). Bonham (1969, p. 28 and 29) states the thickness of the unit may 

range from 2,000 to 3,000 ft. Basaltic rocks of the Pyramid 
Geologic Setting 7

Sequence form an important aquifer in the southeastern corner 

of Honey Lake Valley with a horizontal hydraulic conductivity 

of greater than 100 ft/d where fractured (Handman and others, 

1990, p. 14 and 15). 

Henry and others (2002) have completed a preliminary 

geologic map at a scale of 1:24,000 covering the southeastern 

corner of Dry Valley HA. They map the Pyramid Sequence in 

more detail than provided by the map of Bonham (1969), and 

map Tertiary tuffaceous rocks of Oligocene age (24–38 Ma). In 

addition, they provide a geologic cross section approximately 

parallel to the topographic divide between Dry Valley HA and 

Winnemucca Valley. Rocks shown to underlie the divide 

include sandstone, conglomerate, and breccia of the Pyramid 

Sequence, and tuffaceous rocks of Oligocene age. Descriptions 

of the degree of welding of the tuffaceous rocks are not provided. Basaltic and andesitic lavas of the Pyramid Sequence, 

along with the zone of faulting between Dry Valley HA and 

Winnemucca Valley, are mapped southeast of the geologic 

section.

Unconsolidated sediments beneath and along the margins 

of the floor of Dry Valley HA overlie the consolidated rocks 

previously described (figs. 2 and 3). In Nevada, Bonham (1969, 

plate 1) describes the unconsolidated sediments near the center 

of Dry Valley as stream and alluvial-fan deposits of Quaternary 

age, less than 1.6 Ma. In California, adjacent to Dry Valley 

Creek, Grose and Merger (2000) mapped Quaternary alluvium 

to extend about 0.5 mi west of the State line. West of this point 

they describe the Quaternary sediments bounding Dry Valley 

Creek as semi-consolidated lake deposits of sand and silt 

derived from Lake Lahontan.

Pluvial Lake Lahontan filled many western Nevada basins 

during the late Pleistocene, reaching high stands of about 

4,364 ft above sea level from about 130 to 180 Ka, and again 

from 12.5 to 13.5 Ka (Benson and Thompson, 1987, p. 78; 

Reheis and others, 2002, p. 54). This high-stand altitude was 

reached about 1.2 mi west of the State line near the mouth of the 

valley. More recently, Reheis and others (2002) have presented 

evidence that high stands of Lake Lahontan reached 4,593 ft 

above sea level in the middle Pleistocene, about 650 Ka. This 

altitude is reached about 2.7 mi east of the State line, extending 

into Dry Valley. The presence of Lake Lahontan in the lower 

reaches of Dry Valley produced poorly sorted sediments near its 

mouth. As the levels of Lake Lahontan rose and fell, deposition 

near the western part of Dry Valley alternated between finegrained silt and clay during high stands, and coarse-grained 

beach and stream deposits during low stands. 

Lithologic descriptions of drill cuttings from boreholes 

installed for this study note rounded cobbles, gravel, and sand 

intermixed with silt and clay throughout the upper 200 ft of 

unconsolidated sediments along the State line. Cobbles were 

noted to depths of 80 ft, and gravel to depths of 440 ft. Increasing amounts of clay were noted below depths of 200 ft. Near a 

depth of about 650 ft, drill rates decreased markedly in very stiff 

clays. These clays could be saturated, tuffaceous deposits similar to those exposed north and south of the mouth of Dry Valley.

Geophysical logs collected from the boreholes show the 

vertical distribution of interbedded coarse- and fine-grained 

sediments near the State line. Figure 4 shows an example of 

typical borehole geophysical and lithological logs collected for 

this study (borehole with well sites 14, 15, and 16). In general, 

caliper logs show the average diameter and rugosity of the 

drilled borehole. Natural-gamma logs show clay as relatively 

high activity values (counts per second) caused by naturally 

occurring radioactive clay particles. On resistivity logs, coarsegrained sand and gravel are indicated by high resistivity values 

(ohm-meters), whereas fine-grained silt and clay are indicated 

by relatively low resistivity values. The logs on figure 4 show 

sand and gravel layers alternating with clay through the upper 

200 to 250 ft of the borehole. Below that depth, sediments 

become progressively more clayey as indicated by a general 

decrease in resistivity and increase in gamma activity. However, a sand and gravel layer about 20 ft thick is indicated near 

400 ft (fig. 4), along with relatively thin stringers of sand near 

490 and 510 ft. Below this depth to 778 ft, sediments are mostly 

clay. An increase in clay decreases the effective porosity and 

permeability of the sediments (Keys, 1990, p. 20).

Seismic-refraction data were collected near the mouth of 

Dry Valley, about 1,500 ft east of the State line, in order to 

determine the vertical extent of unconsolidated sediments (fig. 

3). The seismic-refraction data initially were interpreted in the 

field from time-distance curves using the intercept-time formula (Dobrin, 1976, p. 297). Subsequent interpretations were 

guided by an inversion algorithm that uses the delay-time 

method (Barthelmes, 1946; Pakiser and Black, 1957) to obtain 

a first-approximation depth model, then enhanced by a series of 

ray-tracing iterations (Scott, 1993). The resultant velocitydepth profile (fig. 5) shows seismic velocities of 2,500 to 

6,600 ft/s, which are typical velocities for unsaturated and 

saturated unconsolidated sediments, extending to a depth of 

about 200 ft below land surface. Beneath 200 ft, seismic 

velocities are about 8,000 ft/s, more typical of saturated semiconsolidated sediments which could be representative of saturated non-welded tuffs or tuffaceous deposits (Healy and Press, 

1964, p. 347; Zohdy and others, 1974, p. 81; Berger and others, 

2001, p. 8). Minimum depths to the underlying granitic basement were computed assuming that the latest recorded traveltime was refracted from an interface with a velocity of 12,000 

to 17,000 ft/s, as representing basement velocities. Based on 

minimum-depth computations, the thickness of semi-consolidated sediments with a velocity of about 8,000 ft/s is estimated 

to be at least 800 to 1,000 ft beneath the western side of Dry 

Valley. 

The seismic-velocity change near 200 ft, approximately 

corresponds to the depth where sediments become predominantly clay as determined from the drill cuttings and borehole 

geophysical logs collected about 1,500 ft west of the seismic 

profile. This depth may correspond to the top of saturated, nonwelded tuffs or tuffaceous deposits beneath unconsolidated sediments along the State line. The increase in drill rates near a 

depth of 650 ft may have been caused by a slightly more consolidated section of the tuffaceous deposits. Alternatively, the 
8 Estimates of Natural Ground-Water Discharge and Characterization of Water Quality in Dry Valley, 2002–2003

Creek

ValleyCreek

Dry

Long

Valley

NEVADA

CALIFORNIA

4450

4470

4430

4400

4410

4380

4420

4360

B'

B

A'

A

39°57'

39°58'

120°01' 119°58' 

0 1 MILE

0 1 KILOMETER

Base from U.S. Geological Survey digital data, 1:100,000, 1979–1982. 

Universal Transverse Mercator projection, North American Datum of 1927.

Shaded-relief base from 30-meter Digital Elevation Model; sun illumination from 

northwest at 30 degrees above horizon. 

17

7

10

7

114

4

17

3

35

7

29

25

10

4418

4428

4400

4390

4407

4398 4405

4408

4405

4353

4375

4485

4430

4428

4418

25

29

EXPLANATION

Fault—Modified from U.S. Geological Survey (2003)

Basin-fill sediments (Quaternary)—Unconsolidated to poorly consolidated interbedded clay, silt, sand, gravel, and boulders 

Lake deposits (Quaternary)—Semi-consolidated sand, silt, clay, and minor fine gravel of Lake Lahontan 

 (Grose and Mergner, 2000) 

Volcanic rocks (Tertiary)—Basalt, basaltic andesite, andesite flows, and flow breccias of Pyramid Sequence 

 (Bonham, 1969, p. 28)

Rhyolitic tuffs or Tuffaceous deposits (Tertiary)—Welded and unwelded ash-fall and ash-flow tuffs, and tuffaceous 

 sedimentary deposits (Bonham, 1969, p. 23; Grose and Mergner, 2000)

Boundary of hydrographic area—Modified from Rush (1968)

Locations of seismic-refraction profile (A) and hydrogeologic cross section (B)—See figures 5 and 7

Water-level contour, January 2004—Shows altitude of water level in well screened in Quaternary sediments. 

 Contour interval is 10 feet; dashed where approximately located. Datum is sea level. 

Well sites—Location of well used as control point. 

 Upper number is water-level altitude in feet above sea level and bottom number is depth to water in feet. 

Hand-dug well sites—Location of hand-dug well used as control point. 

 Upper number is water-level altitude in feet above sea level and bottom number is depth to water in feet. 

Figure 3. Distribution of geologic units and faults in western part of study area. A-A’, locations of seismic-refraction profile; and 

B-B’, hydrogeologic cross section, and contours of ground-water levels and measured depth to ground water in unconsolidated 

Quaternary sediments, January 2004.
0

100200300400500600700800

-20 -10 0 10 20

DEPTH, IN FEET BELOW LAND SURFACE

INCHES

Caliper

50 100 150

Natural gamma

COUNTS 

PER SECOND

MINUTES 

PER FOOT

0 25 50 75 100

Resistivity

OHM-METER

0 5 10

Penetration 

rate Lithology

Figure 4. Example of borehole-geophysical and lithological logs collected from a borehole where well sites 14, 15, and 16 are installed along the State lNevada.
10 Estimates of Natural Ground-Water Discharge and Characterization of Water Quality in Dry Valley, 2002–2003

? ?

? ?

Land surface

Unconsolidated sediments (2,500 to 6,600 ft/s)

Undifferentiated, semi-consolidated sediments (8,000 ft/s)

Minimum depth estimate to granitic basement(?) (17,000 ft/s)

Minimum depth estimate to granitic basement(?) (12,000 ft/s)

3,000

3,200

3,400

3,600

3,800

4,000

4,200

4,400

4,600

0 200 400 600 800 1,000 1,200

DISTANCE, IN FEET

ALTITUDE, IN FEET 

ABOVE SEA LEVEL

50

100

150

200

250

300

0 200 400 600 800 1,000 1,200

TIME, IN MILLISECONDS

0

8,000 ft/s

8,000 ft/s

6,000 ft/s

7,000 ft/s

7,000 ft/s

2,800 ft/s

6,400 ft/s

3,900 ft/s

6,000 ft/s 6,600 ft/s

2,500 ft/s 3,300 ft/s

A A'

upper surface of the tuffaceous deposits may slope towards the 

west with their top near a depth of 650 ft near the borehole. The 

sand and gravel layers encountered at depths of 400 to 510 ft 

could be interbedded sandstone and conglomerate within the 

tuffaceous deposits noted by Bonham (1969, p. 23) and Grose 

and Mergner (2000). Regardless of the relative age and original 

lithology of the sediments, aquifer materials are poorly sorted, 

have low permeability, and largely are fine-grained below 

depths of 200 to 250 ft. The sediments become more dense 

below depths of 200 ft, about 1,500 ft east of the State line, and 

below depths of 650 ft along the State line. 

Hydrologic Setting

Surface Water

The entire drainage area (about 82 mi2) of Dry Valley is 

tributary to Dry Valley Creek whose confluence with Long Valley Creek is about 4 mi northwest of the State line in Long Valley, Calif. (fig. 1). Most streams in Dry Valley are ephemeral, 

although some streams in their upper reaches may be perennial. 

The generally rectangular pattern of the drainage system in Dry 

Valley, particularly in the upper reaches, indicates that stream 

development is structurally controlled (fig. 2; Ritter, 1982, 

p. 170–171).

Streamflow in Dry Valley Creek was ephemeral between 

July 2002 and September 2004. Streamflow observations and 

miscellaneous discharge measurements collected from Dry 

Valley Creek, about 1 mi west of the State line, indicate streamflow began near the end of October 2002 and had ceased by 

early May 2003. During this period, average streamflow was 

less than 0.5 ft3/s. Assuming an average discharge of 0.5 ft3/s 

was sustained for 7 months, a maximum of about 210 acre-ft 

of surface-water outflow from Dry Valley occurred in the 2003 

water year (October 2002 through September 2003). Precipitation in the region during the 2003 water year was about 78 percent of the long-term average, which may account for the low 

streamflow from Dry Valley. Using channel-geometry methods, Rush and Glancy (1967, p. 30) suggest that the long-term 

average annual streamflow exiting Dry Valley at the State line 

is 4,000 acre-ft/yr. 

Numerous springs and seeps occur mostly in the mountain 

blocks surrounding Dry Valley; however, the spring near the 

center of the valley (site 25; fig. 2) discharges from the basin 

fill. The proximity of a north-west trending fault just north of 

the site, indicates that spring discharge probably is fault controlled. During this study, most springs discharged less than 

2 gal/min., were stagnant, or were dry. In 2003, several springs 

that were dry or stagnate in March began discharging in June or 

July, because of precipitation in April. 

Figure 5. Time-distance curves and resultant velocity-depth cross section for seismic-refraction profile A-A’, Dry Valley, westcentral Nevada.
Hydrologic Setting 11

Source and Movement of Ground Water

All ground water in the study area originates as precipitation. Some precipitation infiltrates to recharge the ground-water 

system and some runs off as streamflow; however, most is lost 

to evaporation. The springs in the surrounding mountain blocks 

discharge ground water that is either lost to evaporation or infiltrates back into the subsurface down gradient of the spring. In 

Dry Valley, ground water moves along paths of least resistance, 

from areas of high hydraulic head in the mountain blocks, to 

areas of low hydraulic head in sediments beneath the valley 

floor. On the valley floor, much of the ground water is consumed by phreatophytic vegetation or lost directly through 

bare-soil evaporation. The remainder of the ground water flows 

westward towards Long Valley. 

Early in the study the need for additional wells near the 

mouth of Dry Valley was recognized. Eight wells were installed 

in 5 boreholes that penetrated unconsolidated sediments near 

the mouth of Dry Valley to provide data on ground-water levels, 

lithology, aquifer properties, and water quality. Sites 10 and 11 

were installed in September 2002 at shallow depths using a 

hollow-stem auger. The remaining wells were installed in 

November 2002 using mud-rotary methods to depths of 140 to 

547 ft (table 1). All wells were cased with polyvinyl-chloride 

casing with 10 to 40 ft of well screen having 0.02 inch slots. 

At two boreholes, the wells are 2-in. diameter nested piezometers, screened at different depths within the same borehole. At 

sites 8 and 9, the wells were installed to depths of 150 and 

385 ft, respectively. At sites 14, 15, and 16, the wells were 

installed to depths of 40, 250, and 547 ft, respectively. For the 

nested piezometers, bentonite grout was emplaced below, 

between, and above each well screen and 0.25-in. silica gravel 

was emplaced around the well screen. One well (site 3; fig. 2), 

was constructed with 6-in. diameter casing and well screen to 

allow installation of a 4-in. submersible pump. All wells were 

developed by air-lifting and surging. 

Existing wells in the study area consist of irrigation wells, 

domestic and stock wells, monitoring wells installed for a previous study, and several shallow hand-dug wells. Most of these 

wells and those installed for this study were surveyed to a common datum in November 2002. 

Water levels in wells near the floor of Dry Valley indicate 

ground-water flow is westward, toward Long Valley (fig. 3; 

app. 1). Water-level contours in figure 3 were developed using 

water-level data only from wells screened in the upper 100 ft of 

unconsolidated sediments. The water-table gradient increases 

from 0.003 ft/ft east of the State line to 0.005 ft/ft west of the 

State line. The increase in gradient may be caused by the combination of less permeable lake deposits to the west and a 

restriction of ground-water flow through the narrow width of 

unconsolidated sediments west of the State line (fig. 3). In addition, the non-welded rhyolitic tuffs exposed on the northern and 

southern sides of the unconsolidated sediments have a low permeability and may produce a damming effect on ground water 

upgradient (east) from the State line. The water level in site 1, 

on the northern side of Dry Valley, indicates a steep gradient, 

about 0.13 ft/ft, through rhyolitic tuff southwestward toward 

Dry Valley Creek (fig. 3). The steep gradient indicates that the 

tuffs have a low permeability and likely transmit little ground 

water.

Depth to water is less than 10 ft below land surface in wells 

near the floor of Dry Valley, and increases to 30 ft or more in 

sites 17 and 4 near the toe of the alluvial fans on the southern 

and northern sides of the valley floor (figs. 2 and 3; app. 1). 

Depth to water at site 1, near the upper contact of the rhyolitic 

tuffs is more than 100 ft. 

In the nested piezometers, water levels decrease with 

depth, indicating the potential for downward flow (app. 1). 

Dividing the difference in water levels by the distance between 

the mid-point of the screened intervals, vertical hydraulic gradients measured in sites 14–16 average about 0.02 ft/ft. Similarly 

for sites 8 and 9, the vertical hydraulic gradient is about 0.014 

ft/ft. Although the water levels indicate a potential downward 

gradient, the presence of interbedded clays indicate a low vertical hydraulic conductivity The low vertical hydraulic conductivity of the clays would impede downward ground-water flow 

at those locations near the State line. 

Water levels measured during the study show seasonal 

fluctuations are small, less than 3 ft from 2002 through 2003 

(fig. 6). Site 19 shows the greatest fluctuation, likely because it 

is near the South Fork of Dry Valley Creek and in an area of 

phreatophytic vegetation (fig. 2). Conversely, sites 4 and 12 

shows fluctuations of less than 1 ft, probably due to the greater 

distance from Dry Valley Creek and not being in an area of 

phreatophytes. Sites 3 and 11, near the center of the valley floor, 

show fluctuations of about 1.5 to 2 ft. Water levels at sites 

showing the greatest seasonal fluctuations were highest in 

Spring of 2003 after recharge from winter precipitation, and 

lowest in late summer and fall of 2003 as ground water was discharged by phreatophytic vegetation and bare-soil evaporation 

near the valley floor.

The location of northwest-trending faults indicates there 

may be potential for ground-water outflow through faulted and 

fractured basaltic rocks along the southeastern part of upper Dry 

Valley to adjacent Winnemucca Valley (fig. 1). Numerous 

springs on the northwestern end of Winnemucca Valley also 

indicate the potential for subsurface flow across the study-area 

boundary. The lack of wells for measurement of water levels on 

either side of the hydrographic-area boundary makes determination of this possibility difficult. However, the altitude of areas 

of phreatophytes in upper Dry Valley and Winnemucca Valley 

are similar, about 5,250 ft. Assuming the depth to water is similar beneath both areas of phreatophytes, there is not a significant water-table gradient between upper Dry Valley and Winnemucca Valley. This indicates that no significant groundwater outflow southeastward from upper Dry Valley takes 

place. 

Similarly, there is potential for subsurface outflow through 

faulted and fractured basaltic rocks along northwest-trending 

faults towards Honey Lake Valley, where the valley floor lies at 

an altitude of about 4,100 ft. The northwest-trending faults 

intersect the floor of Honey Lake Valley near the CaliforniaNevada State line where there are no springs or detectable areas 

of seepage. This fact indicates the lack of subsurface outflow 

from Dry Valley northwestward towards Honey Lake Valley.
Table 1. Site number, location, well construction, and type of data available for well and spring sites, Dry Valley, west-central Nevada--Contin

Site number (fig. 2) U.S. Geological Survey site designationsa Latitude (degrees, minutes, seconds) Longitude (degrees, minutes, seconds) Land surface altitude (feet above mean sea level) Well construction 

Local identification Standard identification Casing/well depth (feet) Casing/well diameter (inches) Screened interval (feet below land surface) Well sites

12

b3

45

024N018E06H001M024N018E07D001M95N24 E18 07ADAB195N24 E18 09BCBD1024N017E01F001M

395832119595901395748120004601395747119595401395743119582401395740120012601

395832395748395747395743395741

11959591200046119595411958241200126

45444382.34403.84465.84370

132

29

140350

--

686

1612

120-130

--

100-140

60-350

--

67

b

8

b9

b10

95N24 E18 08ACCC1024N018E07G001M95N24 E18 07DAAB295N24 E18 07DAAB195N24 E18 08CBAA1

395739119591401395737120001301395737119595502395737119595501395736119593501

395739395737395737395737395736

11959141200013119595511959551195935

4415.244904401.94401.94408.7

2311

150385

32

2

10

222

----

140-150375-385

22-32

b11

1213

b14b15

95N24 E1808CBAA295N24 E18 09CABB1025N018E07J001M95N24 E18 07ADCD395N24 E18 07ADCD2

395735119593401395735119582401395734119595601395734119595503395734119595502

395735395735395734395734395734

11959341195824119595611959551195955

4408.44453.14404.94404.34404.3

3235

440

40

250

22

16

22

22-3220-35

110-440

30-40

240-250

b16

171819

95N24 E18 07ADCD195N24 E18 08CCDC195N24 E18 08CDDD195N24 E18 15BBDD1

395734119595501395716119593801395711119591501395657119571601

395734395712395711365657

1195955119594011959151195716

4404.34438.044214495

547100

c20

20

2922

537-547

80-100

--

10-20

Hand-dug wells

20212223

95N24 E18 05CCCD195N24 E18 08BDDD195N24 E18 08BCBA195N24 E18 08ADAD1

395805119593801395753119593201395750119593701395745119583901

395805395753395750395745

1195938119593211959371195839

4452442144204447

41181539

NANANANA

NANANANA

Table 1. Site number, location, well construction, and type of data available for well and spring sites, Dry Valley, west-central Nevada[Abbreviations: --, no data; NA, not applicable. Available data: AT, aquifer test; DL, drillers’ log; GL, geophysical logs; QW, water chemistry; WL, ground-water leve
Spring sites

2425262728

95N24 E19 05AADB195N24 E18 15ABAC195N24 E18 17DCCD195N24 E18 26ABAC195N24 E19 28DBBB1

395846119515801395704119564501395620119590901395523119553901395516119510201

395846395704395620395523395516

11951581195645119590911955391195102

52904530485050905690

NANANANANA

NANANANANA

NANANANANA

aEach U.S. Geological Survey data-collection site is assigned a unique identification on the basis of geographic location. Wells and springs are identified by a lo

California) and a standard latitude-longitude system. For convenience, short site number (1 - 28) also are used for sites discussed in this report. In California wells are 

their location in the rectangular system for subdivision of public lands. Identification consists of the township number, north or south (N or S); the range number, east o

section number. Each section is divided into sixteen 40-acre tracts lettered consecutively (except I and O) beginning with “A” in the northeast corner of the section and prmanner to “R” in the southeast corner. Within the 40-acre tract, wells are sequentially numbered in the order they are inventoried. The final letter (M) refers to the Mou

meridian. In Nevada, a local site designation is used to identify a site by hydrographic area (Rush, 1968) and by the official rectangular subdivision of the public lands 

Diablo base line and meridian. Each site designation consists of four units. The first unit is the hydrographic area number. The second unit is the township, preceded by 

north of the base line. The third unit is the range, preceded by “E” to indicate location east of the meridian. The fourth unit consists of the section number and letters de

section, quarter-quarter section and so on (A, B, C, and D indicate the northeast, northwest, southwest, and southeast quarter, respectively), followed by a number indic

which the site was recorded.

The standard identification is based on the grid system of latitude and longitude. The number consists of 15 digits. The first six digits denote the degrees, minutes, 

the next seven digits denote the degrees, minutes, and seconds of longitude; and the last two digits (assigned sequentially) identify the sites within a 1-second grid. The ass

as a permanent identifier even if a more precise latitude and longitude are later determined.

bWell drilled as part of this study. Drilled depth: site 1, 136 ft; site 3, 141 ft; sites 8 and 9, 387 ft; site 10, 44 ft; site 11, 41 ft; site 13, 456 ft; sites 14, 15, and 16, cCollapsed at 15.1 ft.

Table 1. Site number, location, well construction, and type of data available for well and spring sites, Dry Valley, west-central Nevada--Contin

Site 

number 

(fig. 2)

U.S. Geological Survey site designationsa

Latitude 

(degrees, 

minutes, 

seconds)

Longitude 

(degrees, 

minutes, 

seconds)

Land 

surface 

altitude 

(feet 

above 

mean 

sea 

level)

Well construction

Local identification Standard identification Casing/well depth (feet) Casing/well diameter (inches)

Screened 

interval

(feet 

below land 

surface)
14 Estimates of Natural Ground-Water Discharge and Characterization of Water Quality in Dry Valley, 2002–2003

Site 2

4372

4373

4374

4375

4376

4377

4378

Site 3

4397

4398

4399

4400

4401

4402

4403

Site 11

4402

4403

4404

4405

4406

4407

4408

Site 4

4426

4427

4428

4429

4430

4431

4432

DATE

WATER LEVEL, IN FEET ABOVE SEA LEVEL

JFM

2002 2003 2004

AMJ J ASOND J FM J FM AMJ J ASOND

Figure 6. Water-level fluctuations for 2002 through 2003 in selected wells in Dry Valley, west-central Nevada.
Hydrologic Setting 15

Site 17

4401

4402

4403

4404

4405

4406

4407

Site 12

4425

4426

4427

4428

4429

4430

4431

Site 19

4478

4479

4480

4481

4482

4483

4484

WATER LEVEL, IN FEET ABOVE SEA LEVEL

DATE

JFM

2002 2003 2004

AMJ J ASOND J FM J FM AMJ J ASOND

Figure 6.—Continued.
16 Estimates of Natural Ground-Water Discharge and Characterization of Water Quality in Dry Valley, 2002–2003

Land surface

Unwelded tuffs or

tuffaceous-sedimentary 

deposits

Unwelded tuffs or

tuffaceous-sedimentary 

deposits

 sites

14–16

sites 8 and 9

site 3

Dry Valley 

Creek

Sand and gravel alternating 

with clay and silt 

Clay with silt 

and some sand

Unwelded tuffs (?)

or tuffaceous-sedimentary

deposits (?)

Sand and gravel layer

Clay and silt 

? ?

? ?

? ?

3,500

3,600

3,700

3,800

3,900

4,000

4,100

4,200

4,300

4,400

4,500

4,600

ALTITUDE, IN FEET ABOVE SEA LEVEL

0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000

DISTANCE, IN FEET ABOVE SEA LEVEL

VERTICAL EXAGGERATION X 3.3

B B'

Ground-Water Discharge

Natural ground-water discharge from Dry Valley occurs 

by subsurface outflow to Long Valley and ET by phreatophytic 

vegetation in areas of shallow ground water. Estimates of subsurface outflow are made by applying Darcy’s Law (Health, 

1989, p. 26) and using measured and estimated hydraulic properties of unconsolidated sediments through which flow takes 

place. Estimates of ET are made from the mapped distribution 

of phreatophytes and application of ET rates derived from 

remote sensing techniques developed by Nichols (2000).

Subsurface Outflow

Subsurface outflow beneath the western boundary of the 

study area can be estimated directly from Darcy’s Law using 

estimates of transmissivity, the width of unconsolidated sediments through which flow takes place, and the slope of the 

water table perpendicular to the direction of flow. Subsurface 

outflow was estimated using the following equation for Darcy’s 

Law as modified from Heath (1989, p. 26):

Q = 0.0084T W dh/dl (1)

where Q is the quantity of subsurface flow in acre-feet per 

year;

 T is the transmissivity in squared feet per day; 

 W is the width of the flow section in feet;

 dh/dl is the hydraulic gradient, in feet of water-level 

change per foot of horizontal distance; and

 0.0084 is the factor to convert cubic feet per day into acrefeet per year.

Equation 1 was applied to a hydrogeologic cross section 

across the mouth of Dry Valley coincident with the CaliforniaNevada State line (fig. 7). The cross section was approximately 

perpendicular to ground-water flow through the mouth of Dry 

Valley. The section extends from non-welded rhyolitic tuffs on 

the northern side of the valley floor, through unconsolidated 

sediments beneath Dry Valley Creek, and into non-welded rhyolitic tuffs on the southern side of the valley (fig. 3). The section 

is in close proximity to wells installed for this study where lithologic, borehole geophysical, and aquifer-test data are available.

Estimates of the transmissivity of unconsolidated sediments were made from 2 aquifer tests using wells near the 

mouth of Dry Valley that are completed in unconsolidated sediments (fig. 3). The first test was a multiple-well test of 24-hour 

duration from May 5 to May 6, 2003. For this test, the irrigation 

well (site 13) was pumped at an average rate of 415 gal/min., 

while water levels were recorded at a total of nine observation 

wells. The observation wells ranged from 100 to 1,700 ft from 

the pumping well and were screened at depths from 30 to 550 

ft. The second aquifer test also was a multiple-well test and conFigure 7. Hydrogeologic cross section B-B’ near the mouth of Dry Valley, west-central Nevada.
Ground-Water Discharge 17

sisted of pumping a 6-in. diameter well (site 3) installed for this 

study for a period of four hours on July 10, 2003 at an average 

rate of 43 gal/min. Water levels were recorded at an observation 

well about 1,100 ft from the pumped well, but did not respond 

to pumping during the test.

A transmissivity of 1,500 ft2/d was estimated initially with 

the more common single-well aquifer test. Single-well aquifer 

tests are more common because only one well is needed and 

analysis tend to be fairly straight forward. Drawdowns from the 

first aquifer test were analyzed using a straight-line method 

(Cooper and Jacob, 1946). Effects of partial penetration, aquifer 

heterogeneity, and water-table conditions were investigated by 

analyzing the two multiple-well aquifer tests together with a 

single numerical model. 

The analysis was accomplished using the numerical 

ground-water flow model MODFLOW (McDonald and Harbaugh, 1988; Harbaugh and McDonald, 1996) to simulate twodimensional radial flow. Hydraulic properties of 8 intervals that 

ranged from 40 to 400 ft in thickness were estimated by minimizing weighted sum-of-squares differences between simulated 

and measured drawdowns from both aquifer tests (Gill and 

others, 1981). Transmissivity of the hydrogeologic section was 

estimated by fitting simulated drawdowns to measured drawdowns from both aquifer tests. A transmissivity of 1,200 ft2

/d 

was the summation of transmissivities for each of the eight 

intervals.

Transmissivity estimates ranged from 1,200 to 1,500 ft2/d. 

The Cooper-Jacob analysis of drawdowns in the single-well test 

resulted in a transmissivity of 1,500 ft2

/d. Results of the model 

analysis of the multiple-well tests resulted in a similar transmissivity for the entire modeled section of 1,200 ft2

/d. These values 

provide reasonable estimates for the transmissivity of the 

poorly sorted unconsolidated sediments near the mouth of Dry 

Valley.

The approximate width of unconsolidated sediments 

between exposures of the non-welded tuff is about 4,000 ft 

(figs. 3 and 7). However, 0.5 mi. west of the State line the width 

of the unconsolidated sediments is about 1,500 ft, (fig. 3). To 

provide a range of estimates for subsurface flow, both widths 

were applied using equation 1. 

Based on equation 1, subsurface outflow toward Long 

Valley from Dry Valley ranges from 50 to 250 acre-ft/yr 

(table 2). Hydraulic gradients through the cross section ranged 

from 0.003 to 0.005 ft/ft (fig. 3). Transmissivity estimates 

ranged from 1,200 to 1,500 ft2/d. The width of unconsolidated 

sediments ranged from 1,500 to 4,000 ft. 

Evapotranspiration

Satellite data have been used in Nevada to estimate 

ground-water discharge by ET based on relations between 

vegetation indices derived from Landsat data and measured 

plant cover (Nichols, 2000). Nichols (2000, p. A6) determined 

that ground-water discharge by ET could be estimated as a 

function of plant cover. Plant cover, in turn, can be determined 

from Landsat data using easily calculated vegetation indices 

(Nichols, 2000, p. B6). The relation between vegetation indices 

and plant cover was used together with the relation between 

plant cover and ET rates to determine annual estimates of 

ground-water discharge by phreatophytic vegetation in Dry 

Valley. 

Ground-water discharge by ET ranges from 640 to 

790 acre-ft/yr in Dry Valley (table 3). The area of groundwater discharge by ET in Dry Valley was field mapped during 

the summer of 2002 and 2003 (fig. 8). Outside the boundary of 

the mapped area, the depth of ground water was assumed to be 

too deep for phreatophytes to grow. Within the boundary, depth 

of water is shallow and plants growing there are using ground 

water, or ground water can evaporate directly through bare soil. 

The mapped area consisted of about 620 acres of phreatophytic 

vegetation and about 1,500 acres of bare soil. Landsat data used 

to derive plant cover and compute annual ET rates were 

obtained July 8, 2003. Areas of plant cover corresponding to 

less than 10 percent, 20 to 35 percent, 35 to greater than 50 percent, and bare soil were determined from the Landsat image and 

field mapping. Estimated ET rates for mapped plant covers in 

Dry Valley ranged from 0.17 to 2.6 ft/yr, with an average rate 

for all zones about 1.5 ft/yr. Using the relations developed by 

Nichols (2000, p. B6), ET rates for each plant-cover zone were 

multiplied by the corresponding area to estimate annual groundwater discharge by ET. 

Discussion of Discharge Estimates

Estimates of natural ground-water discharge from Dry 

Valley range from a minimum of about 700 to a maximum 

of about 1,000 acre-ft/yr (table 4). The estimate of 50 to 

250 acre-ft/yr of subsurface outflow (table 2) to Long Valley, 

Calif. is smaller than the discharge estimates of 2,300 acre-ft/yr 

by Rush and Glancy (1967, p. 37) and 4,500 acre-ft/yr by Stantec Consulting Inc. and Cordilleran Hydrology (2000, p. 16). 

Although the hydraulic gradient is similar, the flow width is 

less than half and estimates of transmissivity are only about 

Table 2. Estimates of subsurface outflow from Dry Valley, westcentral Nevada

Transmissivity

(square feet 

per day)

Width

(feet)

Hydraulic gradient

(foot per foot)

Subsurface outflow,

rounded1

(acre-feet/ per year)

Minimum Maximum Minimum Maximum

1,200 4,000 0.003 0.005 120 200

1,500 4,000 0.003 0.005 150 250

1,200 1,500 0.003 0.005 50 80

1,500 1,500 0.003 0.005 60 100

1

 Calculated using equation 1, see section titled “Subsurface Outflow”.
18 Estimates of Natural Ground-Water Discharge and Characterization of Water Quality in Dry Valley, 2002–2003

12 to 20 percent of that used by the previous studies (Rush and 

Glancy, 1967, p. 37; Stantec Consulting Inc. and Cordilleran 

Hydrology, 2000, p. 16). The shorter flow width is based on 

more recent geologic mapping of the poorly permeable nonwelded rhyolitic tuffs that lie along the State line. Transmissivity values used in this study for sediments near the State line are 

based on the results of drilling, borehole-geophysical logs, and 

two aquifer tests in boreholes along the State line. 

Ground-water discharge by ET of 640 to 790 acre-ft/yr 

(table 3) is greater than the discharge of 80 acre-ft/yr by Rush 

and Glancy (1967, p. 33) and similar to the estimate of

500 acre-ft/yr by Stantec Consulting Inc. and Cordilleran 

Hydrology (2000, p. 21). The difference in estimates is due 

to a greater and more detailed mapped area of phreatophytic 

vegetation and higher ET rates being used in this report. The 

higher ET rates are based on Nichols (2000), which in turn are 

based, in part, on field-measurement studies. Areas of bare soil, 

where ground-water discharge by ET takes place from the shallow water table, was apparently not considered by either study, 

and accounts for more than one third of the estimate. 

Thomas and Albright (2003, p. 19–22) estimate average 

ground-water recharge from precipitation to range from 1,400 

to 4,800 acre-ft/yr and suggest that an overall range is 0 to 

17,000 acre-ft/yr. Their recharge estimates are based on the 

chloride mass-balance method and assumes that about 63,000 

acre-ft of precipitation falls in recharge source areas and is 

available for ground-water recharge. As part of this study, the 

maximum estimate of natural ground-water discharge from Dry 

Valley of about 1,000 acre-ft/yr is in fairly good agreement with 

the average minimum estimate of 1,400 acre-ft/yr of Thomas 

and Albright (2003, p. 22). 

Water Quality and Geochemistry

Ground-water samples were collected from 5 springs during January and March 2003 and from 3 wells screened in 

unconsolidated sediments during May and June 2003 (fig. 2; 

table 5). Field parameters (pH, dissolved oxygen, specific conductance, and water temperature) were measured on-site. Samples were collected directly from actively flowing springs and 

as close to the orifice as possible. At each well, a minimum of 

three well volumes were pumped prior to sample collection. 

Ground water was pumped through a flow-through cell and 

field parameters were monitored until they stabilized (Wilde 

and others, 1999). 

Figure 8. Area of phreatophytic vegetation and shallow depth to ground water. Satellite imagery recorded with enhanced thematic

mapper on USGS Landsat 7, Scene ID LE7043032000218950, obtained July 8, 2003, Dry Valley area, west-central Nevada.

Dry Valley Hydrographic Area Dry Valley Hydrographic Area ry Valley Hydrographic Area

Mapped area of 

phreatophytic vegetation

 and shallow depth 

to ground water

NEVADA

CALIFORNIA

NEVADA

CALIFORNIA

NEVADA

CALIFORNIA

0 2 4 MILES

0 2 4 KILOMETERS

40°00' 

39°55' 

120°00' 119°55' 119°50' 
Water Quality and Geochemistry 19

Samples for dissolved constituents were filtered in the 

field using 0.45 micron filters. Samples for cations and trace 

elements were preserved to a pH of less than 2, using concen

-

trated ultra-pure nitric acid, and samples for nutrients were 

chilled on ice. Alkalinity was measured in the field by incre

-

mental titration. Samples were analyzed for major ions, trace 

elements, nutrients, and dissolved solids at the USGS National 

Water-Quality Laboratory in Denver, Colorado. Stable isotopes 

of oxygen and hydrogen were analyzed at the USGS Stable 

Isotope Laboratory in Reston, Virginia.

Data collected by previous investigations were examined 

for a more complete characterization of water quality and 

geochemical interpretation of the ground-water system, but are 

not reproduced in this report (table 5). The Desert Research 

Institute (Thomas and Albright, 2003, p. 9–10) analyzed major 

ions and isotopes of oxygen and hydrogen in an additional 

21 samples (fig.2; DRI 1 through 21) collected from springs in 

June and July 2003. Three of the springs sampled by Thomas 

and Albright (2003) also were sampled for this study (table 5; 

sites 24, 25, and 26). Constituent concentrations and field 

parameters measured by the USGS and Thomas and Albright 

(2003) were similar for the three springs, indicating results are 

comparable. In March 2003, Bootlegger Spring (DRI 15) and 

Upper and Lower Willow Springs (DRI 16 and 17) were dry 

and Gooseberry Spring and Higgens Spring (DRI 1 and 7) were 

stagnant and were not sampled. However, Thomas and Albright 

(2003, p. 9–10) collected samples from these springs in June 

and July 2003. Spring discharge apparently resumed after heavy 

precipitation in April 2003. 

Stream samples from the lower reaches of Dry Valley 

Creek and North Fork Dry Valley Creek were sampled on April 

5, 2000 (Stantec Consulting, Inc. and Cordilleran Hydrology, 

2000, p. 19). Samples were analyzed for major ions, nitrate, dis

-

solved solids, and trace elements by the Nevada State Health 

Laboratory. Except for high pH (8.9 and 9.35), concentrations 

of all other constituents were similar to ground-water samples.

Table 3. Estimates of ground-water discharge by evapotranspiration in areas of phreatophytic vegetation, Dry Valley, west-central Nevada

General description of phreatophytic vegetation Plant cover (percent) Area (acre) Rate (feet per year) Ground-water evapotranspiration (acre-feet per year)

Area dominated by very sparse phreatophytic vegetation, primarily big sagebrush, greasewood, and rabbitbrush with occasional salt grass; water table typically ranges from about 5 to about 20 feet below land surface inwestern part of Dry Valley.

less than 10 412 0.17 70

Area dominated by sparse to moderately dense grassland, primarily salt grassand basin wildrye with occasional rabbitbrush and greasewood; water table typically ranges from a few feet to about 10 feet below land surface in western part of Dry Valley.

20 to 35 176 1.4 - 2.2 250 - 390

Area dominated by moderately to dense grassland, primarily meadowgrasses with occasional cottonwood tree and desert willow.

35 to greater than 50 33 2.5 - 2.6 80 - 90

Bare soil 1,501 0.16 240

Total 2,122 640- 790

Table 4. Estimates of natural ground-water 

discharge from Dry Valley, west-central Nevada

Discharge component

Natural ground-water

discharge

(acre-feet per year)

Minimum Maximum

Subsurface outflow 50 250

Evapotranspiration 640 790

Total (rounded) 700 1,000
Table 5. Results of chemical analyses for water samples from selected well and spring sites, Dry Valley, west-central Nevada

[Abbreviations and symbols: mg/L, milligrams per liter; μg/L, micrograms per liter; μS/cm, microsiemens per centimeter; °C, degrees Celsius; <, less than; E, estimated value; Mtified; --, not determined; Deuterium and oxygen are relative to Vienna Standard Mean Ocean Water.].

Standard

identification

Date

sampled

Specific

conductance

(μS/cm)

pH

(standard

units)

Water

temperature

(°C)

Dissolved

oxygen,

(mg/L)

Calcium

(mg/L)

Magnesium

(mg/L)

Sodium

(mg/L)

Pota

(m

Well sites

9

1419

395737119595503395734119595501395657119571601

05-14-0305-07-0306-25-03

435530528

7.47.47.5

15.512.518.5

0.2

.1

5.6

26.522.035.3

13.8

9.75

20.2

51.686.953.4

3.2.2.

Spring sites

2425262728

395846119515801395704119564501395620119590901395523119553901395516119510201

01-22-0203-11-0301-22-0201-23-0301-23-0301-23-0303-11-03

--

134

--

339260380300

--

6.3

--

6.77.67.47.2

--

12.0

--

13.0

9.59.07.2

--

6.2

--

5.6

11.5

5.26.5

--

2.76

--

3.79

23.012.350.4

--

.851

--

1.33

14.6

2.89

.581

--

21.1

--

73.015.467.014.9

--

2.

--

2.1.3.1.

Site

number

(fig. 2)

Sulfate

(mg/L)

Chloride

(mg/L)

Fluoride

(mg/L)

Bromide

(mg/L)

Silica

(mg/L)

Residue on

evaporation

(mg/L)

Nitrite plus

nitrate

(mg/L)

Nitrite(mg/L)

Ammonia

plus

organic

nitrogen

(mg/L)

Ammonia

(mg/L)

Ortho

(

Well sites

9

1419

15.829.820.0

10.414.819.6

.23.37.5

.09.12.17

62.946.155.8

303353347

.80

<.06

.94

E.004

<.008

E.005

<.10

.24

E.07

<.04

.17

<.04

Spring sites

2425262728

--

10.8

--

23.1

4.5

29.4

6.6

--

8.67

--

10.8

3.07

23.1

6.80

--

.10

--

.40

<.17

.25.07

--

.07

--

.08.04.16.04

--

58.5

--

57.047.248.731.5

--

142

--

254187268203

--

1.79

--

.83

1.31

E.04

.30

--

<.008

--

<.008<.008<.008<.008

--

<.10

--

.13

E.05

.23

<.10

--

<.04

--

E.02

<.04

.04

<.04

Site number (fig. 2) Site number (fig. 2)
Table 5. Results of chemical analyses for water samples from selected springs and well sites, Dry Valley, west-central Nevada—Continued

Site 

number

(fig. 2)

Aluminum

(μg/L)

Antimony

(μg/L)

Arsenic

(μg/L)

Barium

(μg/L)

Beryllium

(μg/L)

Boron

(μg/L)

Cadmium

(μg/L)

Chromium

(μg/L)

Cobalt

(μg/L)

Copper

(μg/L)

Iron

(μg/L)

Lead

(μg/L)

Well sites

9

1419

E1

2

M

<.30

.35

E.17

7.56.95.0

394850

<.06<.06<.06

335952

.04.04

E.03

1.1

<.8<.8

.14.47.23

.6.6

5.5

<10

19

<8

<.08<.08

.18

Spring sites

2425262728

--

9

--

E1

23

<2

--

<.30

--

<.30<.30

E.19E.20

--

1.6

--

9.41.86.32.5

--

8

--

5

141036

--

<.06

--

<.06<.06<.06<.06

--

44

--

395

146211

--

<.04

--

.07

<.04

E.02

<.04

--

<.8

--

<.8<.8<.8<.8

--

.02

--

.10.08.05.10

--

E.2

--

.4.4.4

E.2

--

<10

--

<10<10<10

E9

--

<.08

--

<.08<.08<.08

.10

311

Site

number

(fig. 2)

Manganese

(μg/L)

Molybdenum

(μg/L)

Nickel

(μg/L)

Selenium

(μg/L)

Silver(μg/L)

Strontium

(μg/L)

Thallium

(μg/L)

Vanadium

(μg/L)

Uranium

(μg/L)

Zinc

(μg/L)

Delta

deuterium

(per mil)

Well sites

9

1419

51.3

407103

8.9

13.7

5.3

.87

1.931.1

E.5

<.5

E.5

<.20<.20<.20

189208333

<.04<.04<.04

41.9

3.4

22.9

4.711.133.89

M

1

239

-113-112-105

Spring sites

2425262728

--

.5

--

18.8

.6.8

6.2

--

.7

--

24.4

.4

2.4

E.2

--

.21

--

.35

1.04

.65

2.31

--

E.3

--

E.3E.4

1.0

<.5

--

<.20

--

<.20<.20<.20<.20

--

26.2

--

27.4

164

54.0

178

--

<.04

--

<.04<.04<.04<.04

--

1.8

--

4.4

12.6

5.51.8

--

.30

--

4.071.192.995.12

--

M

--

M

<1

MM

-112-113-116-114-112-112-115

Site

number

(fig. 2)
22 Estimates of Natural Ground-Water Discharge and Characterization of Water Quality in Dry Valley, 2002–2003

Water Quality

Concentrations of selected constituents were compared 

to primary and secondary drinking-water standards (table 6). 

Primary standards are an enforceable, maximum concentration 

allowed in public water supplies; secondary standards are not 

enforceable. No primary drinking-water standards were 

exceeded for any of the constituents that were analyzed. Samples from the three wells exceeded the secondary standard for 

manganese. One spring sample (site 24) and both stream samples were outside the range for the secondary standard for pH. 

Manganese can discolor water, cause black staining, and 

leaves a bitter taste. Low pH water can leave a bitter, metallic 

taste and corrode metal pipes. High pH water can have a slippery feel, a soda taste, and cause deposits in pipes. Samples 

were not analyzed for all inorganic constituents that have a primary drinking-water standard or for organic contaminants. 

Organic contaminants were not analyzed because Dry Valley is 

undeveloped and has no known sources of pesticides, volatile 

organic compounds, or other anthropogenic contaminants.

Geochemistry of Ground Water and Streams

Dry Valley has two primary types of water chemistry that 

are distinguishable by ratios of cations, and are related to the 

lithology of the geologic units. The first primary water type is 

characterized by the sodium-bicarbonate chemistry of a spring 

near an outcrop of welded tuff of the Hartford Hill Rhyolite in 

the center of the basin (site 25, DRI 21; figs. 2 and 9). The 

second primary water type is represented by samples from Dry 

Valley Creek and several springs in the Virginia, Seven Lakes, 

and Fort Sage Mountains and has a calcium-magnesium-bicarbonate chemistry (fig. 9). Much of these mountains are comprised of basaltic rocks of the Pyramid Sequence which overlie 

the Hartford Hill Rhyolite. The higher ratio of calcium and 

magnesium to sodium observed in the second primary water 

type likely is due to the mafic to intermediate chemistry associated with the Pyramid Sequence. The different chemistry represented by site 25 indicates a different source area of recharge 

than that of the second primary water type. Ground water discharging at the spring (site 25) has probably moved through the 

Hartford Hill Rhyolite exposed up gradient over the entire 

northern end of Dogskin Mountain. The absence of the Pyramid 

Sequence along this flow path would explain this unique chemistry observed in the center of the basin.

The Hartford Hill Rhyolite has about two times more 

sodium than calcium or magnesium (Bonham, 1969, p. 24). The 

sodium-bicarbonate chemistry of site 25 likely is due to dissolution of albite, a sodium feldspar that is a common silicate mineral in rhyolite (Hurlbert and Klein, 1977, p. 430). Hydrolysis 

of silicate minerals occurs by a sequence of reactions that begin 

when carbon dioxide in the atmosphere forms carbonic acid in 

water (eq. 2). Carbonic acid dissociates to yield hydrogen and 

bicarbonate ions (eq. 3). Hydrogen ions then react with albite, 

forming kaolinite and releasing silica and sodium ions (eq. 4; 

Hem, 1985, p. 62): 

CO2(g) + H2O = H2CO3(aq) (2)

2H2CO3(aq) = 2H++2HCO3

- (3)

2NaAlSi3O8(c) + 2H+ + 9H2O(1) = Al2Si2O5(OH)4(c) + 

4H4SiO4(aq) + 2Na+ (4)

Table 6. Comparison of selected inorganic constituents for primary 

and secondary drinking-water standards, in Dry Valley, west-central Nevada

[Abbreviations and symbols: mg/L, milligrams per liter; μg/L, micrograms per 

liter; <, less than; TT, a required process intended to reduce the level of a contaminant in drinking water.]

Contaminant

Maximum 

allowed

concentration

Maximum measured

concentration

(see table 5)

Primary drinking water standards

Antimony (μg/L)

Arsenic (μg/L)

Barium (μg/L)

Beryllium (μg/L)

Cadmium (μg/L)

6 a

10

a

Effective date January 23, 2006

2000

4

5

<.35

9.4

0.050

<0.06

0.07

Chromium (total, μg/L)

Copper (μg/L)

Fluoride (mg/L)

Lead (μg/L)

Nitrate (mg/L)

100

1,300. (TT)

4

15. (TT)

10

1.1

5.5

0.40

0.10

1.79

Nitrite (mg/L)

Selenium (μg/L)

Thallium (μg/L)

Uranium (μg/L)

1

50

2

30

<0.008

1.0

<0.04

5.12

Secondary drinking water standards

Aluminum (μg/L)

Chloride (mg/L)

Copper (μg/L)

Fluoride (mg/L)

Iron (μg/L)

50 to 200

250

1,000

2

300

9

23.1

5.5

0.40

19

Manganese (μg/L)

pH (standard units)

Silver (μg/L)

Sulfate (mg/L)

Zinc (μg/L)

Dissolved solids (mg/L)

50

6.5– 8.5

100

250

5,000

500

407

6.3 - 7.5

<0.2

29.8

239

353
Water Quality and Geochemistry 23

PERCENT

CALCIUM

100 

80

60

40

20

0

 0 

 20 

 40 

 60 

 80 

 100 

MAGNESIUM

0 

20 

40 

60 

80 

100 

SODIUM PLUS POTASSIUM

CHLORIDE, FLUORIDE, NITRITE PLUS NITRATE

 0 

 20 

 40 

 60 

 80 

 100 

 100 

 80 

 60 

 40 

 20 

 0 

CARBONATE PLUS BICARBONATE

 100 

 80 

 60 

 40 

 20 

 0 

SULFATE

 0 

 20 

 40 

 60 

 80 

 100 

SULFATE PLUS CHLORIDE

 0 

 20 

 40 

 60 

 80 

 100 

CALCIUM PLUS MAGNESIUM

 100 

 80 

 60 

 40 

 20 

 0 

 100 

 80 

 60 

 40 

 20 

 0 

PERCENT

PERCENT

Secondary water type

(sites 24, 27, DRI 1, 8, 9)

Secondary water type

(sites DRI 15,16,17)

First primary water type

(sites 25, DRI 21)

site

14

Streamflow

site 9

site

19

Second primary water type

(sites 26, 28, DRI 2-6, 

DRI 10-14, DRI 18-20)

Figure 9. Ratios of major ion chemistry for water sampled in Dry Valley, west-central Nevada.
24 Estimates of Natural Ground-Water Discharge and Characterization of Water Quality in Dry Valley, 2002–2003

The sodium and bicarbonate produced by these reactions 

explain the chemistry of site 25. A similar reaction occurs during hydrolysis of other silicate minerals. Alternatively, rocks 

with a mafic to intermediate composition, similar to the Pyramid Sequence, would produce large amounts of calcium, magnesium, and bicarbonate. 

Evaporation appears to have altered the two primary types 

of water chemistry at certain springs. Springs sampled in the 

southern Fort Sage Mountains have a calcium-magnesiumsulfate chemistry, which is not typical of springs that discharge 

from the Pyramid Sequence (fig. 9; DRI 15, 16, and 17). 

Springs sampled in the eastern Seven Lakes Mountain (site 27 

and DRI 1) and in the northern Dogskin Mountains (site 24 and 

DRI 8, and 9) have a sodium-bicarbonate-sulfate chemistry, 

which is not typical of springs that discharge from the Hartford 

Hill Rhyolite. Most of these springs were dry or stagnant in 

March 2003, but flow resumed in April and were sampled in 

June 2003 by Thomas and Albright (2003). Evaporation of 

spring discharge would concentrate dissolved ions and, if discharge completely stopped, precipitate carbonate, sulfate, and 

chloride salts. When discharge resumes, the spring chemistry 

would change due to preferential dissolution of chloride first, 

then sulfate, and finally carbonate salts (Drever, 1988, p. 240). 

As salts are flushed out, concentrations and ratios of ions would 

approach the primary water chemistry. This would explain the 

high ratios of sulfate to bicarbonate in these samples as compared to the primary water types. 

Ion ratios in ground water of the basin-fill aquifer (sites 9, 

14, and 19) and in streamflow (Stantec Consulting, Inc. and 

Cordilleran Hydrology, 2000, p. 19) plot between the two primary water types, indicating a mixture of water (fig. 9). Springs 

with secondary chemistry have little to no affect on the chemistry of ground water in the basin-fill aquifer and streamflow. Ion 

ratios in shallow ground water near Dry Valley Creek in the 

center of the basin (site 19), deep ground water near the State 

line (site 9), and streamflow are similar to springs that discharge 

from the Pyramid Sequence. Ion ratios in shallow ground water 

near the mouth of Dry Valley (site 14) appear to be about an 

equal mixture of the two primary water types, indicating mixing 

of ground water that has moved through both the Pyramid 

Sequence and Hartford Hill Rhyolite. Additional ground water 

could be discharging along a fault or fault zone at shallow 

depths into the unconsolidated sediment, resulting in the mixed 

chemistry observed in the shallow ground water near the State 

line.

Chloride is a good indicator of evaporation because it 

behaves conservatively relative to other major ions. If evaporation is the main process affecting constituent concentrations, 

then there should be a positive, linear relation between chloride 

and dissolved-solids concentrations. This assumes that recharge 

is the only source of chloride and minerals do not precipitate 

along ground-water flow paths. Precipitation and dry fallout 

likely is the only source of chloride in Dry Valley because mafic 

rocks and rhyolite are not significant sources. If chloride salts 

were present in the unconsolidated sediments, then concentrations and ratios of chloride to other anions should be higher in 

ground water than in spring discharge. 

Calcite is commonly the first salt to reach saturation and 

subsequently precipitate from solution. To determine if calcite 

could precipitate from ground water in Dry Valley, saturation 

indices (SIcalcite) were calculated using WATEQ4F (Ball and 

Nordstrom, 1991). If calcite has not reached saturation, it is 

unlikely that other salts have reached saturation. SIcalcite values 

of zero (±0.3) indicate that the water is at or near equilibrium 

and that calcite could precipitate. SIcalcite values indicate only 

three springs (DRI 5, 15, and 17; Thomas and Albright, 2003) 

and one ground-water sample (site 19) are at equilibrium with 

respect to calcite and the remaining samples are under saturated 

(table 7). Therefore, it is unlikely that significant amounts of 

salts are precipitating along ground-water flow paths. However, 

minerals likely will precipitate around spring orifices as discharge evaporates. 

The relation between chloride and dissolved-solids concentrations for samples collected in Dry Valley generally is positive and linear, but exhibit different slopes for primary and secondary water chemistries (fig. 10). Springs with primary water 

chemistry, ground water in unconsolidated sediments, and 

streamflow all plot along the same trend. Sites 9, 14, 19, 25, and 

27 have the highest chloride and dissolved solids concentrations 

(table 5). This relation and the ratios of major ions (fig. 9) indicate that ground water has evolved by evaporation of primary 

waters and mixing with water that is characterized by the chemistry observed at site 25. The mean and median chloride concentration for springs with a primary water chemistry is 4.5 and 4.8 

mg/L, respectively. Chloride concentrations in streamflow were 

7 and 9 mg/L. Chloride concentrations in deep ground water 

(site 9) and in the spring on the valley floor (site 25) were 10.4 

and 10.8 mg/L, respectively. Concentrations of chloride in shallow ground water (sites 14 and 19) are 14.8 and 19.6 mg/L. If 

spring discharge represents recharge to the deeper ground water 

and streamflow infiltration recharges the shallow ground water, 

then about 50 percent of spring discharge and streamflow would 

need to evaporate to obtain the chloride concentrations that 

were measured in ground water.

Compared to the relation for primary water chemistries, 

springs that were stagnant have high chloride concentrations 

and springs that had ceased to flow have low concentrations for 

the same dissolved-solids concentrations. These differences 

could be due to the nature of spring discharge and flushing of 

salts that had accumulated around the spring orifice. Soils 

around springs that are stagnant are moist, indicating that evaporation is continually accumulating salts in the discharge zone 

even when there is no visible flow. Carbonate salts could precipitate in the diffuse discharge zone without precipitation of 

chloride salts, which could explain the high chloride to dissolved- solids ratio for these springs. Soils were dry around 

springs that ceased to flow, so all salts would have precipitated 

in the discharge zone. When spring discharge resumes, preferential dissolution of chloride salts could result in initially high 

chloride to dissolved-solids ratio for these springs. Continued 
Water Quality and Geochemistry 25

discharge would flush the chloride salts from the discharge zone 

resulting in low chloride to dissolved-solids ratios for springs 

that had been previously dry. 

Stable isotopes of oxygen and hydrogen of water are useful 

in determining if different sources of water are hydraulically 

connected and if water has evaporated. The stable isotopes evaluated were oxygen-18 relative to oxygen-16 (18O/16O) and deuterium (hydrogen-2) relative to hydrogen-1 (2H/1H). Each ratio 

is determined for a sampled water and then related mathematically to the comparable ratio for an international reference 

standard known as Vienna-Standard Mean Ocean Water 

(V-SMOW; Fritz and Fontes, 1980). By convention, the computed results are expressed as delta oxygen-18 (δ18O) and delta 

deuterium (δD) in parts per thousand (abbreviated “permil” or 

‰). The delta notation is computed from the equation:

δ = [(Rx - Rstd)/Rstd] *1,000 (5)

where δ is the delta notation of δ18O or δD;

Rx is the ratio of 18O/16O or 2H/1H measured in sample;

Rstd is the ratio of 18O/16O or 2H/1H in standard.

Water that is enriched in lighter isotopes (1H and 16O) relative to V-SMOW has negative values. Evaporation and condensation are the most significant processes that change delta 

values. Variations in 18O/16O and 2H/1H in ground water reflect 

differences in latitude, altitude, and seasonal variations, which 

are factors that affect recharge temperature. The ratios of these 

isotopes are virtually unaffected by low-temperature geochemical processes in ground water (Muir and Coplen, 1981), such 

as in Dry Valley. 

Springs and ground water are part of the same flow system 

in Dry Valley indicated by linear related δD and δ18O values 

(fig. 11). In general, high altitude springs have the most negative values and ground water from the unconsolidated sediments has the least negative values. The slope of δD‰ versus 

δ18O‰ in ground water and springs in Dry Valley is 4.2 compared to a slope of 8 for global meteoric water (Craig, 1961; 

fig.11). In contrast, δD‰ versus δ18O‰ in ground water from 

Spanish Springs Valley plots nearly parallel to the global meteoric water line (Berger and others, 1997, p. 34; Seiler, 1999). 

A slope between 3 and 6 is characteristic of evaporation from 

surface water (Coplen and others, 2000, p. 87), indicating 

springs and ground water in Dry Valley are similar to surfacewater than a typical ground-water system. 

Isotopes and concentrations of major ions and their ratios 

indicate that a large volume of water is evaporated along 

ground-water flow paths in Dry Valley. Evapotranspiration of 

ground water by phreatophytic vegetation was estimated to be 

about 640 to 790 acre-ft/yr, which is a small fraction of the total 

precipitation that falls in Dry Valley and could not explain the 

chemistry indicating evaporation throughout the basin. Most of 

the springs in Dry Valley discharge from bedrock areas in the 

surrounding mountain blocks. The amount of subsurface discharge directly from bedrock areas to the basin-fill aquifer is 

unknown, but the chloride concentration and isotopes from 

deep ground water suggest it is small. It is possible that much of 

the spring discharge evaporates before it recharges the basin-fill 

aquifer. If evaporation of spring discharge is significant before 

it recharges the basin-fill aquifer, then using chemistry data 

from springs would overestimate ground-water recharge.

Table 7. Saturation indices of calcite

(SIcalcite) for ground water in Dry Valley,

west-central Nevada

Site number

(fig. 2) SIcalcite

a

Saturation index = log [Activity product]/KTwhere KT = equilibrium constant at temperature T.

By convention, a positive value indicates a mineral 

can precipitate from solution, and a negative value 

indicates a mineral can dissolve if present.

a

Well sites (fig. 2)

9

14

19

-0.4

-0.6

-0.1

Spring sites (fig. 2)

24

25

26

27

28

-3.2

-2.1

-0.4

-1.0

-0.5

Spring Sites

(Thomas and Albright, 2003, table 4)

DRI-1

DRI-2

DRI-3

DRI-4

DRI-5

-2.4

-0.8

-0.4

-0.6

0.2

DRI-6

DRI-7

DRI-8

DRI-9

DRI-10

-2.8

-0.4

-2.2

-3.2

-1.3

DRI-11

DRI-12

DRI-13

DRI-14

DRI-15

-2.4

-1.3

-1.6

-1.4

-0.2

DRI-16

DRI-17

DRI-18

DRI-19

DRI-20

DRI-21

-0.9

-0.2

-1.6

-2.1

-2.2

-2.1
26 Estimates of Natural Ground-Water Discharge and Characterization of Water Quality in Dry Valley, 2002–2003

0 200 400 600 800 1000

DISSOLVED SOLIDS, IN MILLIGRAMS PER LITER

0

10

20

30

40

50

CHLORIDE, IN MILLIGRAMS PER LITER

Primary water type

Secondary water type

-17 -16 -15 -14 -13

-135

-130

-125

-120

-115

-110

-105

-100

-95

Meteoric water line (Craig, 1961)

DELTA OXYGEN-18, IN PERMIL

DELTA DEUTERIUM, IN PERMIL

Spanish Springs Valley (Berger and others, 1997; Seiler, 1999)

Samples from Spanish Springs Valley 

 (Berger and others, 1997; Seiler, 1999) 

Dry Valley

Samples from Dry Valley

Figure 10. Chloride as a function of dissolved-solids concentration, Dry Valley, west-central Nevada.

Figure 11. Relation of deuterium to oxygen-18 in sampled ground water and springs in Dry Valley, west-central Nevada.
Summary 27

Summary

The Dry Valley Hydrographic Area is being considered as 

a source area for additional water supplies for the Reno-Sparks 

area, which is about 25 mi to the south of Dry Valley. Current 

estimates of annual ground-water recharge to Dry Valley have 

a considerable range and are a direct function of the particular 

precipitation data used in the recharge estimate. Because estimating ground-water discharge has more certainty than estimating ground-water recharge from precipitation, the USGS, in 

cooperation with Washoe County, began a three-year study to 

re-evaluate the ground-water resources in Dry Valley, with 

emphasis on estimating natural ground-water discharge. 

The boundary of the Dry Valley Hydrographic Area 

encompasses about 82 mi2 in Washoe County, Nev. and about 

3 mi2

 in Lassen County, Calif. Dry Valley is topographically 

open to the west and is bounded on the north, east, south by 

fault-controlled mountain blocks. The Nevada-California State 

line was chosen as the western boundary of the study area to 

provide a practical location for estimating ground-water outflow. Dry Valley Creek, which drains the entire area of Dry 

Valley, flows across the western boundary and is tributary to 

Long Valley Creek in California.

Phreatophytic vegetation on the valley floor consists of 

saltgrass with small isolated stands of greasewood, rabbitbrush, 

and big sagebrush. Based on field mapping and satellite imagery acquired on July 8, 2002, phreatophytic vegetation covers 

about 620 acres. Areas of bare soil, where ground-water ET 

takes place from the shallow water table, covers about 1,500 

acres. Riparian type vegetation found along stream channels 

and near springs and ground-water seeps includes cottonwood 

trees, willows, and a variety of shrubs and grasses.

Dry Valley is near the intersection of the northwest-trending strike-slip Walker Lane fault zone and the north-trending 

normal-type Sierra Nevada frontal fault zone. Northwest trending strike-slip faults are mapped near the mouth of Dry Valley 

on the western side and along a zone through the center of Dry 

Valley. Movement along these faults also is vertical, producing 

the uplift of Dogskin Mountain. In unconsolidated sediments, 

faults usually are barriers to ground-water, whereas the effect of 

faulting on ground-water flow in consolidated rocks is variable 

and difficult to predict without water-level data near the fault.

The mountain blocks surrounding Dry Valley are composed of granitic rocks of pre-Cenozoic age, overlain by two 

volcanic rock units of Tertiary age. Granitic rocks make up the 

bulk of the Sierra Nevada west of Dry Valley. Near Dry Valley 

they are exposed near the center of Fort Sage Mountain, on the 

southern part of Dogskin Mountain, and on the western flank of 

Seven Lakes Mountain. The granitic rocks likely are thousands 

of feet thick and form a relatively impermeable basement to 

ground-water flow.

The oldest volcanic rocks overlying the granitic rocks are 

welded to non-welded rhyolitic tuffs of early to middle Miocene 

age, mapped as the Hartford Hill Rhyolite. The maximum thickness of the tuffs is about 4,000 ft and they may extend into the 

subsurface beneath Long Valley and western Dry Valley. Near 

the mouth of Dry Valley, the tuffs appear to be largely nonwelded and may include tuffaceous-sedimentary deposits. 

Where welded, the tuffs may be capable of transmitting ground 

water. Where non-welded, the tuffs and tuffaceous-sedimentary 

deposits are likely relatively impermeable.

Overlying the rhyolitic tuffs is a complex mixture of 

basalt, basaltic andesite, andesite flows, and flow breccias, 

interbedded with sedimentary rocks of diatomite and shale, 

rhyolitic tuffs and tuff breccias, and dacite welded tuffs. These 

rocks are informally assigned to the Pyramid Sequence of late 

Miocene age. They cover large areas of the Virginia Mountains 

and are exposed on the southern and northern flanks of the Fort 

Sage and Seven Lakes Mountains, respectively. The thickness 

of the unit may range from 2,000 to 3,000 ft. 

Unconsolidated sediments beneath and along the margins 

of the floor of Dry Valley HA consist of stream and alluvial 

fan deposits of Quaternary age and deposits derived from 

Pleistocene Lake Lahontan. High stands of Lake Lahontan 

extended about 2.7 mi east of the State line into the mouth of 

Dry Valley. As the levels of Lake Lahontan rose and fell, 

deposition near the western side of Dry Valley alternated 

between fine-grained silts and clay during high stands, and 

coarse-grained beach and stream deposits during low stands, 

producing poorly sorted sediments.

Geophysical logs collected from boreholes of wells 

installed near the State line show sand and gravel layers alternating with clay throughout the upper 200 to 250 ft of the 

boreholes. Below that depth, sediments become progressively 

more clayey with a sand and gravel layer about 20 ft thick near 

400 ft, and relatively thin stringers of sand near 490 and 510 ft. 

Below that depth, sediments are mostly clay. Seismic-refraction 

data show velocities typical of unsaturated and saturated unconsolidated sediments 2,500 to 6,600 ft/s to a depth of about 200 ft 

below land surface. Beneath 200 ft, velocities are about 

8,000 ft/s, more typical of saturated semi-consolidated sediments. The aquifer materials likely are poorly permeable at 

depths more than 200–250 ft beneath the floor of Dry Valley.

Streamflow observations and miscellaneous discharge 

measurements collected from Dry Valley Creek, about one mile 

west of the State line, indicate a maximum of about 210 acre-ft 

of surface water outflow from Dry Valley in the 2003 water 

year. Precipitation in the region during the 2003 water year was 

about 78 percent of the long-term average, which may account 

for the low streamflow from Dry Valley. Rush and Glancy 

(1967, p. 30), suggest that the long-term average annual streamflow exiting Dry Valley at the State line is 4,000 acre-ft/yr. 

Water levels in wells on the floor of Dry Valley confirm 

that ground-water flow is toward the west. The water-table gradient near the State line changes from 0.003 ft/ft east of the 

State line to 0.005 ft/ft west of the State line. The change in 

gradient across the State line may be caused by the combination 

of less permeable lake deposits to the west and restriction of 

ground-water flow through the narrow width of unconsolidated 

sediments west of the State line. The non-welded rhyolitic tuffs 
28 Estimates of Natural Ground-Water Discharge and Characterization of Water Quality in Dry Valley, 2002–2003

on the northern and southern sides of the unconsolidated sediments are poorly permeable and produce a damming effect on 

ground-water upgradient from the State line.

Ground-water flow from the upper part of Dry Valley to 

Winnemucca Valley likely is not significant based on similar 

altitudes for phreatophytes in each valley. Ground-water outflow from the upper part of Dry Valley to Honey Lake near the 

California-Nevada State line is not likely because of a lack of 

springs in that part of Honey Lake Valley.

Analysis of two aquifer tests show the transmissivity of 

poorly sorted sediments near the western side of Dry Valley is 

1,200 to 1,500 ft2

/day. The width of unconsolidated sediments 

ranges from 1,500 to 4,000 ft near the State line. The hydraulic 

gradient east and west of the State line ranges from 0.003 to 

0.005. Using these values with Darcy’s Law, estimates

of subsurface outflow to Long Valley ranges from 50 to 

250 acre-ft/yr. 

About 640 to 790 acre-ft/yr of ground water is lost to 

evapotranspiration in Dry Valley. Combining subsurface-outflow estimates with ground-water evapotranspiration estimates, 

total natural ground-water discharge from Dry Valley ranges 

from a minimum of 700 acre-ft to a maximum of 1,000 acre-ft 

annually. 

Water quality in Dry Valley generally is good and primary 

drinking-water standards were not exceeded in any samples collected. The secondary standard for manganese was exceeded in 

three ground-water samples. One spring sample and two surface-water samples were outside the range for the secondary 

standard for pH. Dry Valley has two primary types of water 

chemistry that are distinguishable by cation ratios and related 

to the two volcanic units that make up much of the surrounding 

mountains. In addition, two secondary types of water chemistry 

appear to have evolved by evaporation of the primary water 

types. Ground water near the State line appears to be almost an 

equal mixture of the two primary water chemistries and has as 

an isotopic characteristic similar to evaporated surface water.

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Appendix—Selected ground-water levels measured in wells, Dry Valley, west-central Nevada 31

Appendix—Selected ground-water levels measured in wells,

Dry Valley, west-central Nevada
32 Estimates of Natural Ground-Water Discharge and Characterization of Water Quality in Dry Valley, 2002–2003

Appendix—Selected ground-water levels measured in wells, Dry Valley, west-central Nevada

Site number is a short identification number in this report. 

Each U.S. Geological Survey data-collection site is assigned a unique identification on the basis of geographic location. Wells and 

springs are identified by a local system (Nevada and California) and a standard latitude-longitude system. For convenience, short site 

number (1 - 28) also are used for sites discussed in this report. In California wells are numbered according to their location in the rectangular system for subdivision of public lands. Identification consists of the township number, north or south (N or S); the range number, 

east or west (E or W); and the section number. Each section is divided into sixteen 40-acre tracts lettered consecutively (except I and O) 

beginning with “A” in the northeast corner of the section and progressing in a sinusoidal manner to “R” in the southeast corner. Within 

the 40-acre tract, wells are sequentially numbered in the order they are inventoried. The final letter (M) refers to the Mount Diablo base 

line and meridian. In Nevada, a local site designation is used to identify a site by hydrographic area (Rush, 1968) and by the official rectangular subdivision of the public lands referenced to the Mount Diablo base line and meridian. Each site designation consists of four 

units. The first unit is the hydrographic area number. The second unit is the township, preceded by N to indicate location north of the base 

line. The third unit is the range, preceded by “E” to indicate location east of the meridian. The fourth unit consists of the section number 

and letters designating the quarter section, quarter-quarter section and so on (A, B, C, and D indicate the northeast, northwest, southwest, 

and southeast quarter, respectively), followed by a number indicating the sequence in which the site was recorded.

The standard identification is based on the grid system of latitude and longitude. The number consists of 15 digits. The first six digits denote the degrees, minutes, and seconds of latitude; the next seven digits denote the degrees, minutes, and seconds of longitude; and the 

last two digits (assigned sequentially) identify the sites within a 1-second grid. The assigned number is retained as a permanent identifier 

even if a more precise latitude and longitude are later determined.

Measurement method: S, steel tape; T, electric tape.

Site

number 

(fig. 2)

Local identification Standard identification Water-level

date

Water level

below

land surface

Measurement

method

1 024N018E06H01M 395832119595901 02/06/2002

08/21/2002

01/07/2003

03/06/2003

05/05/2003

116.57

116.51

116.55

116.55

117.89

T

T

T

T

S

06/19/2003

08/14/2003

11/20/2003

01/30/2004

118.07

116.55

113.40

114.23

S

T

T

T

2 024N018E07D01M 395748120004601 02/12/2002

08/21/2002

01/07/2003

03/06/2003

05/05/2003

6.94

7.41

6.77

6.89

6.86

T

T

T

T

S

06/19/2003

08/14/2003

11/20/2003

01/30/2004

7.12

7.61

7.28

7.12

S

T

T

T

3 095 N24 E18 07ADAB1 395747119595401 11/13/2002

11/19/2002

12/19/2002

12/23/2002

12/30/2002

9.00

6.11

3.23

3.20

3.12

R

T

T

T

T

01/07/2003

01/21/2003

01/22/2003

01/22/2003

01/23/2003

2.95

2.80

2.80

2.81

2.81

T

T

T

T

T
Appendix—Selected ground-water levels measured in wells, Dry Valley, west-central Nevada 33

Appendix—Selected ground-water levels measured in wells, Dry Valley, west-central Nevada--Continued

Site

number 

(fig. 2)

Local identification Standard identification Water-level 

date

Water level

below

land surface

Measurement

method

02/12/2003

03/06/2003

03/28/2003

05/01/2003

05/01/2003

2.65

2.56

2.52

2.50

2.51

T

T

T

T

T

05/14/2003

06/19/2003

07/01/2003

07/08/2003

08/14/2003

2.63

2.95

3.08

3.20

3.74

T

S

T

T

T

11/20/2003

01/30/2004

3.91

3.57

T

T

4 095 N24 E18 09BCBD1 395743119582401 10/05/1980

08/21/2002

11/19/2002

01/22/2003

03/06/2003

30.

37.81

37.71

37.77

37.75

R

S

T

T

T

05/05/2003

06/19/2003

08/14/2003

11/20/2003

01/30/2004

37.49

37.28

37.47

37.63

37.79

S

S

T

T

T

5 024N017E01F01M 395740120012601 03/06/2003

03/28/2003

05/05/2003

06/19/2003

08/14/2003

16.02

15.94

16.01

15.90

16.43

S

S

S

S

S

11/20/2003

01/30/2004

16.84

16.78

S

S

6 095 N24 E18 08ACCC1 395739119591401 10/21/2002

11/19/2002

01/07/2003

01/21/2003

01/22/2003

7.85

7.39

6.39

6.12

6.11

T

T

T

T

T

02/12/2003

03/06/2003

03/28/2003

05/05/2003

05/07/2003

5.92

5.75

5.70

5.65

5.65

T

T

T

S

T

05/14/2003

06/19/2003

08/14/2003

11/20/2003

01/30/2004

5.65

6.52

7.94

7.94

7.40

T

S

T

T

T

7 024N018E07G001M 395737120001301 11/20/2003

01/30/2004

9.76

9.55

S

S
34 Estimates of Natural Ground-Water Discharge and Characterization of Water Quality in Dry Valley, 2002–2003

8 095 N24 E18 17DAAB2 395737119595502 11/10/2002

11/14/2002

11/19/2002

12/19/2002

12/23/2002

9.00

7.62

7.45

6.48

6.35

R

T

T

T

T

12/30/2002

01/07/2003

01/21/2003

01/22/2003

01/23/2003

6.28

6.08

5.76

5.77

6.53

T

T

T

T

T

02/12/2003

03/06/2003

03/28/2003

05/01/2003

05/01/2003

5.50

4.95

4.50

5.05

5.03

T

T

T

T

T

05/01/2003

05/01/2003

05/01/2003

05/01/2003

05/14/2003

5.04

5.04

5.04

5.24

6.97

T

T

T

T

T

06/19/2003

07/01/2003

07/08/2003

07/10/2003

07/10/2003

7.10

7.24

7.07

7.91

7.90

S

T

T

T

T

07/10/2003

07/10/2003

07/16/2003

08/14/2003

11/20/2003

01/30/2004

7.92

7.95

11.00

9.71

7.38

7.01

T

T

T

T

T

T

9 095 N24 E18 07DAAB1 395737119595501 11/10/2002

11/14/2002

11/19/2002

12/19/2002

12/23/2002

9.00

10.37

10.59

10.20

10.12

R

T

T

T

T

12/30/2002

01/07/2003

01/21/2003

01/22/2003

01/23/2003

10.10

9.88

9.79

9.81

10.70

T

T

T

T

T

02/12/2003

03/06/2003

03/28/2003

05/01/2003

05/01/2003

9.71

9.76

8.80

15.52

10.25

T

T

T

T

T

Appendix—Selected ground-water levels measured in wells, Dry Valley, west-central Nevada--Continued

Site

number 

(fig. 2)

Local identification Standard identification Water-level 

date

Water level

below

land surface

Measurement

method
Appendix—Selected ground-water levels measured in wells, Dry Valley, west-central Nevada 35

05/01/2003

05/01/2003

05/01/2003

05/14/2003

06/19/2003

10.78

12.59

14.03

10.14

11.25

T

T

T

T

S

07/01/2003

07/08/2003

07/10/2003

07/10/2003

07/10/2003

10.43

10.90

12.44

12.26

12.19

T

T

T

T

T

07/10/2003

07/16/2003

08/14/2003

11/20/2003

01/30/2004

12.57

8.19

11.67

10.69

10.39

T

T

T

T

T

10 095 N24 E18 08CBAA1 395736119593501 09/18/2002

09/23/2002

11/19/2002

12/30/2002

01/07/2003

4.00

3.74

3.38

2.66

2.43

R

T

T

T

T

03/06/2003

05/01/2003

08/14/2003

11/20/2003

01/30/2004

2.28

.98

3.39

3.82

3.28

T

T

T

T

T

11 095 N24 E18 08CBAA2 395735119593401 09/18/2002

09/23/2002

11/19/2002

12/19/2002

12/30/2002

4.00

3.61

3.20

2.70

2.33

R

T

T

T

T

01/07/2003

01/21/2003

01/22/2003

02/12/2003

03/06/2003

2.16

1.97

1.99

1.79

1.53

T

T

T

T

T

03/28/2003

05/01/2003

05/07/2003

08/14/2003

11/20/2003

01/30/2004

1.65

1.85

1.93

3.53

3.55

3.11

T

T

T

T

T

T

12 095 N24 E18 09CABB1 395735119582401 11/19/2002

01/22/2003

03/06/2003

05/05/2003

06/19/2003

24.36

24.46

24.32

24.45

24.82

T

T

T

S

S

Appendix—Selected ground-water levels measured in wells, Dry Valley, west-central Nevada--Continued

Site

number 

(fig. 2)

Local identification Standard identification Water-level 

date

Water level

below

land surface

Measurement

method
36 Estimates of Natural Ground-Water Discharge and Characterization of Water Quality in Dry Valley, 2002–2003

08/14/2003

11/20/2003

01/30/2004

24.46

24.98

25.21

T

T

T

13 024N018E07J01M 395734119595601 12/27/1990

02/06/2002

08/21/2002

11/19/2002

12/19/2002

6.00

10.37

11.45

11.40

11.05

R

T

T

T

T

12/23/2002

12/30/2002

01/07/2003

01/21/2003

01/23/2003

10.98

10.91

10.75

10.65

11.24

T

T

T

T

T

03/06/2003

03/28/2003

05/01/2003

05/01/2003

05/01/2003

10.48

10.55

84.50

90.95

89.60

T

T

T

T

T

05/01/2003

05/01/2003

05/01/2003

05/01/2003

05/14/2003

86.80

81.50

63.50

10.96

10.69

T

T

T

T

T

06/19/2003

07/08/2003

07/10/2003

08/14/2003

11/20/2003

01/30/2004

12.35

12.19

13.45

12.92

11.70

11.56

S

T

T

T

S

T

14 095 N24 E18 07DAAC3 395734119595503 11/05/2002

11/09/2002

11/11/2002

11/12/2002

11/14/2002

8.00

5.3

5.7

8.66

6.94

R

T

T

T

T

11/19/2002

12/19/2002

12/23/2002

12/30/2002

01/07/2003

6.94

6.12

6.02

5.90

5.83

T

T

T

T

T

01/21/2003

01/22/2003

01/23/2003

02/12/2003

03/06/2003

5.74

5.72

6.05

5.64

5.60

T

T

T

T

T

Appendix—Selected ground-water levels measured in wells, Dry Valley, west-central Nevada--Continued

Site

number 

(fig. 2)

Local identification Standard identification Water-level 

date

Water level

below

land surface

Measurement

method
Appendix—Selected ground-water levels measured in wells, Dry Valley, west-central Nevada 37

03/28/2003

05/01/2003

05/01/2003

05/01/2003

05/01/2003

5.55

5.88

5.78

5.58

5.96

T

T

T

T

T

05/01/2003

05/01/2003

05/01/2003

05/14/2003

06/19/2003

5.68

5.58

5.75

6.05

6.79

T

T

T

T

S

07/08/2003

07/10/2003

08/14/2003

11/20/2003

01/30/2004

6.83

7.43

7.46

7.15

6.75

T

T

T

T

T

15 095 N24 E18 07DAAC2 395734119595502 11/05/2002

11/09/2002

11/11/2002

11/12/2002

11/14/2002

13.00

11.90

12.20

15.20

11.91

R

T

T

T

T

11/19/2002

12/19/2002

12/23/2002

12/30/2002

01/07/2003

12.46

8.45

8.44

8.43

8.18

T

T

T

T

T

01/22/2003

01/23/2003

02/12/2003

03/06/2003

03/28/2003

7.75

8.66

7.51

7.51

7.53

T

T

T

T

T

05/01/2003

05/01/2003

05/01/2003

05/01/2003

05/01/2003

12.58

11.16

8.26

8.53

8.21

T

T

T

T

T

05/01/2003

05/01/2003

05/14/2003

06/19/2003

07/08/2003

9.83

8.21

9.32

13.87

12.71

T

T

T

S

T

07/10/2003

08/14/2003

11/20/2003

01/30/2004

15.44

14.59

11.92

11.57

T

T

T

T

Appendix—Selected ground-water levels measured in wells, Dry Valley, west-central Nevada--Continued

Site

number 

(fig. 2)

Local identification Standard identification Water-level 

date

Water level

below

land surface

Measurement

method
38 Estimates of Natural Ground-Water Discharge and Characterization of Water Quality in Dry Valley, 2002–2003

16 095 N24 E18 07DAAC1 395734119595501 11/05/2002

11/09/2002

11/11/2002

11/12/2002

11/14/2002

16.00

33.40

38.70

17.49

15.40

R

T

T

T

T

11/19/2002

12/03/2002

12/19/2002

12/23/2002

12/30/2002

15.06

20.76

19.43

19.37

19.26

T

T

T

T

T

01/07/2003

01/21/2003

01/22/2003

01/23/2003

02/12/2003

19.07

16.39

17.39

17.30

17.24

T

T

T

T

T

03/06/2003

03/28/2003

05/01/2003

05/01/2003

05/01/2003

17.09

17.04

17.13

18.95

17.10

T

T

T

T

T

05/01/2003

05/01/2003

05/01/2003

05/01/2003

05/14/2003

17.10

17.10

18.37

18.23

16.93

T

T

T

T

T

06/19/2003

07/08/2003

07/10/2003

08/14/2003

11/20/2003

01/30/2004

16.87

16.98

16.93

17.04

17.19

16.69

S

T

T

T

T

T

17 095 N24 E18 08CCDC1 395716119593801 06/21/1973

11/21/2002

01/22/2003

03/06/2003

05/05/2003

29.00

34.35

33.87

33.50

33.30

R

S

S

S

S

06/24/2003

08/14/2003

01/30/2004

34.03

34.60

35.40

S

S

S

18 095 N24 E18 08CDDD1 395711119591501 11/20/2003

01/30/2004

dry

dry

S

S

19 095 N24 E18 15BACC1 395657119571601 11/19/2002

01/22/2003

03/06/2003

05/05/2003

06/24/2003

10.36

9.48

7.02

7.15

9.09

T

T

T

S

S

Appendix—Selected ground-water levels measured in wells, Dry Valley, west-central Nevada--Continued

Site

number 

(fig. 2)

Local identification Standard identification Water-level 

date

Water level

below

land surface

Measurement

method
Appendix—Selected ground-water levels measured in wells, Dry Valley, west-central Nevada 39

08/14/2003

11/20/2003

01/30/2004

9.89

10.51

10.03

T

T

T

20 95 N24 E18 05CCCD1 395805119593801 01/13/2004

01/30/2004

dry

dry

T

T

21 095 N24 E18 08BDDD1 395753119593201 08/21/2002

08/14/2003

01/13/2004

01/30/2004

16.85

dry

17

17.1

T

T

T

T

22 95 N24 E18 08BCBA1 395750119593701 08/21/2002

08/14/2003

01/13/2004

01/30/2004

dry

dry

dry

dry

T

T

T

T

23 95 N24 E18 08ADAD1 395745119583901 02/06/2002

08/21/2002

01/30/2004

26.83

27.35

29.39

S

T

T

Appendix—Selected ground-water levels measured in wells, Dry Valley, west-central Nevada--Continued

Site

number 

(fig. 2)

Local identification Standard identification Water-level 

date

Water level

below

land surface

Measurement

method
Since 1879, the U.S. Geological Survey has been providing maps, reports, and information to help others 

who manage, develop, and protect our Nation’s water, energy, mineral, land, and biological resources. We 

help find natural resources, and we supply scientific understanding needed to help minimize or mitigate 

the effects of natural hazards and the environmental damage caused by human activities. The results of 

our efforts touch the daily lives of almost everyone.

Berger and others—ESTIMATES OF NATURAL GROUND-WATER DISCHARGE AND CHARACTERIZATION OF WATER QUALITY IN DRY VALLEY, NEVADA, 2002-2003—USGS, SIR 2004-5155