Prepared in cooperation with the 

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Regional Ground-Water ~vapotranspiration 

and Ground-Water Budgets, 

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Professional Paper 1628 

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, Regional Ground-Water Evapotranspiration 

and Ground-Water Budgets, Great Basin, 

Nevada 

By William D. Nichols 

U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1628 

Prepared in cooperation with the 

LAS VEGAS VALLEY WATER DISTRICT and the 

NEVADA DIVISION OF WATER RESOURCES 

Cover photograph: Southern Snake Range, White Pine County, Nevada, August 1997. View east across southern 

Spring Valley from U.S. Route 93. Lincoln Canyon Creek meanders across alluvial fan in center middle ground. 

Massive cliff-forming rocks of Pole Canyon Limestone formation (Middle Cambrian age) cap Mount Washington, on far 

left of view, and ridge that descends southward (to right). Rocks of Upper Cambrian Notch Peak Limestone formation 

cap ridges on skyline at center of view. These limestones (or their stratigraphic equivalents) form part of lower 

carbonate aquifer in subsurface. Ground-water evapotranspiration from phreatophytes and associated bare soil in 

1 ,667-square-mile Spring Valley may total about 90,000 acre-feet per year. Photograph by W.O. Nichols, U.S. 

Geological Survey. 
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary 

U.S. GEOLOGICAL SURVEY 

CHARLES G. GROAT, Director 

The use of firm, trade, and brand names 

in this report is for identification purposes 

only and does not constitute endorsement 

by the U.S. Government. 

Reston, Virginia 2000 

Library of Congress Cataloging in Publication Data 

Nichols, William D. 

Regional ground-water evapotranspiration and ground-water budgets, Great Basin, 

Nevada I by William D. Nichols; prepared in cooperation with the Las Vegas Valley 

Water District aiJ.d the Nevada Division of Water Resources. 

p. em.-- (U.S. Geological Survey professional paper; 1628) 

Includes bibliographical references. 

ISBN 0-607-94492-7 

1. Groundwater flow--Nevada. 2. Evapotranspiration--Nevada 3. 

Phreatophytes--Nevada. I. Nevada. Division of Water Resources II. Las Vegas Valley 

Water District (Nev.) III. Title. IV. Series. 

GB1197.7 .N53 2000 

551.49'09793--dc21 

00-034081 

For sale by the U.S. Geological Survey, Information Services, Box 25286 

Denver Federal Center, Denver, CO 80225 
•· 

FOREWORD 

Ground water is the main source of water supply 

in much of Nevada and the Great Basin. The groundwater budget is fundamental to quantitative analyses of 

this resource. In the topographically closed valleys of 

the region, ground-water recharge is from precipitation 

and interbasin ground-water flow from adjacent valleys. The principal mechanisms of ground-water discharge are the evapotranspiration of ground water by 

phreatophytes and interbasin ground-water flow to 

adjacent ~alleys. Interbasin ground-water flow between 

adjacent valleys underscores the lack of coincidence of 

topographic and hydrologic basins throughout the 

study area, which is underlain by thick sequences of 

carbonate rocks. 

Previous Nevada ground-water budgets used 

results of field studies in California and Utah published 

in 1912 and 1932 to estimate ground-water evapotranspiration. Assuming steady-state conditions, with no 

interbasin ground-water flow to or from a topographic 

basin, ground-water recharge by precipitation was 

assumed to be equal to the estimated ground-water 

evapotranspiration. If the ground-water budget for a 

given valley proved to be imbalanced, then the difference was reconciled by assigning interbasin flow to or 

from the valley if an appropriate opposite imbalance 

existed in an adjacent valley. If interbasin ground-water 

flow could not be invoked, then the budget was either 

modified to achieve balance or was not balanced. 

The principal problem with the application of this 

method of estimating ground-water budgets lay in the 

studies upon which the estimates of ground-water 

evapotranspiration were based. The 1912 and 1932 

studies were outstanding pieces of scientific work, but 

the results were overextended when they were used 

to make regional-scale estimates of ground-:-water 

evapotranspiration. New studies of ground-water 

evapotranspiration in phreatophytic zones using 

micrometeorological methods at remote field sites 

were begun by the U.S. Geological Survey in Nevada in 

1988. The results of these studies, together with results 

of similar studies in Owens Valley, Calif., were used to 

dev~lop the relation between ground-water evapotrans- · 

piration and plant cover, which is described in Chapter 

A of this report. Using the functional form of this relation, an estimate of ground-water evapotranspiration 

can be made from an estimate of plant cover. 

Large areas in the Great Basin h!}ve phreatophytic 

zones that have a plant cover of 20 percent or less. 

Evapotranspiration rates from these areas are low, but 

the volume of ground water evapotranspired on a 

regional scale is large because of the large areas 

involved. Plant cover can be determined readily, on a 

regional scale, from Landsat data using easily calculated vegetation indices. The most commonly used vegetation index, the normalized-difference vegetation 

index, was not sufficiently sensitive to the sparse vegetation conditions that characterize the Great Basin. 

Field measurements of plant cover were used to 

develop an improved relation between plant cover and 

a modified soil-adjusted vegetation index, derived from 

satellite data, that is more sensitive to sparse vegetation. This improved functional relation between the 

vegetation index and plant cover was used together 

with the relation between plant cover and ground-water 

evapotranspiration described in Chapter A to estimate 

ground-water evapotranspiration at a regional scale as 

discussed in Chapter B. 

These tools provided the means for estimating 

ground-water evapotranspiration at regional scales. A 

study area covering nearly 15,000 mi2 and including 16 

contiguous valleys of eastern Nevada in the central 

Great Basin was selected to apply the methods 

described in Chapters A and B. Estimates of groundwater evapotranspiration were determined for each valley for 1985 and 1989, and a mean annual estimate was 

calculated. Ground-water recharge then was estimated 

by using ground-water evapotranspiration estimates· 

from 15 of the valleys to determine recharge coefficients to be applied to mean annual precipitation over 

the entire region. These efforts and the results are 

described in Chapter C. The estimates of ground-water 

recharge and discharge were used to develop groundwater budgets for each valley. As with previous studies, 

any imbalance in a given valley was assumed to be corrected by interbasin flow between adjacent valleys with 

opposite .imbalances. 

Estimates· of interbasin ground-water flow require 

reasonably good knowledge of ground-water levels, 

local geology, and the hydraulic properties of the local 

unconsolidated and consolidated aquifers, but these 

data generally are sparse throughout Nevada. The paucity of these data was nearly as great for this study as it 

was for previous studies made two or more decades 

ago. However, the present study benefited from the 

hydrologic knowledge developed by the earlier studies 

and from geologic mapping that has occurred in the 

area during the past few decades. Consequently, as 

described in Chapter C, interbasin flow to balance the 

ground-water budget for a given valley is proposed 

only in areas where it was suggested by earlier studies 

or in areas where it is supported by available geologic 

and hydrologic data. 

Foreword Ill 
IV Regional Ground-Water Evapotranspiration and Ground-Water Budgets, Great Basin, Nevada 
CONTENTS. 

Foreword......................................................................................................................................................................... III 

Chapter A. Determining Ground-Water Evapotranspiration From Phreatophyte Shrubs and Grasses as a Function 

of Plant Cover or Depth to Ground Water, Great Basin, Nevada and Eastern California ...................... Al-A14 

Chapter B. Estimating Regional Ground-Water Evapotranspiration From Phreatophytes, Great Basin, Nevada .......... Bl-B13 

Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada ............................................... Cl-C55 

COMPA_CT DISC (in pocket at back of report) 

Contains electronic versions of Professional Paper 1628 (this report) and two related publications: 

• U.S. Geological Survey Open-File Report 99-242, Data Sets and Related Information Used for Estimating Regional 

Ground-Water Evapotranspiration in Eastern Nevada, by J. LaRue Smith, Brian D. Reece, and RoseL. Medina 

• U.S. Geological Survey Fact Sheet 073-00, New Regional Ground-Water Budgets for Nevada, by William D. Nichols and 

A.S. VanDenburgh 

CONVERSION FACTORS 

Inch-pound units of measure used in this report may be converted to International System of units (SI) by using the following factors 

Multiply By To obtain 

Area 

acre 4,047 square meter 

square foot (ft2

) 0.09290 square meter 

Length 

foot (ft) 0.3048 meter 

inch (in.) 2.540 centimeter 

mile (mi) 1.609 kilometer 

square mile (mi2

) 2.590 square kilometer 

Volume 

acre-foot (acre-ft) 1,233 cubic meter 

acre-foot per year (acre-ft/yr) 1,233 cubic meter per year 

Flow rate 

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

foot per year (ft/yr) 0.3048 meter per year 

foot squared per day (ft2

/d) 0.09290 meter squared per day 

Temperature: Degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) by using the formula °C = [°F - 32]/1.8. 

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. 

CONTENTS V 
.. Chapter A. Determining Ground-Water Evapotranspiration From Phreatophyte Shrubs and Grasses as a 

Function of Plant Cover or Depth to Ground Water, 

Great Basin, Nevada and Eastern California 

By William D. Nichols 

AI 
Title-page photograph: Southern Ruby Valley, Elko County, Nevada, July 1996. View west toward southern Ruby Mountains. 

Sharp color contrast marks boundary between phreatophyte greasewood (bright green) and non-phreatophyte sagebrush (dark 

green and foreground). Ruby Marsh is in middle distance at base of mountains. Phreatophytes and associated bare soil on floor 

of Ruby Valley may yield almost 170,000 acre-feet of ground-water evapotranspiration per year. Photograph by William D. 

Nichols, U.S. Geological Survey. 

All Chapter A. Determining Ground-Water Evapotranspiration From Phreatophyte Shrubs and Grasses and From Bare Soil 
CONTENTS 

Abstract.................................................................................................................................................................................. A1 

Introduction............................................................................................................................................................................ A 1 

Purpose and Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A2 

Previous Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A2 

Data and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A3 

Ground-Water Evapotranspiration From Phreatophyte Shrubs and Grasses and From Associated Bare Soil...................... A6 

Evapotranspiration as a Function of Plant Cover....................................................................................................... A6 

Evapotranspiration as a Function of Depth to Ground Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A 7 

Relation Between Plant Cover and Depth to Ground Water ...................................................................................... A10 

Ground-Water Evapotranspiration, Phreatophyte Plant Cover, and Depth to Ground Water. ............................................... A10 

Summary and Conclusions .................................................................................................................................................... A13 

References Cited ............................................................. :...................................................................................................... A 13 

FIGURES 

Al. Map showing location of study areas and field sites, Nevada and California ......................................................... A4 

A2-A4. Graphs showing ground-water evapotranspiration from phreatophyte shrubs and grasses and associated 

bare soil as related to plant cover: 

A2. May through September evapotranspiration................................................................................................ A 7 

A3. October through April evapotranspiration................................................................................................... A8 

A4. Annual evapotranspiration........................................................................................................................... A8 

AS-A 7. Graphs showing ground-water evapotranspiration from phreatophyte shrubs and grasses and associated 

bare soil as related to depth to ground water: 

AS. May through September evapotranspiration................................................................................................ A9 

A6. October through April evapotranspiration................................................................................................... A9 

A 7. Annual evapotranspiration ................................................................................................ : .......................... A 10 

A8-A9. Graphs showing: 

AS. Relation between plant cover and depth to ground water. ........................................................................... A12 

A9. Annual ground-water evapotranspiration from phreatophyte shrubs and grasses and associated bare soil 

and the approximate depth to ground water .............................................................................................. A 12 

TABLES 

A 1. General information for field sites, Great Basin study areas . ........ ... . . . . ... .. . . . . ... . . . . ....... .......... .... .. . . . . . .... ... . . . . ........... A5 

A2. Vegetation characteristics and depth to ground water at field sites, Great Basin study areas................................. AS 

A3. Seasonal and annual rates of ground-water evapotranspiration at field sites, Great Basin study areas.................. A 7 

A4-AS. Coefficients for equation for estimating ground-water evapotranspiration as a function of: 

A4. Plant cover . . ...... ........ ....... ....... ...... ... . . . ....... ...... ....... ....... ........ ...... ......... ... . . . ......... ... .. . . . ........... ............ ..... .. . . A8 

AS. Depth to ground water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A9 

CONTENTS Alii 
AIV Chapter A. Determining Ground-Water Evapotranspiration From Phreatophyte Shrubs and Grasses and From Bare Soil 
Chapter A. Determining Ground-Water Evapotranspiration From Phreatophyte Shrubs and Grasses as a 

Function of Plant Cover or Depth to Ground Water, Great 

Basin, Nevada and Eastern California 

By William D. Nichols 

ABSTRACT 

Ground-water evapotranspiration data from 

five sites in Nevada and seven sites in Owens 

Valley, California, were used to develop equations 

for estimating ground-water evapotranspiration as 

a function of phreatophyte plant cover or as a function of the depth to ground water. Equations are 

given for estimating mean daily seasonal and 

annual ground-water evapotranspiration. The 

equations that estimate ground-water evapotranspiration as a function of plant cover can be used to 

estimate regional-scale ground-water evapotranspiration using vegetation indices derived from satellite data for areas where the depth to ground 

water is poorly known. Equations that estimate 

ground-water evapotranspiration as a function of 

the depth to ground water can be used where the 

depth to ground water is known, but for which 

information on plant cover is lacking. 

INTRODUCTION 

Ground-water evapotranspiration by phreatophytes and associated bare soil is an important component of the water budget in arid and semiarid regions. 

In many valleys of the Great Basin, ground-water 

evapotranspiration is the only mechanism of groundwater discharge or represents the major component of 

discharge in the ground-water budget. Estimating 

ground-water evapotranspiration, especially at regional 

scales, has been difficult at best. 

Estimates of ground-water evapotranspiration 

most commonly have been made either for specific 

plant types using evapotranspiration-tank data (Lee, 

1912; Blaney and others, 1930, 1938; White, 1932; 

Young and Blaney, 1942; Gatewood and others, 1950; 

Robinson, 1970), or for small areas of native rangeland 

or riparian vegetation based on field measurements 

using micrometeorological techniques (Weeks and others, 1987; Duell, 1990; Malek and others, 1990). These 

estimates were based on measured evapotranspiration 

derived from energy budgets and were then extrapolated to larger areas of similar vegetation. 

The phreatophytes of interest are those of the salt 

desert plant community, which include saltgrass (Distich/is spicata var. stricata), iodinebush (Allenrolfea 

occidentalis, also called pickleweed), and saltsage 

(Atriplex tridentata); and those of the shadscalegreasewood plant community, which include greasewood (Sarcobatus vermiculatus), shadscale (Atriplex 

confertifolia), saltbush (Atriplex canescens, also 

known as chamiso, and A triplex torreyi), spiny hopsage 

( Grayia spinosa ), winterfat ( Ceratoides lanata ), and, 

where soils and ground water are less saline, rabbitbrush ( Chrysothamnus nauseosus) and big sagebrush 

(Artemisia tridentata). 

Saltgrass, the principal phreatophyte of the salt 

desert community, commonly grows where the depth to 

ground water is less than about 8 ft, but has been 

reported to grow in areas where the water table is as 

much as 12ft deep (Blaney and others, 1933, p. 50). 

Plants of the shadscale-greasewood community occur 

where depths to water range from about 3 ft to as much 

as 65ft (Robinson, 1958). Greasewood, the principal 

phreatophyte of this plant community, occurs in areas 

where the depth to ground water ranges from about 5 ft 

to 35 ft and perhaps as much as 60 ft (Robinson, 1958, 

p. 39). Saltbush is found where the water table is from 

about 8 ft to as much as 62 ft below land surface (Robinson, 1958, p. 33). Rabbitbrush grows where the depth 

to wat~r is less than about 35ft (Robinson, 1958, p. 34). 

ABSTRACT A1 
Big sagebrush, although commonly not considered to 

be a phreatophyte, has been observed growing in many 

areas in association with rabbitbrush where the water 

table is as much as 12 ft below land surface (Mozingo, 

1987, p. 271). Under these conditions of shallow 

ground water, big sagebrush is assumed to be a 

phreatophyte. 

Purpose and Scope 

The present study extends earlier work on 

ground-water evapotranspiration by phreatophytes 

(Nichols, 1994) and this chapter presents equations for 

estimating ground-water evapotranspiration from 

phreatophyte grasses and shrubs and from associated 

bare soil in areas of shallow ground water as a function 

of plant cover or depth to ground water. The equations 

previously proposed (Nichols, 1994) required knowledge of the amount of plant cover as well as the depth 

to ground water. Depth to ground water commonly is 

not well known at regional scales in many areas, such 

as the Great Basin, and is difficult to define in the 

absence of a sufficient number of wells. Equations proposed by the present study that correlate ground-water 

evapotranspiration with plant cover can be used to estimate ground-water evapotranspiration at regional 

scales using remotely sensed vegetation index data, 

provided correlation can be made between plant cover 

and satellite-data-derived vegetation indices. The equations that describe ground-water evapotranspiration as 

a function of depth to ground water are appropriate for 

use, in combination with the equations given by 

Nichols (1994), in numerical models of ground-water 

flow and for other applications where the depth to 

ground water is known. 

Previous Studies 

All evapotranspiration-tank studies of groundwater evapotranspiration used similar techniques. 

Tanks for some of the studies were placed in excavations and filled with the excavated soil; the soil surface 

in the tank either received transplanted greasewood, 

rabbitbrush, or other shrubs or was covered with saltgrass sod (Lee, 1912; White, 1932). For other studies, 

such as that at Santa Ana, Calif. (Blaney and others, 

1930), the tank was driven into the ground so that 

it contained undisturbed soil and saltgrass. This 

method required an excavation around the tank as 

work proceeded. The filled tank then was lifted out of 

the excavation, the bottom of the tank was sealed, and 

the tank was placed in an excavation at the study site. 

The "tanks" employed by Robinson (1970) were not 

tanks as such, but rather were rectangular excavations 

measuring 30ft by 30ft by 10.5 ft deep, 20ft by 20ft 

by 10 ft deep, and 10 ft by 10 ft by 7 ft deep, that were 

lined with a heavy plastic membrane. In all the studies, 

the evapotranspiration tanks were fitted with one or two 

water-reservoir tanks. The reservoir tanks were used to 

maintain a constant water level in the evapotranspiration tank and to provide a storage tank to which water 

could be added in measured volumes. A record of volume added and volume remaining in the tanks provided 

a measure of the volume of evapotranspiration from the 

tank. 

The pioneering study of evapotranspiration from 

saltgrass by Lee (1912) seemed to demonstrate a clear 

relation between ground-water evapotranspiration and 

depth to ground water. Subsequent studies by Blaney 

and others (1930, 1938) and studies summarized by 

Young and Blaney (1942) produced similar results, 

but analysis of these data (Weeks and others, 1987) 

demonstrated that depth to ground water does not 

adequately define a unique relation to ground-water 

evapotranspiration by saltgrass. None of these tank 

studies provided a measure of the amount of vegetation, such as density or leaf area index. 

Evapotranspiration-tank experiments by White 

(1932) in the Escalante Desert near Milford, Utah, 

and Robinson ( 1970) in the Great Basin Desert near 

Winnemucca, Nev. (fig. A1), included evapotranspiration measurements for greasewood and rabbitbrush. 

These studies, as well as that of Gatewood and others 

( 1950), attempted to relate measured evapotranspiration to the amount of vegetation present and to the 

depth to ground water. White (1932) developed a relation between the observed volume of ground-water 

evapotranspiration and the weight of dry biomass produced. White concluded a general relation existed 

between the depth to ground water and ground-water 

evapotranspiration by greasewood by assigning one 

rate of evapotranspiration to areas where ground water 

was less than 8 ft below land surface and a lower evapotranspiration rate to areas where ground water was 

greater than 8ft deep. He also concluded that greasewood, rabbitbrush, and shadscale had similar rates of 

ground-water evapotranspiration. Gatewood and others 

( 1950) and Robinson ( 1970) each developed measures 

of ground-water evapotranspiration as related to the 

volume density of vegetation, but each used different 

A2 Chapter A. Determining Ground-Water Evapotranspiration From Phreatophyte Shrubs and Grasses and From Bare Soil 
methods for determining volume density. The conclusions reached by Robinson ( 1970) are equivocal and 

not easily summarized, but suggest a relation between 

ground-water evapotranspiration and both the depth to 

ground water and the volume of biomass. None of these 

studies developed methods that can be applied systematically to estimate ground-water evapotranspiration by 

phreatophytes. 

Energy budget studies, such as those by Gay 

and Fritschen ( 1979), Weeks and others ( 1987), Duell 

(1990), Malek and others (1990), and Nichols and 

others ( 1997), typically used either the Bowen ratio 

method (Tanner, 1960) or the eddy correlation method 

(Businger and others, 1967) to calculate evapotranspiration. Results of these studies apply to an area within 

about 300 to 500 ft of the point of measurement. 

Evapotranspiration measured by these studies commonly includes not only ground-water evapotranspiration, but water removed by evapotranspiration of any 

recent precipitation. 

Ground-water transpiration by phreatophyte 

shrubs in the Great Basin was estimated by Nichols 

(1994) using an energy-combination model that solved 

the energy budget separately for the soil and the canopy. Nichols ( 1994) developed a functional relation 

between the transpiration of ground water, and the 

depth to ground water, plant density, and leaf area 

index. This approach did not include estimates of 

ground-water evaporation from the bare soil associated 

with the phreatophyte shrubs, and provided only for 

estimates of ground-water transpiration during the 

summer months, May through September. The results, 

as presented (Nichols, 1994 ), implied that leaf area 

index was independent of the depth to ground water. 

DATA AND METHODS 

Energy budget studies of ground-water evapotranspiration from native rangelands were done in 

Nevada from 1988 through 1994 (Nichols, 1994; 

Nichols and others, 1997). The field sites were in the 

Smoke Creek Desert, Smith Creek Valley, Railroad 

Valley (Nichols, 1994), and the Ash Meadows area 

(Nichols and others, 1997). Energy budget data for 

seven field sites in the Owens Valley of California 

(Duell, 1990) also were used in this study. Site locations are shown in figure A1 and site descriptions 

are given in tables A 1 and A2. Methods of data collection and analysis for the Nevada sites have been discussed by Nichols ( 1994) and for the California sites by 

Duell (1990). Evapotranspiration for the Nevada sites 

was determined using the energy budget - Bowen ratio 

method (Tanner, 1960). For the California sites, Duell 

( 1990, p. E25) determined evapotranspiration using 

either the Bowen ratio method or from eddy correlation 

data using a direct-measurement method, a residual 

method, or both; whenever two methods were used, the 

results were averaged for the present study. 

The present analysis assumed, as have previous 

investigators, that ground-water evapotranspiration by 

phreatophytes is related to depth to ground water and 

plant biomass, but also assumed that biomass is a function of the depth to ground water. Factors other than the 

depth to ground water, such as soil type and soil and 

water chemistry, also may affect the biomass of any 

given area. However, in general, the shallower the 

depth to ground water, the more dense is the phreatophyte biomass. The amount of phreatophyte biomass, 

not the depth to ground water, is the principal indicator 

of ground-water evapotranspiration. If phreatophyte 

biomass is a function of the depth to ground water, and 

if ground-water evapotranspiration depends on 

phreatophyte biomass, then only the relation between 

phreatophyte biomass and ground-water evapotranspiration needs to be determined. 

The measure of phreatophyte biomass used in this 

study is plant cover, which was determined from plant 

density and leaf area index. Plant density (d) was measured and is the ratio of the horizontal length of plants 

per length of measured transect, usually a length of 

300 ft (Smith and others, 2000). Shrub leaf area index 

(LA/p) is the leaf area per unit ground area for individual shrubs along the measured plant-density transect 

and is a commonly used measure that typically ranges 

from 0 to 4, but has been reported as high as 10 for cereals with vertical leaf habits (Monteith and Unsworth, 

1990). The LA/p used for this analysis was the measured or estimated annual maximum plant leaf area 

index at each field site ((LA/p)max)· For shrubs and 

grasses at the Nevada field sites, and generally throughout the Great Basin, the (LA/p )max is attained in midJune to early July. The leaf area index (LA/) at the 

Nevada field sites was determined by measuring the 

assumed (LA/p)max of individual shrubs (Groeneveld 

and Warren, 1992) along a measured transect, calculating a weighted average of the (LA/p )max based on the 

percent of each shrub species along the transect 

(LA/p )max, and multiplying (LA/p )max by the density of shrubs along the transect (eq. 1). For the Owens 

Valley sites, the LA/ was estimated based on the plant 

DATA AND METHODS A3 
.tJ·;,v·· 

. ·~ l ~-· 1 OREGON J • \ -~ \. IDAHO _ - - - - •• 

f.tv_....t- .. r --.'- - --- ~rv·. ) l ··'---=)~S·v.. 1 , .. 

( Winnemucca. •\ 

..,__r··\. • Eiko salt Lake City• 

~+ :''oke C<eek Dewct 

. . 

,·r ~-

~ • • Reno 

J • Cacson c;ty (l. . f 

j 

c . ~ ( I 

. ( +12 : 

( .. .~ il road Valley 

. ._____ .. r. (northern part) 

• MBfor~· j . 

:1 / ;· 

~:\ ~ 

~ 

.. \ ') 

.. /··J ·. 

\<>~ !•\ ' c;i) ~ .. l, 0 "k 

6+: ~< ~£..: 7+ «- ~() -•~ Owens 0..<'\ ':<! Independence .. 9 . V 11 • rA. • . a ey 'l'l: 

\ "'· '1 . j 

y· 

10,11 

t Ash Meadows 

Las Vegas • 

~· ~ ~. • ,....__ • ·~ r"'* . • ' ~ • 

'"' ··j ~· 

Base from U.S. Geological Survey digital data, 1:100,000, 1978-88 

Universal Transverse Mercator Projection, Zone 11 

0 50 100 150 

t.!J ~: 

~·· 

I : 

• • _bl- ARIZONA 

---

I EXPLANATION 

- • • - Boundary of Great Basin-Modified 

from Harrill and others {1988) 

Topographic valley boundary 

2 • Study-area field site-Numbers 

coincide with those given 

in table A1 

200 MILES 

0 50 100 150 200 KILOMETERS 

Figure A 1. Location of study areas and field sites, Nevada and California. Numbers refer to locations given in table A 1. 

A4 Chapter A. Determining Ground-Water Evapotranspiration From Phreatophyte Shrubs and Grasses and From Bare Soil 
Table A 1. General information for field sites, Great Basin study areas 

[NR: Altitude not reported, but all sites are between 3,800 and 4,200 feet above sea level (Duell, 1990, p. E2).] 

Altitude Site Latitude Longitude 

(fig. A1) Location (oN) (oW) (feet above Dates of data collection Source 

sea level) 

Smoke Creek Desert, Nev. 40.534 119.818 3,907 June-Sept. 1991 Nichols, 1994 

2 Smith Creek Valley, Nev. 39.330 117.512 6,046 May-Sept. 1989 Nichols, 1994 

3 Owens Valley, Calif., site A 37.400 118.383 NR Jan. 1984-0ct. 1985 Duell, 1990 

4 Owens Valley, Calif., site C 37.317 118.367 NR Jan. 1984-0ct. 1985 Duell, 1990 

5 Owens Valley, Calif., site E 37.250 118.333 NR Jan. 1984-0ct. 1985 Duell, 1990 

6 Owens Valley, Calif., site F 37.108 118.250 NR Jan. 1984-0ct. 1985 Duell, 1990 

7 Owens Valley, Calif., site G 36.983 118.225 NR Jan. 1984-0ct. 1985 Duell, 1990 

8 Owens Valley, Calif., site J 36.842 118.183 NR Jan. 1984-0ct. 1985 Duell, 1990 

9 Owens Valley, Calif., site L 36.783 118.183 NR Jan. 1984-0ct. 1985 Duell, 1990 

10 Ash Meadows, Nev., site 1 36.482 116.332 2,255 March-Dec. 1994 Nichols and others, 1997 

11 Ash Meadows, Nev., site 2 36.482 116.335 2,252 March-Dec. 1994 Nichols and others, 1997 

12 Railroad Valley, Nev. 38.503 115.769 4,757 June 1992-Dec. 1994 Nichols, 1994 

Table A2. Vegetation characteristics and depth to ground water at field sites, Great Basin study areas 

[E, Estimated.] 

Site 

(fig. A1, Most common plant types 

table A1) 

Greasewood, saltbush, sagebrush 1 

2 Greasewood, rabbitbrush 

3 Alkali sacaton, russian thistle, bassia, saltgrass 2 

4 Saltgrass, rabbitbrush, alkali sacaton, saltbush, greasewood 2 

5 Rabbitbrush, alkali sacaton, mormon tea, sagebrush, saltgrass, greasewood 2 

6 Saltgrass, greasewood, alkali sacaton, saltbush 2 

7 Saltgrass, alkali sacaton, rabbitbrush, greasewood 2 

8 Saltbush, alkali sacaton, rabbitbrush, greasewood 2 

9 Saltgrass, alkali sacaton, wiregrass2 

10 Salt grass 

11 Saltgrass, wiregrass 

12 Greasewood, saltbush 

1 Perched ground water. Depth to water table is 20 feet. 

2 From Duell (1990). 

3 From Groeneveld and Warren (1992). 

Plant 

density 

(d) 

0.17 

.21 

.42 

.35 

.26 

.24 

.33 

.50 

3.73 

.60 

.95 

.13 

Maximum Minimum depth 

plant leaf to ground water 

area index (feet below 

(LA/p) land surface) 

2.7 8.9 

3.4 5.9 

2.0E 10.5 

l.OE 10.2 

1.8E 10.2 

1.5E 7.9 

1.9E 7.2 

1.8E 4.6 

2.6 .0 

2.8 1.6 

3.5 .0 

1.4 5.9 

DATA AND METHODS AS 
density and plant species reported by Duell (1990) and 

limited LA/p values given by Groeneveld and Warren 

(1992). The leaf area index, LA/, is given by 

LA/ = d(LA/p )max (1) 

where dis measured plant density, and 

(LA/p )max is the weighted-average maximum leaf 

area index of shrubs along the measured 

plant-density transect. 

The leaf area index, LA/, then was normalized by 

dividing by 4, the assumed maximum value for LA/; the 

resulting index, which is referred to as plant cover, Cp, 

is given by 

LA/ 

Cp = 4· (2) 

Studies at field sites 1 and 2 in 1989 and 1991 followed several years of drought. Winter precipitation in 

western Nevada was sparse, and was evapotranspired by 

early to mid-May. The measured mean daily evapotranspiration from late May or early June to early September 

at each site was assumed therefore to represent mean 

daily ground-water evapotranspiration from phreatophyte shrubs for May through September. Field observations have shown that summer convective-storm 

precipitation is evapotranspired within 5 to 7 days. Consequently, evapotranspiration for periods of 5 to 7 days 

following convective storms was not included in the 

estimation of mean daily ground-water evapotranspiration. 

Studies in 1994 at field sites 10 and 11 in the Ash 

Meadows area in southern Nevada also followed an 

extended dry period. Precipitation was not measured at 

the field sites; the nearest U.S. Weather Service stations 

are about 10 mi north and about 15 mi southeast of the 

study sites. On the basis of data from these stations, 0.65 

inch of precipitation fell at locations near the study sites 

during the last 3 months of 1993 and as much as 1.44 

inches fell during January and February 1994. No precipitation fell at field sites 10 and 11 during 1994 after 

February. Therefore, evapotranspiration from May 1 

through September 30 at these sites was assumed to be 

derived entirely from ground water. The October 

through April evapotranspiration from the Ash Meadows sites was calculated using the January through 

J April and October through December 1994 data; Janu-. 

ary and February precipitation was subtracted from the 

October to April total before calculating the mean daily 

evapotranspiration. 

Duell (1990) measured precipitation only at field 

sites 4, 6, and 9 (Duell's sites C, F, and L; Duell, 1990). 

Evapotranspiration from Owens Valley field sites at 

which precipitation data were not collected have been 

corrected by subtracting precipitation recorded at the 

nearest field site. Evapotranspiration at field sites 3 and 

5 (Duell's sites A and E) has been corrected by subtracting precipitation measured at field site 4. Evapotranspiration at field site 7 (Duell's site G) has been corrected 

by subtracting precipitation measured at field site 6, and 

evapotranspiration from field site 8 (Duell's site J) has 

been corrected by subtracting precipitation measured at 

field site 9. 

Duell (1990, p. E25) presented data for January 

1984 through October 1985. For the present study, May 

through September evapotranspiration (table A3) is the 

mean of May-September 1984 and May-September 

1985 evapotranspiration reported by Duell ( 1990). 

October through April evapotranspiration (table A3) 

is for October through December 1984 and January 

through April 1985 (table A3). 

GROUND-WATER EVAPOTRANSPIRATION 

FROM PHREATOPHYTE SHRUBS AND 

GRASSES AND FROM ASSOCIATED BARE 

SOIL 

Evapotranspiration as a Function of Plant 

Cover 

Measurements of May through September groundwater evapotranspiration from shrubs and saltgrass field 

sites in Nevada (sites 1, 2, 10, 11, and 12, fig. A2, tables 

A1 and A2) were the foundation for the analysis. However, because only two field sites (11 and 12) included 

data for October through April, data from the Owens 

Valley field sites were included so that the results of the 

analysis could extend to winter and annual estimates of 

ground-water evapotranspiration. May-September (153 

days), October-April (212 days), and annual groundwater evapotranspiration (table A3) are plotted as a 

function of plant cover at each study site (figs. A2-A4 ). 

Least-squares analysis indicated the curve that best 

describes the data is an exponential equation of the form 

where ET is mean daily May-September, mean daily 

October-April, annual mean daily, or annual 

total ground-water evapotranspiration. 

Coefficients a, b, and c for estimating seasonal and 

annual ground-water evafotranspiration and the coefficient of determination, r , for each data set in table A3 

are given in table A4. 

A6 Chapter A. Determining Ground-Water Evapotranspiration From Phreatophyte Shrubs and Grasses and From Bare Soil 
Table A3. Seasonal and annual rates of ground-water evapotranspiration at field sites, Great Basin study areas 

Site 

Mean daily ground-water Mean annual 

(fig. A1, 

evapotranspiration (feet per day) ground-water 

table A1) May- October- evapotransSeptember April Annual piration (feet) 

1 0.0054 

2 .0080 

3 .010 0.0021 0.0054 1.97 

4 .0043 .00078 .0023 .839 

5 .0049 .0022 .0033 1.20 

6 .0024 .00058 .0013 .474 

7 .0070 .0020 .0041 1.46 

8 .010 .0024 .0055 2.04 

9 .014 .0028 .0075 2.73 

10 .012 .0029 .0067 2.45 

11 .013 .0025 .0069 2.52 

12 .0013 

Equation 3 was selected from several equations 

that equally well described the evapotrans~irationplant cover relation (all equations had an r ~ 0.96). 

This equation was chosen because it is equivalent to 

the equation used to calculate saturation vapor pressure 

as a function of temperature (Arya, 1988, p. 52). 

> C( 

0 

a: 

w 

D. 

... 

w 

w 0.015 LL 

~ 

z 

0 

~ a: 

a: 

~ 0.010 

C( 

a: 

b 

D. 

C( 

> w 

a: 

w 

0 

~ z 

:::l 

0 

a: 

CJ 

0.005 

• Nevada data 

o California data 

Equation 3, therefore, may have a physical basis in the 

calculation of ET, compared to the strictly empirical 

relation described by the other candidate equations. 

Evapotranspiration as a Function of Depth to 

Ground Water 

The same ground-water evapotranspiration data 

(table A3) used in the above analysis are plotted against 

the depth to ground water (table A2) at each of the field 

sites in figures A5-A7. In all cases, the data are best 

described by a linear equation 

ET = a+ ~Zw 

for Zw<lOft, 

(1) 

where ET is mean daily May-September, mean daily 

October-April, annual mean daily, or annual 

total ground-water evapotranspiration, and 

Zw is depth to ground water, in feet. 

Coefficients a and ~ for estimating seasonal and 

annual ground-water evafotranspiration and the coefficient of determination, r , for each data set in table A3 

are given in table A5. 

09 11 

o~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 

PLANT COVER (Cp) 

Figure A2. May through September ground-water evapotranspiration from phreatophyte shrubs and 

grasses and associated bare soil as related to plant cover. Numbers refer to field sites shown on figure 

A 1 and described in table A 1 . 

GROUND-WATER EVAPOTRANSPIRATION FROM PHREATOPHYTE SHRUBS AND GRASSES AND ASSOCIATED BARE SOIL A7 
z 

0 

~ a: 

0:: 

UJ 

Z> 

<tc:t 

a::o 

1-a:: Ow 

~Q. 

>tww 

a::W 

WLL 

t-Z <t3: 

6 

z 

::::) 

0 

a: 

Cl 

0.004 

0.002 

.... Nevada data 

o California data 

•10 9 

11 

o~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 

PLANT COVER (Cp) 

Figure A3. October through April ground-water evapotranspiration from phreatophyte shrubs and 

grasses and associated bare soil as related to plant cover. Numbers refer to study sites shown on figure 

A 1 and described in table A 1. 

0 

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 

PLANT COVER (Cp) 

0.8 0.9 

0.008 > 

<t 

0 

0.006 

a: 

w 

Q. 

1-

w 

w 

LL 

~ 

z 

0 

i= 

<t 

a: 

0:: 

0.004 ~ 

0.002 

0 

1.0 

<t 

a: 

1-

0 

Q. 

<t 

> w 

a: 

w 

1-

<t 

3: 

6 

z 

::::) 

0 

a: 

Cl 

Figure A4. Annual ground-water evapotranspiration from phreatophyte shrubs and grasses and associated bare soil as related to plant cover. Numbers refer to study sites shown on figure A 1 and 

described in table A 1 . 

Table A4. Coefficients for equation for estimating ground-water evapotranspiration 

as a function of plant cover 

Data set Coefficients 

r2 

(table A3) a b c 

May-September, feet per day -4.13 -0.199 -0.263 0.973 

October-April, feet per day -5.82 -.203 -.483 .842 

Annual, feet per day -4.77 -.214 -.358 .975 

Annual, feet 1.13 -.215 -.363 .975 

A8 Chapter A. Determining Ground-Water Evapotranspiration From Phreatophyte Shrubs and Grasses and From Bare Soil 
o California data 

08 03 

2 3 4 5 6 7 8 9 10 11 

DEPTH TO GROUND WATER, IN FEET 

Figure AS. May through September ground-water evapotranspiration from phreatophyte shrubs and 

grasses and associated bare soil as related to depth to ground water. Numbers refer to field sites 

shown on figure A 1 and described in table A 1. 

z 0.006 0 

~ a: 0.005 0:: o California data 

fJ) 

Z> 

<(<( 

a:c 0.004 

t-a: Ow 

C.. c.. <( .... 0.003 

>w 

ww a:LL 

w 0.002 t-Z <(-

08 

07 

c == 0.001 z 

~ 06 04 

0 

a: 0 " 0 2 3 4 5 6 7 8 9 10 11 

DEPTH TO GROUND WATER, IN FEET 

12 

Figure A6. October through April ground-water evapotranspiration from phreatophyte shrubs and 

grasses and associated bare soil as related to depth to ground water. Numbers refer to field sites shown 

on figure A 1 and described in table A 1. 

Table AS. Coefficients for equation for estimating ground-water 

evapotranspiration as a function of depth to ground water 

Data set Coefficients 

(table A3) a ~ 

May-September, feet per day 0.0125 -0.00078 

October-April, feet per day .00276 -.000121 

Annual, feet per day .00715 -.000394 

Annual, feet 2.61 -.143 

0.505 

.415 

.627 

.626 

12 

GROUND-WATER EVAPOTRANSPIRATION FROM PHREATOPHYTE SHRUBS AND GRASSES AND ASSOCIATED BARE SOIL A9 
3.00 1-

w 

w 

u.. 

~ 

z ... Nevada data 

0 

i= o California data <( 

a: 

0:: 

en 

z 2.00 03 

<( 

a: 

1-

0 

a.. 

<( 

> w 

a: 

w 

1-

<( 

3F 

c 1.00 z 

:-, 04 0 

a: 

(!) 

...J 

<( 06 :-, 

z 

z 

<( 

o~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 

0 2 3 4 5 6 7 8 9 10 11 12 

DEPTH TO GROUND WATER, IN FEET 

Figure A7. Annual ground-water evapotranspiration from phreatophyte shrubs and grasses and associated bare soil as related to depth to ground water. Numbers refer to field sites shown on figure A 1 and 

described in table A 1 . 

The correlation between ground-water evapotranspiration and depth to ground water is good except 

at field sites 3, 6, and 12. Duell (1990, p. E6) reported 

that ground-water levels were recorded at wells within 

500 ft of each of his field sites. It may be that the depth 

to ground water recorded for field sites 3 and 6 is not 

representative of the depth to water beneath the sites or 

it may be that evapotranspiration rates are underestimated at field site 6 and overestimated at field site 3. 

Ground-water evapotranspiration at field site 12 is 

anomalously low for the depth to ground water at the 

site, indicating something other than depth to ground 

water is influencing the amount of plant cover, and 

hence the amount of ground-water evapotranspiration, 

at the site. 

Relation Between Plant Cover and Depth to 

Ground Water 

The good correlation between ground-water 

evapotranspiration and plant cover and between 

ground-water evapotranspiration and depth to ground 

water strongly suggests a correlation between plant 

cover and the depth to ground water, the assumption 

upon which the foregoing analysis was based. Plant 

cover is plotted against the annual minimum depth to 

ground water at each study site in figure A8. The data 

shown in figure A8 are best described (r2 = 0.837) by 

an exponential equation of the form 

where Cp is the plant cover, in this case, that reasonably may be expected to occur for a given 

depth to ground water, and 

Zw is depth to ground water, in feet. 

GROUND-WATER EVAPOTRANSPIRATION, 

PHREATOPHYTE PLANT COVER, 

AND DEPTH TO GROUND WATER 

The good correlation between plant cover and 

ground-water evapotranspiration and between plant 

cover and depth to ground water combined with the 

weaker correlation between ground-water evapotranspiration and depth to ground wat~r strongly suggest 

that plant cover is the major factor in determining 

ground-water evapotranspiration by phreatophytes in 

A 10 Chapter A. Determining Ground-Water Evapotranspiration From Phreatophyte Shrubs and Grasses and From Bare Soil 
areas of shallow ground water. Even in areas of very 

shallow ground water, ground-water evapotranspiration is small if plant cover is sparse, such as at site 12. 

The equations developed by this study provide a 

consistent, or uniform, method for estimating groundwater evapotranspiration from phreatophyte shrubs and 

grasses and from associated bare soil in the Great 

Basin; they are not intended to be used to estimate 

ground-water evapotranspiration by saltcedar, willows 

and other trees, or from riparian vegetation. Groundwater evapotranspiration estimated with the equations 

proposed in the present study includes evaporation of 

ground water from the water table through bare soil and 

transpiration of ground water by phreatophyte shrubs 

and grasses. Those equations proposed in the earlier 

study (Nichols, 1994) estimated only the ground water 

transpired by phreatophyte shrubs and implied that LA/ 

was independent of the depth to ground water. 

Mean daily and annual evapotranspiration estimated by the equations presented here may seem large 

in comparison to estimates suggested by earlier studies, 

but these values must be understood in the context of 

the depth to ground water for which they are appropriate (fig. A9). Annual ground-water evapotranspiration 

greater than about 1.15 ft/yr applies to areas where the 

depth to ground water is less than about 10 ft. This 

occurs commonly in grassy and marshy areas near 

springs that represent a small part of the hydrographic 

areas and basins throughout most of the Great Basin. 

Ground-water levels commonly are 15 to 25ft deep 

beneath most rangeland areas with phreatophyte shrubs 

such as greasewood and rabbitbrush. Annual groundwater evapotranspiration in these areas will range from 

about 0.16 to about 0.50 ft/yr. 

Correlating plant cover with depth to ground 

water is not entirely straightforward. Factors other than 

the depth to the water table influence plant cover at any 

given location. For example, the depth to the water 

table at field site 1 in the Smoke Creek Desert is 20 ft, 

but there is a perched saturated zone at about 9 ft. The 

plant cover at this site fits the proposed curve (fig. A8) 

better at a depth to ground water of about 10 ft than it 

does a depth of 20 ft. However, unknown factors at field 

site 12 in Railroad Valley have resulted in a plant cover 

at the site of only about 0.045 ( 4.5 percent) in an area 

where the depth to ground water is 5.9 ft; this plant 

cover is more consistent with a depth to ground water 

of about 30 to 35ft. Consequently, the relation defined 

by equation 5 describes the plant cover that might be 

expected for the indicated depth to the water table in the 

absence of other factors that affect the actual plant 

cover. 

The equations presented here and the data upon 

which they are based provide insights into the processes of ground-water evapotranspiration by phreatophyte shrubs and grasses in the Great Basin. This 

process is shown by the curve in figure A4. Maximum 

ground-water evapotranspiration occurs in areas where 

the plant cover ranges from about 0.50 to 0.65 (50 percent to 65 percent), and areas with a plant cover of only 

about 0.40 ( 40 percent) discharge as much ground 

water by evapotranspiration as areas where the plant 

cover is 1.00 (100 percent). These conclusions, 

although not necessarily intuitive, are supported by 

observations at field sites 10 and 11 (tables A2 and A3) 

in the Ash Meadows area in southern Nevada (Nichols 

and others, 1997). Field site 10 has a plant cover of 

about 0.42 (42 percent) leaving about 58 percent of the 

area as bare soil. The minimum depth to ground water 

at the site was about 1.6 ft. Field site 11 had a plant 

cover of about 0.83 (83 percent) with ground water at 

or slightly above land surface during winter months. In 

spite of the large difference in the plant cover between 

the two field sites, the annual ground-water evapotranspiration from each site is similar. A comparison of daily 

ground-water evapotranspiration for the two sites 

(Nichols and others, 1997) shows that ground-water 

evapotranspiration increased more rapidly in the spring 

at field site 10 than at field site 11. The salt grass at field 

site 10 was a vigorous green by mid-May; at field site 

11, it did not become green and show evidence of 

growth until late May, although the wire-grass became 

green much earlier. The difference in ground-water 

evapotranspiration at the two field sites during this time 

reflects the greater evaporation of shallow ground 

water from bare soil and somewhat greater transpiration from salt grass at field site 10. Dormant vegetation 

at field site 11 appears to have formed an insulating 

cover that shaded and reduced evaporation from the 

underlying soil during the spring and early summer. By 

July and August, the greater plant cover at field site 11 

is reflected in greater daily and monthly ground-water 

evapotranspiration (Nichols and others, 1997). 

Ground-water evapotranspiration at field site 10 once 

more exceeded that at field site 11 from October to the 

end of the year, again reflecting the shading of soil by 

dormant vegetation at field site 11. 

GROUND-WATER EVAPOTRANSPIRATION, PHREATOPHYTE PLANT COVER, AND DEPTH TO GROUND WATER A11 
o California data 

11 

0.8 

Q: 

~ 0.6 

a: 

w 

> 

0 

0 9 1-

z 

<( 0.4 .J 

Q. 

0.2 

•12 

0 LL~~~LL~~~LL~~~LL~~LLLL~~LL~~~LL~~~LL~~~LL~~~ 

.:... 

w 

w 

LL 

~ 

z 

0 

i= 

<( 

a: 

ii: 

en 

z 

<( 

a: 

1-

0 

Q. 

<( 

> w 

a: 

w 

1-

<( 

~ c 

z 

;:::) 

0 

a: 

C!J 

0 2 3 4 5 6 7 8 9 10 11 

DEPTH TO GROUND WATER, IN FEET 

Figure AS. Relation between plant cover and depth to ground water. Numbers refer to field sites 

shown on figure A 1 and described in table A 1 . 

2.5 

2.0 

Depth to ground 

water 

3 feet or less 

1.5 

Depth to ground 1.0 water 

1 0 feet or less 

0.5 

12 

0 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 

PLANT COVER (Cp) 

Figure A9. Annual ground-water evapotranspiration from phreatophyte shrubs and grasses and 

associated bare soil and the approximate depth to ground water. 

1.0 

A 12 Chapter A. Determining Ground-Water Evapotranspiration From Phreatophyte Shrubs and Grasses and From Bare Soil 
Winter (October through April) ground-water 

evapotranspiration is considered small to insignificant, 

and in areas where the depth to ground water is greater 

than 10 to 15ft, this is true. However, in areas where the 

depth to ground water is 3 ft or less, October to April 

ground-water evapotranspiration may be as much as 

0.6 ft and account for up to a quarter of the annual 

ground-water evapotranspiration. Most of this is evaporation from bare soil, because plants are dormant during much of this time. Some transpiration of ground 

water will occur, however, because phreatophyte 

shrubs remain green well into October and, on occasion, into November. During periods in the winter 

when soils near the surface are frozen, soil moisture 

and soil-water vapor derived from ground water 

continue to move toward the surface in response to soilwater tension gradients, and accumulate. When the frozen surface soils thaw, this ground water-derived soil 

moisture will be evapotranspired. 

SUMMARY AND CONCLUSIONS 

The equations presented here describe a functional relation: ( 1) between seasonal and annual 

ground-water evapotranspiration and plant cover, and 

(2) between seasonal and annual ground-water evapotranspiration and the depth to shallow ground water. 

They are an alternative to equations for estimating 

ground-water evapotranspiration by phreatophyte 

shrubs in the Great Basin proposed previously by 

Nichols (1994). These equations are not intended to be 

used to estimate ground-water evapotranspiration by 

saltcedar, willows, cottonwood trees, or other riparian 

vegetation. 

The proposed equations for estimating groundwater evapotranspiration as a function of plant cover 

are appropriate for estimating regional-scale groundwater evapotranspiration from remotely sensed vegetation index data, provided correlation can be made 

between plant cover used in this analysis and satellitedata-derived vegetation index. Equations that describe 

ground-water evapotranspiration as a function of the 

depth to ground water are appropriate for use in numerical models of ground-water flow and for other applications where the depth to ground water is known. 

REFERENCES CITED 

Arya, S.P., 1988, Introduction to micrometeorology: San 

Diego, Calif., Academic Press, International Geophysics Series, v. 42, 307 p. 

Blaney, H.F., Ewing, P.A., Israelson, O.W., Rohwer, C., and 

Scobey, F.C., 1938, Regional Planning, Part IV- The 

Rio Grande Joint Investigation in the upper Rio Grande 

Basin in Colo., N.Mex., and Tex., 1936-1937, Part IIIWater Utilization: United States Bureau of Agricultural 

Engineering Report, National Resources Committee, v. 

1' p. 293-427. 

Blaney, H.F., Taylor, C.A., and Young, A.A., 1930, Rainfall 

penetration and consumptive use of water in Santa Ana 

River Valley and coastal plain: California Department 

of Public Works, Water Resources Division Bulletin 33, 

162 p. 

Blaney, H.F., Taylor, C.A., Young, A.A., and Nickle, H.G., 

1933, Water losses under natural conditions in wet areas 

in southern California, Part I, Consumptive use by 

native plants growing in moist areas of southern California: California Department of Public Works, Water 

Resources Division Bulletin 44, p. 19-139. 

Businger, J.A., Miyake, M., Dyer, A.J., and Bradley, E.F., 

1967, On the direct determination of the turbulent heat 

flux near the ground: Journal of Applied Meteorology, 

v. 6, p. 1025-1032. 

Duell, L.F.W., Jr., 1990, Estimates of evapotranspiration in 

alkaline scrub and meadow communities of Owens Valley, California, using the Bowen-ratio, eddy-correlation, and Penman-Monteith methods: U.S. Geological 

Survey Water-Supply Paper 2370-E, 39 p. 

Gatewood, J.S., Robinson, T.W., Colby, B.R., Hem, J.D., and 

Halpenny, L.C., 1950, Use of water by bottom-land 

vegetation in lower Safford Valley, Arizona: U.S. Geological Survey Water-Supply Paper 1103, 210 p. 

Gay, L.W., and Fritschen, L.J., 1979, An energy balance budget analysis of water use by saltcedar: Water Resources 

Research, v. 15, p. 1589-1592. 

Groeneveld, D.P., and Warren, D.C., 1992, Total transpiration from land areas estimated from hand-held porometer measurements, in Wilson, D.H., Reginato, R.J., and 

Hollett, K.J., eds., Evapotranspiration measurements of 

native vegetation, Owens Valley, California, June 1986: 

U.S. Geological Survey Water-Resources Investigations Report 91-4159, p. 49-59. 

Harrill, J.R., Gates, J.S., and Thomas, J.M., 1988, Major 

ground-water flow systems in the Great Basin region of 

Nevada, Utah, and adjacent states: U.S. Geological Survey Hydrologic Investigations Atlas HA-694-C, 2 

sheets. 

Lee, C.H., 1912, An intensive study of the water resources of 

a part of the Owens Valley, California: U.S. Geological 

Survey Water-Supply Paper 294, 135 p. 

Malek, E., Bingham, G.B., and McCurdy, G.D., 1990, 

Evapotranspiration from the margin and moist playa of 

a closed desert valley: Journal of Hydrology, v. 120, 

p. 15-34. 

SUMMARY AND CONCLUSIONS A13 
Monteith, J.L., and Unsworth, M.H., 1990, Principles of 

~iwironmental physics (2d ed.): New York, Edward 

Arnold, 291 p. 

Mozingo, N.H., 1987, Shrubs ofthe Great Basin: Reno, University of Nevada Press, 342 p. 

Nichols, W.D., 1994, Groundwater discharge by phreatophyte shrubs in the Great Basin as related to depth to 

groundwater: Water Resources Research, v. 30, no.12, 

p. 3265-3274. 

Nichols, W.D., Laczniak, R.J., DeMeo, G.A., and Rapp, 

T.R., 1997, Estimated ground-water discharge by 

evapotranspiration, Ash Meadows area, Nye County, 

Nevada, 1994: U.S. Geological Survey WaterResources Investigation Report 97-4025, 13 p. 

Robinson, T.W., 1958, Phreatophytes: U.S. Geological Survey Water-Supply Paper 1423, 84 p. 

---1970, Evapotranspiration by woody phreatophytes in 

the Humboldt River valley near Winnemucca, Nevada: 

U.S. Geological Survey Professional Paper 491-D, 

41 p. 

Smith, J.L., Reece, B.D., and Medina, R.L., 2000, Data sets 

and related information for regional ground-water 

evapotranspiration in eastern Nevada: U.S. Geological 

Survey Open-File Report 99-242, CD-ROM. 

Tanner, C.B., 1960, Energy balance approach to evapotranspiration from crops: Soil Science Society of America 

Proceedings, 24, p. 1-9. 

Weeks, E.P., Weaver, H.L., Campbell, G.S., and Tanner, 

B.D., 1987, Water use by saltcedar and by replacement 

vegetation in the Pecos River floodplain between Acme 

and Artesia, New Mexico: U.S. Geological Survey Professional Paper 491-G, 33 p. 

White, W.N., 1932, A method of estimating ground-water 

supplies based on discharge by plants and evaporation 

from soil-Results of investigations in Escalante Valley, Utah, in Contributions to the hydrology of the 

United States 1932: U.S. Geological Survey WaterSupply Paper 659, p. 1-105. 

Young, A.A., and Blaney, H.F., 1942, Use of water by native 

vegetation: California Department of Public Works, 

Division of Water Resources Bulletin 50, 160 p. 

A 14 Chapter A. Determining Ground-Water Evapotranspiration From Phreatophyte Shrubs and Grasses and From Bare Soil 
Chapter B. Estimating Regional Ground-Water 

Evapotranspiration From Phreatophytes, 

Great Basin, Nevada 

By William D. Nichols, J. LaRue Smith, and Brian D. Reece 

Duckwater area 

Upper Fish Lake area Lockes area 

Bl 
Title-page photograph. Landsat Thematic Mapper color-infrared image, acquired August 13, 1985, of part of Nye County, 

Nevada. Bright red colors generally are broadleaf, healthy vegetation. Reddish brown colors generally are needle-leaf type 

vegetation. White colors are bare soil and low-density vegetation cover. Light to dark greenish colors are rangeland. Water is 

dark blue to black. Rectangles identify field-study areas discussed in this chapter. Yellow dash-and-dot lines are topographic 

boundaries between valleys. Map scale, about 10 miles per inch. 

Bll Chapter B. Estimating Regional Ground-Water Evapotranspiration From Phreatophytes, Great Basin, Nevada 
CONTENTS 

Abstract.................................................................................................................................................................................. B 1 

Introduction............................................................................................................................................................................ B 1 

Estimating Regional Ground-Water Evapotranspiration by Phreatophytes........................................................................... B3 

Ground-Water Evapotranspiration as a Function of Plant Cover .. . . ..... . . . ... . . . .... . . . ... .. . . .... . . . .... . . . .... . . . .. ... .. . . . . .............. ..... .. . . . . . B3 

Estimating Plant Cover at Regional Scales . .. .. . .. .. . . . .. .. . . .. . .. . . .. .. . . . . .. . . . . .. .. . . . .. . .. . .. .. . . . . .. .. . . . .. .. . . . .. .. .. . . . . . . .. .. .. . . . . . .. .. .. . .. . . . . . B4 

Corrections and Calibration of Landsat Data .. .. . . .. .. . . .. .. . . . .. . . . . . .. .. . . .. .. . . . . .. .. . . . .. .. . . .. .. .. . . . .. .. .. . . . . .. .. .. . .. . . . . . . .. .. .. . . . . B4 

Satellite Data and Vegetation Indices .. . . . ... . . . ..... . ..... . . .... . . . ... . . . ... .. . . ... .. . .. ... . . . ... . . . . .... . . . . ........... ............. ..... .. . . . . . B5 

Estimating Plant Cover From Vegetation Index Data..................................................................................... B5 

Estimating Regional Ground-Water Evapotranspiration............................................................................................ B6 

Summary and Conclusions . . . .... . . . .... . . . .. ... . . ..... . ..... . . .... . . .... . . ..... . . ..... . .... . . . .... . . . ... . . . .... . . . ..... . . . .... . . . ..... . . . .. .... . . . . ........... ............... B 10 

References Cited.................................................................................................................................................................... B 13 

FIGURES 

B 1. Map showing location of plant cover study areas, Great Basin, Nevada................................................................. B2 

B2. Graph showing correlation between modified soil-adjusted vegetation index, MSAVI, and plant cover, Cp. ......... B6 

B3-B5. Maps showing estimated phreatophyte plant cover, 1985, in: 

B3. Upper Fish Lake area, Little Fish Lake Valley, Nev.................................................................................... B8 

B4. Duckwater area, Railroad Valley, Nev. . . . .... . . . .... . . .... . . ..... . . . ..... . . ... . . . ..... . . ..... . . . ..... . . . .... .. . . . ..... . . . . . . . ..... . . . . . . ..... . B 11 

B5. Lockes area, Railroad Valley, Nev ............................................................................................................... B12 

TABLES 

B1-B2. Estimated ground-water evapotranspiration, 1985, from: 

B 1. Upper Fish Lake area, Little Fish Lake Valley, Nev. ................................................................................... B7 

B2. Duckwater springs and Lockes area springs, Railroad Valley, Nev............................................................. B9 

B3. Comparison of measured spring discharge and estimated evapotranspiration of spring discharge, 

Railroad Valley, Nev., 1985 .............................................................................................................................. B10 

CONTENTS Bill 
BIV Chapter B. Estimating Regional Ground-Water Evapotranspiration From Phreatophytes, Great Basin, Nevada 
Chapter B. Estimating Regional Ground-Water 

Evapotranspiration From Phreatophytes, 

Great Basin, Nevada 

By William D. Nichols, J. LaRue Smith, and Brian D. Reece 

ABSTRACT 

Previous ground-water studies estimated 

ground-water evapotranspiration by phreatophytes 

and bare soil in Nevada on the basis of results of 

field studies published in 1912 and 1932. More 

recent studies of evapotranspiration by rangeland 

phreatophytes, using micrometeorological methods as discussed in Chapter A of this report, 

provide new data on which to base estimates of 

ground-water evapotranspiration. An approach 

correlating ground-water evapotranspiration with 

plant cover is used in conjunction with a modified 

soil-adjusted vegetation index derived from Landsat data to develop a method for estimating the 

magnitude and distribution of ground-water 

evapotranspiration at a regional scale. Large areas 

of phreatophytes near Duckwater and Lockes in 

Railroad Valley are believed to subsist on ground 

water discharged from nearby regional springs. 

Ground-water evapotranspiration by the Duckwater phreatophytes of about 11,500 acre-feet estimated by the method described in this report compares well with measured discharge of about 

13,500 acre-feet from the springs near Duckwater. 

Measured discharge from springs near Lockes was 

about 2,400 acre-feet; estimated ground-water 

evapotranspiration using the proposed method was 

about 2,450 acre-feet. 

INTRODUCTION 

Evapotranspiration by phreatophyte shrubs 

and grasses and evaporation from bare soil are the principal mechanisms of ground-water discharge from the 

valleys of the Great Basin. Previous estimates of 

ground-water evapotranspiration by phreatophytes in 

Nevada were based on studies by Lee (1912) in Owens 

Valley, Calif.; White (1932) in the Escalante Desert, 

Utah; and, to a lesser extent, Robinson (1970) near 

Winnemucca, Nev. (fig. B 1). Estimates of groundwater evapotranspiration that were based on these studies have been used to estimate ground-water budgets 

for most of the valleys and hydrographic areas of 

Nevada (Rush, 1968). The estimated ground-water 

budgets, in tum, are used to allocate ground-water 

resources by the Nevada State Engineer. Any attempt 

to improve upon the estimated budgets requires an 

improvement of the data upon which the estimates 

were based, specifically estimates of ground-water 

evapotranspiration. 

Small, battery-powered data loggers and 

micrometeorological instruments suitable for completing energy budget evapotranspiration studies at remote 

locations became available in the early 1980's. The 

U.S. Geological Survey began a series of field studies 

in 1988 (Nichols, 1992, 1993, 1994; Nichols and Rapp, 

1996; Nichols and others, 1997) to measure groundwater evapotranspiration from phreatophytes typical to 

the Great Basin. These studies provided revised evapotranspiration rates and a better understanding of evapotranspiration processes from which ground-water 

evapotranspiration estimates could be reevaluated. 

Correlation between plant cover and ground-water 

evapotranspiration (as discussed in Chapter A of this 

report) provided equations from which to estimate 

regional ground-water evapotranspiration using Landsat data. 

This chapter describes a method for estimating 

regional ground-water evapotranspiration by phreatophyte shrubs and grasses and associated bare soil in the 

Great Basin as a function of plant cover determined 

from a vegetation index derived from Landsat data. 

ABSTRACT 81 
_.'t-]·~··1 

42° ...___R_l~A. =' -~ .. IoA~~ (" --;~ r;y:·j __ - ) 

l "'-=)"""'·) v ~ .. • Winnemucca . \ 

· .4.. ·. Salt Lake City • '- • Eiko \1' ( (Jr' Smoke c,eek Deo;ert 

. 

. 

. . 

~ . 

• Reno 

) 

• Carson City 

I 

Smith Creek 

Valley _r''· 

s· t ............ ,Ely 

L,/ Little Fish ; ·· ) < .-,j ~rea of 

Lake Valley . u-'· ~Igure 84 

Area of ld Jo: 

J ~ ( . 

~:\ ~ figure 83 ··Area of 

figure 85 · · /r. ( . Railroad Valley 

.. -----... .. r ' (northern part) 

~ 

.. \ ·J 

.. ./·· J \ 

t~', \ ' ~ \\ ' : 0 -}~ 

{ Owens ~<'«- ?to ~ ·.Valley 0~ ~ 

\ "'· ~-<1 ' J 

EXPLANATION \-.. 

• Ash Meadows 

Las Vegas • 

- • • - Boundary of Great Basin- Modified 

from Harrill and others (1988) 

- - - - Topographic valley boundary ~"' . , rv 

,......_ ........ ./ ·...._,_. ) 

Base from U.S. Geological Survey digital data, 1:100,000, 1978-88 

Universal Transverse Mercator Projection, Zone 11 

0 50 100 150 

~ (: :;; . 

' 1 / 

II J ,..-J: 

~·· 

. . 

I : 

v 

200 MILES 

ARIZONA 

0 50 100 150 200 KILOMETERS 

Figure 81 . Location of plant cover study areas, Great Basin, Nevada. 

B2 Chapter B. Estimating Regional Ground-Water Evapotranspiration From Phreatophytes, Great Basin, Nevada 
ESTIMATING REGIONAL GROUND-WATER 

EVAPOTRANSPIRATION BY 

PHREATOPHYTES 

The early studies of Lee (1912) and White (1932), 

and the somewhat later study of Robinson ( 1970), provided preliminary data for estimating ground-water 

evapotranspiration from saltgrass and phreatophyte 

shrubs in the Great Basin. The results of these studies, 

however, were difficult to apply and transfer to other 

areas because the studies did not correlate the estimated 

ground-water evapotranspiration with uniquely defining criteria, such as leaf area index. 

More recent studies (Carman, 1989; Duell, 1990; 

Malek and others, 1990; Nichols, 1992; 1993) using 

micrometeorological methods to measure evapotranspiration from rangeland phreatophytes also did not 

include information needed to transfer the site-specific 

results to areas with different vegetation and groundwater conditions. Transferability problems can in part 

be attributed to the difficulty of collecting evapotranspiration data at a sufficient number of rangeland locations and over a long enough time to begin addressing 

issues of similarity and variability of results among 

sites. 

A relation between ground-water evapotranspiration from phreatophytes and the depth to ground water 

has been assumed and, to some extent, demonstrated, 

but until recently only Lee (1912) had proposed equations to describe this relation for saltgrass. Using field 

measurements and the results of an energy-combination 

model to separate soil evaporation and plant transpiration, Nichols (1994) proposed a functional relation 

between phreatophyte-shrub ground-water transpiration and shrub density, shrub leaf area index, and the 

depth to ground water. Subsequently (Chapter A), the 

analysis was extended to develop a functional relation 

between plant cover and ground-water evapotranspiration from phreatophyte shrubs and saltgrass and associated baie soil. The following discussion summarizes 

that analysis, which is described in detail elsewhere 

(see Chapter A). 

GROUND-WATER EVAPOTRANSPIRATION 

AS A FUNCTION OF PLANT COVER 

Energy-budget studies of ground-water evapotranspiration from native rangeland were done in the 

Smoke Creek Desert, Smith Creek Valley, Railroad Valley, and the Ash Meadows area, Nev. (fig. B1; Nichols, 

1994; Nichols and others, 1997). Data from these sites 

and from seven sites in Owens Valley, Calif. (Duell, 

1990), were used to develop a correlation between 

ground-water evapotranspiration and plant cover. Site 

descriptions and data used in the analysis are given in 

Chapter A of this report. 

The analysis in Chapter A concluded that groundwater evapotranspiration from saltgrass/meadow grass, 

phreatophyte shrubs, and the associated bare soil could 

be estimated as a function of plant cover determined 

from plant density (d) and leaf area index (LA/). Chapter A discusses these two variables, and gives an equation that relates the two in terms of the shrub leaf area 

index (LA/p ), which is the leaf area per unit ground area 

for individual shrubs along a measured plant-density 

transect. The equations are 

LA/ = d(LA/p)max (1) 

and 

C =LA/ 

p 4 (2) 

where d, (LA/p )max, and Cp are defined in Chapter A. 

Measured evapotranspiration at each field site 

was corrected by subtracting precipitation that occurred 

during the measurement period. The resulting value for 

ground-water evapotranspiration includes evaporation 

of ground water from any bare soil at the field site, but 

does not include evaporation of soil moisture from 

recent precipitation. Least-squares analysis (Chapter A) 

indicated the curve that best described the data is an 

exponential equation of the form 

where ETis mean daily May-September, mean daily 

October-April, annual mean daily, or annual 

total ground-water evapotranspiration; 

Cp is plant cover; and 

a, b, and care coefficients for estimating seasonal and 

annual ground-water evapotranspiration. 

Values for the three coefficients and for r

2, the coefficient of determination for each time interval, are given 

in table A4. 

Seasonal and annual ground-water evapotranspiration estimated by these equations are difficult to compare with estimates from earlier studies (Lee, 1912; 

White, 1932; Robinson, 1970) because the earlier 

studies did not relate evapotranspiration rates to the leaf 

area index or to plant cover. Similarly, estimates that are 

ESTIMATING REGIONAL GROUND-WATER EVAPOTRANSPIRATION BY PHREATOPHYTES 83 
based on these equations cannot be compared directly 

to estimates reported by previous ground-water 

resources studies in Nevada because these earlier 

reports provided only a qualitative description of plant 

cover such as sparse, moderate, moderately dense, or 

dense. Estimates made with equation 3 and those made 

in previous studies can be compared only at the 

regional scale of previous estimates. 

Estimating Plant Cover at Regional Scales 

Satellite data have been used for several decades 

to describe land-surface cover in many ways. Many 

methods have been developed for characterizing vegetation using these data, especially data from Landsat 

satellites. Some methods, such as those using falsecolor IR (infrared) images, provide a qualitative measure of vegetation that readily distinguishes healthy 

from stressed vegetation. Land-cover classification 

methods commonly provide descriptive information on 

the type of land cover at increasing levels of detail. The 

level of detail for a multilevel land-cover classification 

of rangeland areas might be from rangeland at the first 

level to shrub and brushland at the second level to sagebrush prairies at the third level (Sabins, 1987). Finally, 

several indices have been determined over the years 

from Landsat data as a means of quantitatively describing vegetation. These indices provide regional plantcover information that is appropriate for use in the 

equations proposed by Nichols (see Chapter A). 

Corrections and Calibration of Landsat Data 

Landsat is an unmanned earth-orbiting satellite 

system, the first of which was launched in 1972. The 

satellite imagery used in this study was acquired by 

Landsat 5 launched in 1984. Landsat satellites are in a 

sun-synchronous orbit with the south-bound segment 

of the orbit during daylight and the north-bound segment at night. These satellites collect reflectance data 

continuously along orbital paths that are repeated every 

16 days. The data are used to create images that are 

subdivided into scenes that cover about 115 mi by 

115 mi on the land surface. The scenes consist of picture elements, or pixels, that have a resolution of about 

90 ft by 90 ft. 

Landsat includes a thematic mapper (TM) radiometer that measures visible radiation and reflected 

and thermal IR in seven wavelength bands ranging 

from 0.45 to 12.5 J.Lm (micrometers) and a multispectral scanner (MSS) radiometer that measures visible 

radiation and reflected IR in four wavelength bands 

ranging from 0.5 to 1.1 J.Lm. The Landsat data of interest for this study are in TM spectral bands 3 and 4, 

which include visible reflectance in the red wavelengths of 0.63- 0.69 J.Lm (band 3) and non-visible 

reflectance in the near-infrared (NIR) wavelengths 

of 0.76-0.90 J.Lm (band 4). Data in these wavelength 

bands are used to calculate different vegetation indices. 

More detailed descriptions of the Landsat satellites and 

the data collected by them can be obtained from Sabin 

( 1987) or other standard sources on remote sensing. 

The energy from the earth's surface measured by 

Landsat instruments is recorded as a digital number 

(DN) that ranges from 0 to 255. Variations in DN across 

a satellite image are caused primarily by variations in 

surface reflectance. However, the measured energy 

also is affected by such factors as scene illumination, 

atmospheric conditions, viewing geometry, and instrument response characteristics (Lillisand and Kiefer, 

1987). The TM data used for this study were acquired 

on June 10, 1985. An effort was made to obtain TM 

data during cloud-free days in late June when plant leaf 

area index was expected to be at a maximum. Reflectance values were corrected for the above effects so that 

any subsequent calculations using the vegetation indices would not be biased by factors unique to the June 

10, 1985, data. 

Corrections to the TM data for atmospheric 

effects were made using a method proposed by Chavez 

(1989). This technique provides for the selection of a 

relative atmospheric-scattering model and predicted 

haze values from the image data. Sensor and astronomical corrections also were applied. 

Calibration of TM data and conversion to percent 

reflectance using this technique makes several assumptions. The procedure converts the DN recorded by the 

radiometer to a radiance value by correcting for the 

gain and offset of the sensor. Top-of-the-atmosphere 

radiance values are then converted to ground reflectance values using the astronomical factors of sun 

angle, the distance between the earth and the sun at 

the time of data acquisition, and the exoatmospheric 

spectral irradiance. Atmospheric influences include 

haze and atmospheric attenuation. Atmospheric haze is 

solar radiation that is scattered by the atmosphere into 

the radiometer, and is an additive component of measured radiation. Atmospheric attenuation, a mutiplicative component, is the decrease in the intensity of 

reflected sunlight as it travels through the atmosphere. 

., 

B4 Chapter B. Estimating Regional Ground-Water Evapotranspiration From Phreatophytes, Great Basin, Nevada 
Attenuation is difficult to determine, and was not 

accounted for when making corrections to the data 

used in this study. Attenuation by large concentrations 

of water vapor in the atmosphere may affect the near 

infrared portion of the spectrum, but this effect is 

expected to be minimal in the semi-arid environment 

of Nevada. Atmospheric conditions may change over 

a region as large as that shown in a Landsat image or 

from valley to valley within a smaller region; however, 

it was assumed that the atmosphere was constant 

across the image. 

Satellite Data and Vegetation Indices 

Two of the most commonly used vegetation indices derived from Landsat data are the normalizeddifference vegetation index (NDVI), which is given by 

NDVI = PNIR- Pred , 

PNIR + Pred 

(4) 

and the perpendicular vegetation index (PVI), which is 

given by 

(5) 

where pis the reflectance in the near-infrared (NIR) or 

red bands, and 

a and~ are soil-line variables (Qi and others, 1994). 

The soil line is determined by the ratio of p NIR to 

p red for bare soil. A functionally equivalent form of the 

PVI is the weighted-difference vegetation index 

(WDVI), which is given by (Qi and others, 1994) 

WDVI = PNIR- 'YPred ' (6) 

where "{is the slope of the soil line. 

Studies summarized by Huete (1988) noted that 

these indices are influenced by soil background conditions in areas with partial and sparse plant canopy 

conditions. Huete (1988) proposed a soil-adjusted vegetation index to compensate for the influence of soil 

background effects. This index included a soil-adjustment factor that varied between 0 and 1, but was constant for all reflectance values. Qi and others (1994) 

proposed a modified soil-adjusted vegetation index 

(MSAVI) that included an automatically determined 

soil-adjustment factor that may differ for every pixel. 

The MSAVI is given by 

MSAVI = PNIR- Pred (1 + L) ' (7) 

PNIR + Pred + L 

where Lis the soil adjustment factor and is given by 

L = 1- 2y(NDVI)(WDVI) , (8) 

where "{is the slope of the soil line as in equation 6 and 

is equal to 1.06 (Qi and others, 1994). 

The MSAVI is the index used in the present study. 

Estimating Plant Cover From Vegetation Index 

Data 

Few data are available with which to correlate 

plant cover and MSAVI. Qi and others ( 1994, p. 124) 

present data for plant cover from 20 percent (Cp = 0.2) 

to about 97 percent (Cp=0.97) and indicate a linear 

relation between MSAVI and plant cover over this 

range. At plant covers less than about 15 percent (Cp = 

0.15), soil-noise influences become more significant 

despite the built-in soil-adjustment factor. However, 

these are the plant cover conditions that are most 

important throughout Nevada and the Great Basin 

where areas of sparse vegetation extend to hundreds of 

thousands of acres with annual ground-water evapotranspiration of tens to hundreds of thousands of acrefeet. 

Plant cover data were collected in Little Fish 

Lake and Railroad Valleys in 1995 (fig. B1). Landsat 

data for June 1995 were not available at the time the 

study was completed. Measured plant cover was correlated with MSAVI values derived from June 1985 Landsat data. Climatic conditions during 1984-85 were 

similar to those in 1994-95 and it was assumed that 

plant cover conditions also were similar. Subsequent 

analysis suggests plant cover may change by several 

percent from one year to the next (for example, from 

0.07 to 0.09 or from 0.15 to 0.12). This interannnual 

variability has not materially affected the correlation 

between field measurements and MSAVI determined by 

the present study. However, this assumption should be 

verified by additional analyses using contemporaneously collected field and satellite data. 

Measured plant cover (fig. B2) ranged from less 

than 5 to 20 percent ( Cp = 0.05 to 0.20), and fall within 

the lower end of the linear relation shown by Qi and 

others (1994, p. 124). Examination of MSAVI values 

for playas and other known areas of bare soil in the 

study area suggest that bare soil may exhibit MSAVI 

values of as much as 0.065 to 0.070. This is approximately the magnitude of the soil noise effect indicated 

by Qi and others (1994). From this, it was concluded 

that an MSAVI of 0.070 or less represented zero percent 

plant cover (Cp = 0.0). For MSAVI less than 0.16, 

GROUND-WATER EVAPOTRANSPIRATION AS A FUNCTION OF PLANT COVER 85 
1.0 .---------------------------;;r---, 

For MSAVI <0.16: Cp = 0.513 + 0.191 ln(MSAVI) / 

For MSA VI =>0.16: Cp = -0.0177 + 1.1308(MSA VI) / 

/ 

/ 

/ 0.8 .a. Field measurement 

/ 

/ 

/ Q: 

~ 

a: 

w 

> 0 

0 

0.6 

/ / / ~ From Qi and others (1994) 

/ .... 

z 

<C 

...J 

0.. 

0.4 

0 

/ 

/ 

0.2 

/ 

/ 

0.4 0.6 0.8 1.0 

MODIFIED SOIL-ADJUSTED VEGETATION INDEX, (MSAVI) 

Figure 82. Correlation between modified soil-adjusted vegetation index, MSAVI, and plant 

cover, Cp. 

the relation between MSAVI and plant cover was determined to be best described by a logarithmic equation 

(~ = 0.84) 

Cp = 0.5130 + 0.1910ln(MSA VI) . (9) 

For MSAVI equal to or greater than 0.16, the 

approximate relation shown by Qi and others ( 1994) 

was used (fig. B2). This relation was determined from 

the value of Cp given by equation 9 for MSAVI = 0.16 

and the value of MSAVI (about 0.90) for Cp = 1.0 of the 

relation shown by Qi and others (1994, p. 124). The linear equation determined from these values is 

Cp = -0.0177 + 1.1308(MSAV/) . (10) 

Estimating Regional Ground-Water 

Evapotranspiration 

Data from the Landsat scene covering the area of 

interest were geocorrected and corrected for atmospheric effects. NDVI, WDVI, and MSAVI were calculated for each pixel of the scene using equations 4, 6, 7, 

and 8. MSAVI values were converted to plant cover 

values with equations 9 and 10. Plant cover values for 

individual pixels were assigned to plant-cover zones 

corresponding to bare soil, less than 10 percent cover, 

10 to less than 20, 20 to less than 35, 35 to less than 50, 

and 50 percent and greater. Each zone was assigned a 

color used to display the plant cover distribution on the 

Landsat scene image. 

The resulting plant-cover distribution applies to 

vegetation over the entire Landsat scene. To restrict an 

analysis only to phreatophyte areas, it is necessary to 

define the boundaries of phreatophytes in the area of 

interest. Field mapping of phreatophyte area boundaries for this study was done on U.S. Geological Survey 1:24,000 topographic quadrangle maps. The outer 

boundary of the phreatophyte area was assumed to represent the limit beyond which the depth to ground 

water was too great for phreatophytes to grow and 

within which the depth to ground water was sufficiently shallow that any plants growing there were 

using ground water. The field-verified phreatophyte 

boundary was transferred to the Landsat image of the 

study area to define the area for which ground-water 

evapotranspiration was calculated from plant cover. 

MSAVI, Cp, and ground-water evapotranspiration were 

calculated for each pixel, an area of 8, 7 43 ft2 or about 

0.20 acre, of the Landsat scene inside the phreatophyte 

boundary area. The volume of ground-water evapotranspiration and the area for each plant-cover zone 

were determined by summing the results within each 

zone. 

Typical results are shown in figure B3 and 

given in table B 1 for the Upper Fish Lake quadrangle 

in Little Fish Lake Valley (fig. B1). About 2,600 acres 

B6 Chapter B. Estimating Regional Ground-Water Evapotranspiration From Phreatophytes, Great Basin, Nevada 
of the quadrangle are covered by phreatophyte shrubs 

and grasses. Phreatophyte plant cover in the quadrangle 

in 1985 ranged from an average of about 8 percent ( Cp 

= 0.08) in the less than 10 percent zone to an average of 

about 60 percent (Cp = 0.60) in the greater than 50 percent zone, although coverage for individual pixels 

ranged from no plant cover (bare soil) to as much as 

75 percent (Cp = 0.75) cover. Estimated ground-water 

evapotranspiration by phreatophytes was about 4,000 

acre-ft. 

The total water area of Little Fish Lake and Upper 

Fish Lake in Fish Lake Valley was about 800 acres in 

June 1985 (Chapter C of this report). Of this, 537 acres 

of surface water were within the limits of the Upper 

Fish Lake quadrangle-462 acres of Upper Fish Lake 

and 75 acres of Little Fish Lake. Upper Fish Lake commonly contains no water, but 1985 followed several 

years of above-normal precipitation. Little Fish Lake is 

a perennial lake, one of the few in the area, but most of 

the lake is south of the Upper Fish Lake quadrangle. Its 

total size ranged from 269 acres in 1985 to 187 acres in 

1989 (Chapter C). Open-water evaporation in this area 

of Nevada may be as much as 4.5 ft/yr (Scott, 1971), 

but for Little Fish Lake it is not known how much of 

this represents ground water. It has been estimated that 

about 500 acre-ftlyr of ground water is evaporated from 

all of Little Fish Lake (Chapter C). Perhaps as much as 

100 acre-ft of ground water was evaporated in 1985 

from that part of Little Fish Lake within the limits of 

the Upper Fish Lake quadrangle. 

Few ways are available by which to corroborate 

ground-water evapotranspiration estimated by the 

method described in this report. One way is to use this 

method to estimate evapotranspiration from areas near 

large springs and compare the estimated evapotranspiration to measured spring discharge. Large regional 

springs exist at Duckwater (fig. B4) and near Lockes 

(fig. B5) in Railroad Valley. Discharge from these 

springs appear to support large areas of phreatophyte 

shrubs and grasses. All or most of the measured discharge from these springs is assumed to be consumed 

by evapotranspiration by these phreatophytes. Discharge from the springs was measured periodically 

from 1968 to 1972 and from 1982 to 1988. 

The areas near Duckwater and Lockes in which 

plant cover is affected by measured discharge from the 

springs can be delineated reasonably well on the plant 

cover map (figs. B4 and B5) derived from the Landsat 

image on the basis of plant cover, topography, and 

spring location. Estimated ground-water evapotranspiration from the Duckwater area (fig. B4) and for the 

area estimated to represent evapotranspiration of measured spring discharge are given in table B2. Groundwater evapotranspiration from the area west of the 

spring discharge area near Duckwater (fig. B4) may be 

associated with shallow ground water related to the 

nearby regional springs, but would not be supported by 

any of the measured discharge from those springs and 

is not included in the area believed to be affected by 

measured spring discharge. Estimated ground-water 

evapotranspiration of about 11,500 acre-ft is assumed 

to represent spring discharge at Duckwater and is comTable 81. Estimated ground-water evapotranspiration from the Upper Fish Lake area, 

Little Fish Lake Valley, Nevada, 1985 1 

[Symbol: --, no data; E, estimated.] 

Average Area 

Evapotranspiration 

plant cover (acres) Annual average Summer Winter Annual 

rate (feet) (acre-feet) (acre-feet) (acre-feet) 

Open water 0 537 E 

Playa/bare soil 0 26 0.150 

Cover <10 percent .084 319 .632 142 59 

Cover 10 to <20 percent .145 1,510 1.401 1,534 582 

Cover 20 to <35 percent .258 530 2.148 850 288 

Cover 35 to <50 percent .418 132 2.504 253 78 

Cover >50 percent .600 89 2.588 179 51 

Total 3,143 2,958 1,058 

1 Calculated values are not rounded, to minimize rounding errors in the subsequent calculations, except as indicated. 

2 Rounded to nearest 100 acre-feet. 

lOOE 

4 

201 

2,116 

1,138 

331 

230 

2

4,100 

GROUND-WATER EVAPOTRANSPIRATION AS A FUNCTION OF PLANT COVER 87 
116°30' 

38°37'30" .--------------~~...-----------------. 

3 MILES 

I 

Little Fish 

Lake 

I 

3 KILOMETERS 

Base from U.S. Geological Survey digital data, 1:100,000, 1978 

Universal Transverse Mercator projection 

Zone 11 

EXPLANATION 

Land cover within phreatophyte areaGround-water evapotranspiration for indicated plant cover is given in table 81 

c=J Water (1985) 

D Playa I Bare soil 

~ Less than 10 percent phreatophyte plant cover, mostly shrubs but may 

include sparse saltgrass 

10 to less than 20 percent phreatophyte plant cover, dominately shrubs 

but may include sparse saltgrass 

D 20 to less than 35 percent phreatophyte plant cover, mixed shrubs and 

grasses 

D 35 to less than 50 percent phreatophyte plant cover, dominantly grasses 

but may include scattered shrubs 

50 percent and greater phreatophyte plant cover, dominantly grasses 

with sedges and rushes in areas of shallow ground water 

Figure 83. Estimated phreatophyte plant cover in Upper Fish Lake area, Little Fish 

Lake Valley, Nevada, 1985. 

B8 Chapter B. Estimating Regional Ground-Water Evapotranspiration From Phreatophytes, Great Basin, Nevada 
Table 82. Estimated ground-water evapotranspiration from the Duckwater Springs and Lockes area springs, Railroad 

Valley, Nevada, 1985 1 

[Symbol: --, no data; E, estimated] 

Average 

Evapotranspiration 

Area 

plant cover (acres) Annual average Summer Winter Annual 

rate (feet) (acre-feet) (acre-feet) (acre-feet) 

Railroad Valley - Duckwater area 

Open water 1 3E 

Playa/bare soil 40 0.150 6 

Cover < 10 percent 0.064 3,837 .383 1,032 436 1,468 

Cover 10 to <20 percent .139 1,346 1.336 1,301 497 1,798 

Cover 20 to <35 percent .277 1,004 2.215 1,667 557 2,224 

Cover 35 to <50 percent .424 927 2.511 1,781 545 2,326 

Cover >50 percent .706 1,785 2.580 3,609 995 4,604 

Total 8,940 9,390 3,030 2 12,500 

Railroad Valley - Duckwater Springs 

Open water 1 3E 

Playa/bare soil 23 .150 3 

Cover <10 percent .073 1,574 .497 551 231 782 

Cover 10 to <20 percent .141 1,176 1.350 1,149 438 1,587 

Cover 20 to <35 percent .277 994 2.216 1,651 552 2,203 

Cover 35 to <50 percent .424 923 2.511 1,774 543 2,317 

Cover >50 percent .707 1,779 2.580 3,598 992 4,590 

Total 6,470 8,723 2,756 211,500 

Railroad Valley - Lockes area 

Open water 50 150E 

Playa/bare soil 21,602 .150 3,240 

Cover <10 percent .042 13,180 .189 1,748 748 2,496 

Cover 10 to <20 percent .136 1,668 1.303 1,571 603 2,174 

Cover 20 to <35 percent .259 394 2.152 634 215 849 

Cover 35 to <50 percent .398 70 2.483 132 41 173 

Cover >50 percent .543 12 2.582 25 7 32 

Total 36,976 4,110 1,614 2

9,100 

Railroad Valley - Lockes area springs 

Open water 21 63 E 

Playa/bare soil 315 .150 47 

Cover < 10 percent .061 1,467 .380 392 165 557 

Cover 10 to <20 percent .140 758 1.344 738 281 1,019 

Cover 20 to <35 percent .262 302 2.164 488 165 653 

Cover 35 to <50 percent .397 62 2.482 117 36 153 

Cover >50 percent .545 10 2.583 20 6 26 

Total 2,935 1,755 653 22,500 

1 Calculated values are not rounded, to minimize rounding errors in subsequent calculations, except as indicated. 

2 Numbers are rounded to the nearest 100 acre-ft for values less than 10,000 acre-ft and to the nearest 500 acre-ft for values greater than 

10,000 acre-ft. 

GROUND-WATER EVAPOTRANSPIRATION AS A FUNCTION OF PLANT COVER 89 
pared with measured spring discharge of about 13,500 

acre-ft in table B3. Estimated ground-water evapotranspiration is somewhat less than the measured 

spring discharge, but given the large area influenced by 

this spring discharge it is possible that the delineated 

area shown on figure B4 is in error or that some of the 

measured spring discharge infiltrates back into the 

shallow ground-water system and moves beyond the 

local phreatophyte area before it is evapotranspired by 

phreatophytes within the phyreatophyte boundary. 

Additionally, the measurements of spring discharge 

may be in error by 5 to 15 percent. The reason for the 

discrepancy is probably a combination of all these 

sources of error. 

Estimated ground-water evapotranspiration from 

the Lockes area and from the area influenced by measured spring discharge near Lockes (fig. B5) also are 

given in table B2. Substantial areas of phreatophytes 

occur in the Lockes area (fig. B5) and are probably supported by the shallow ground water associated with the 

springs in the area. The area believed to be influenced 

by measured discharge from the springs near Lockes is 

shown in figure B5. The estimated ground-water 

evapotranspiration of about 2,500 acre-ft from this area 

is within the range of spring discharge of about 2,400 

acre-ft measured in 1985 and 1986. The same possible 

sources of error in the estimated evapotranspiration and 

measured spring discharge described for the Duckwater area apply to the estimates and measurements for 

the Lockes area as well. 

The good comparison between measured spring 

discharge and estimated ground-water evapotranspiration from the spring discharge areas at Duckwater and 

near Lockes suggests that the estimates of regional 

ground-water evapotranspiration, which are based on 

plant cover derived from Landsat MSAVI data, are reasonable. 

SUMMARY AND CONCLUSIONS 

The method of estimating ground-water discharge by evapotranspiration from phreatophytes for 

ground-water studies conducted in Nevada from the 

mid-1940's to the present used the results of field studies published in 1912 and 1932. Ground-water budgets 

based on these discharge estimates are used to allocate 

ground-water resources in Nevada. The results of more 

recent studies of evapotranspiration by rangeland 

phreatophytes using micrometeorological methods 

provide new data on which to base estimates of groundwater evapotranspiration. 

An approach correlating ground-water evapotranspiration with plant cover was used in conjunction 

with a modified soil-adjusted vegetation index derived 

from Landsat data to develop a method for estimating 

the magnitude and distribution of ground-water evapotranspiration at a regional scale. Ground-water evapotranspiration was estimated using this method for two 

areas in Railroad Valley in which all or most of measured spring discharge is assumed to be consumed by 

evapotranspiration. Ground-water evapotranspiration 

of about 11,500 acre-ft/yr estimated by the method 

described herein compares well with measured discharge of about 13,500 acre-ft/yr from regional springs 

at Duckwater. Measured discharge from springs near 

Table 83. Comparison of measured spring discharge and estimated evapotranspiration of spring 

discharge, Railroad Valley, Nevada, 1985 1 

[Values of discharge and evapotranspiration in acre-feet per year] 

Date of Spring Date of Spring Estimated 

Spring location evapotranspiration, measurement discharge measurement discharge this study 

Duckwater 2 1-19-1985 14,000 2-3-1986 13,000 11,500 

Lockes 3 1-20-1985 2,500 2-2-1986 2,300 2,500 

1 Numbers are rounded to the nearest 100 acre-ft for values less than 10,000 acre-ft and to the nearest 500 acre-ft for values 

greater than 10,000 acre-ft. 

2 Includes discharge from Big Warm Spring and Little Warm Spring (Savard and Crompton, 1993, p. 78). 

3 Includes discharge from Hay Corral, North, Big, and Reynolds springs (Savard and Crompton, 1993, p. 77-78). 

B10 Chapter B. Estimating Regional Ground-Water Evapotranspiration From Phreatophytes, Great Basin, Nevada 
115°45' 

39 00 .---------------------------------------------------------------------------------------------~ 

0 

I I 

0 3 KILOMETERS 

Base from U.S. Geological Survey digital data, 1 :100,000, 1980 

Universal Transverse Mercator projection 

Zone 11 

3 MILES 

I 

EXPLANATION 

Land cover within phreatophyte areaGround-water evapotranspiration for indicated 

plant cover is given in table B2 

D 

D 

Playa I Bare soil 

Less than 10 percent phreatophyte plant 

cover, mostly shrubs but may include 

sparse saltgrass 

10 to less than 20 percent phreatophyte 

plant cover, dominately shrubs but may 

include sparse saltgrass 

20 to less than 35 percent phreatophyte 

plant cover, mixed shrubs and grasses 

35 to less than 50 percent phreatophyte 

plant cover, dominantly grasses but may 

include scattered shrubs 

50 percent and greater phreatophyte plant 

cover, dominantly grasses with sedges 

and rushes in areas of shallow ground 

water 

Approximate boundary of area of 

phreatophytes supported by spring 

discharge 

Figure 84. Estimated phreatophyte plant cover in the Duckwater area, Railroad Valley, Nevada, 1985. 

SUMMARY AND CONCLUSIONS 811 
0 3 MILES 

I I I 

0 3 KILOMETERS 

Base from U.S. Geological Survey digital data, 1 :100,000, 1980 

Universal Transverse Mercator projection 

Zone 11 

EXPLANATION 

Land cover within phreatophyte area-Ground-water evapotranspiration for 

indicated plant cover is given in table 82 

D 

D 

-

Water 

Playa I Bare soil 

Less than 10 percent phreatophyte plant 

cover, mostly shrubs but may include 

sparse saltgrass 

10 to less than 20 percent phreatophyte 

plant cover, dominately shrubs but may 

include sparse saltgrass 

20 to less than 35 percent phreatophyte 

plant cover, mixed shrubs and grasses 

35 to less than 50 percent phreatophyte 

plant cover, dominantly grasses but may 

include scattered shrubs 

50 percent and greater phreatophyte plant 

cover, dominantly grasses with sedges 

and rushes in areas of shallow ground 

water 

Approximate boundary of area of phreatophytes supported by spring discharge 

Figure 85. Estimated phreatophyte plant cover in the Lockes area, Railroad Valley, Nevada, 1985. 

B12 Chapter B. Estimating Regional Ground-Water Evapotranspiration From Phreatophytes, Great Basin, Nevada 
Lockes was about 2,400 acre-ft/yr; estimated groundwater evapotranspiration using the proposed method 

was about 2,500 acre-ft/yr. 

REFERENCES CITED 

Carman, R.L., 1989, Measurement of evapotranspiration in 

phreatophyte areas, Smith Creek Valley and Carson 

Desert, west-central Nevada, 1983: U.S. Geological 

Survey Water-Resources Investigation Report 89-4118, 

18 p. 

Chavez, P.S., 1989, Radiometric calibration of Landsat Thematic Mapper multispectral images: Photogrammetric 

Engineering and Remote Sensing, v. 55, no. 9, p. 1285-

1294. 

Duell, L.F.W., Jr., 1990, Estimates of evapotranspiration in 

alkaline scrub and meadow communities of Owens Valley, California, using the Bowen-ratio, eddy-correlation, and Penman-combination methods: U.S. 

Geological Survey Water-Supply Paper 2370-E, 39 p. 

Groeneveld, D.P., and Warren, D.C., 1992, Total transpiration from land areas estimated from hand-held porometer measurements, Chapter E, in Wilson, D.H., 

Reginato, R.J., and Hollett, K.J., eds., Evapotranspiration measurements of native vegetation, Owens Valley, 

California, June 1986: U.S. Geological Survey WaterResources Investigations Report 91-4159, p. 49-59. 

Harrill, J.R., Gates, J.S., and Thomas, J.M., 1988, Major 

ground-water flow systems in the Great Basin region 

of Nevada, Utah, and adjacent states: U.S. Geological 

Survey Hydrologic Investigations Atlas HA-694-C, 

2 sheets. 

Huete, A.R., 1988, A soil-adjusted vegetation index (SAVI): 

Remote Sensing of Environment, v. 25, p 295-308. 

Lee, C.H., 1912, An intensive study of the water resources of 

a part of Owens Valley, California: U.S. Geological 

Survey Water-Supply Paper 294, 135 p. 

Lillesand, T.M., and Kiefer, R.W., 1987, Remote sensing and 

image interpretation: New York, John Wiley, 721 p. 

Malek, E., Bingham, G.B., and McCurdy, G.D., 1990, 

Evapotranspiration from the margin and moist playa 

of a closed desert valley: Journal of Hydrology, v. 120, 

p. 15-34. 

Monteith, J.L., and Unsworth, M.H., 1990, Principles of 

environmental physics (2d ed.): New York, Edward 

Arnold, 291 p. 

Nichols, W.D., 1992, The uncertainty of water budget estimates in the Great Basin, in Hermann, R., ed., Managing water resources during global change: American 

Water Resources Association 28th Annual Conference 

and Symposium, Reno, Nev., Nov. 1-5, 1992, p. 309-

317. 

---1993, Estimating discharge of shallow groundwater 

by transpiration from greasewood in the northern Great 

Basin: Water Resources Research, v. 29, no. 8, p. 2771-

2778. 

---1994, Groundwater discharge by phreatophyte 

shrubs in the Great Basin as related to the depth to 

groundwater: Water Resources Research, v. 30, no. 12, 

p. 3265-3274. 

Nichols, W.D., Laczniak, R.J., DeMeo, G.A., and Rapp, 

T.R., 1997, Estimated ground-water discharge by 

evapotranspiration, Ash Meadows area, Nye County, 

Nevada, 1994: U.S. Geological Survey WaterResources Investigations Report 97-4025, 13 p. 

Nichols, W.D., and Rapp, T.J., 1996, Micrometeorological 

data for energy budget and climate studies near Rogers 

Spring, Ash Meadows National Wildlife Refuge, Nye 

County, Nevada: U.S. Geological Survey Open-File 

Report 96-170, 49 p. 

Qi, J., Chehbouni, A., Huete, A.R., Kerr, Y.H., and 

Sorooshian, S., 1994, A modified soil adjusted vegetation index: Remote Sensing of Environment, v. 48, 

p. 119-126. 

Robinson, T.W., 1970, Evapotranspiration by woody 

phreatophytes in the Humboldt River valley near Winnemucca, Nevada: U.S. Geological Survey Professional Paper 491-D, 41 p. 

Rush, F.E., 1968, Index of hydrographic areas: Nevada Division of Water Resources, Information Series Report 6, 

38 p. 

Sabins, F.F., Jr., 1987, Remote sensing principles and interpretation (2d ed.): New York, W.H. Freeman and Co., 

449 p. 

Savard, C.S., and Crompton, E.J., 1993, Hydrologic data for 

east-central Nevada, water years 1982-88: U.S. Geological Survey Open-File Report 90-153, 128 p. 

Scott, B.R., 1971, Average annual evaporation: Nevada 

Division of Water Resources Map, scale 1:2,000,000. 

White, W.N., 1932, A method of estimating ground-water 

supplies based on discharge by plants and evaporation 

from soil- results of investigations in Escalante Valley, 

Utah, in Contributions to the hydrology of the United 

States 1932: U.S. Geological Survey Water-Supply 

Paper 659, p. 1-105. 

REFERENCES CITED 813 

Chapter C. Regional Ground-Water Budgets and 

Ground-Water Flow, Eastern Nevada 

ByWilliam D. Nichols 

Cl 
Title-page photograph. Quinn Canyon Range (right two-thirds of photo) and Southern Grant Range (left one-third of photo), 

Railroad Valley, Nevada, June 1994. View south from about 3 miles south of Lockes. Cliff-forming limestones of Cambrian 

. Windfall Formation and Ordovician Lower Pogonip Group are exposed near summit of high peaks of northern Quinn Canyon 

Range (left of center) ahd near top of more distant ridge of southern Grant Range (left center). Scattered vegetation in 

foreground is phreatophytic greasewood. Valley-wide evapotranspiration of ground water may total about 85,000 acre-feet per 

year for Railroad Valley, of which almost 30 percent may be supplied by interbasin ground-water flow from adjacent valleys. 

Photograph by William D. Nichols, U.S. Geological Survey. 

Cll Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
CONTENTS 

Abstract ......................................... ,: .................................................................................................................................... ~.. C1 

Introduction ...................................... ~·-............................................................................................................................. ~......... C 1 

Purpose and Scope ............ ;·· ............................................................................................................ .': .............. ~........... C2 

Study Area ......................... _:-: .................................................................................................................................... :.. C2 

Geography and Topography . . ....... .. ...... .......... ........ ........... ... . . . ... ... . ..... ........... .......... ... . . . . . . . . . . ............ ......... ... . C4 

Hydrogeology ·········:·•:...................................................................................................................................... C5 

Climate .................... ·.' .... :.................................................................................................................................. C5 

Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C7 

Previous Ground-Water Studies . . . ... . . . . . ....... .................. ... . . . . .......... .... .... .... ........ .......... .......... ........... .. ............. ... . . . . . . . C8 

Ground-Water Discharge Studies . . . . . . . . .... .. . . ...... ....... ........... ... . . . . . ... . . . . . .... .......... ... . . . . . ............... ............ .......... C9 

Recharge Studies . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C 10 

Reconnaissance Ground-Water Studies.......................................................................................................... C 11 

Estimated Ground-Water Discharge. and Recharge .. .. . .... ......... ......... .......... ... .......... ... . . . .......... ........... ............... .. .. . . . . . . . . ... . . . . C 12 

Discharge by Evapotranspiration ... : ........................................................................................................................... C12 

Evapotranspiration Rates in 1985 and 1989 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C 13 

Estimated Mean Annual Ground-Water Evapotranspiration .......................................................................... Cl5 

Recharge From Precipitation ...................................................................................................................................... C17 

Regional Precipitation .................................................................................................................................... C18 

Determination of Recharge Coefficients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C 19 

Estimated Recharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C24 

Estimated Ground-Water Budgets and Regional Flow .......................................................................................................... C24 

Newark Valley System .............................................................................................................................. .- ....... ~········· C26 

Railroad Valley System ................................................. ·............................................................................................. C27 

Independence Valley System .................................................................................................................................... ;~ C29 

Ruby Valley System ............ : .................................................. : ................................................................................... _ C31 

Colorado System........................................................................................................................................................ C32 

Goshute Valley System ........ : ............................................................................ _ ......................................................... C33 

Great Salt Lake Desert Systefu ................................ : ................................................................................................. C33 

Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C34 

References Cited.................................................................................................................................................................... C37 

PLATES 

[Plates in pocket at back of report.] 

1-4. Maps showing: 

1. Geographic, topographic, and cultural features of valleys in eastern Nevada study area 

2. Distribution of phreatophyte plant cover in 1985 and generalized bedrock geology of eastern Nevada study area 

3. Distribution of phreatophyte plant cover in 1989-and generalized bedrock geology of eastern Nevada study area 

4. Regional ground-water budgets and ground-water flow for valleys in eastern Nevada study area 

FIGURES 

Cl. Index map showing Great Basin and eastern Nevada study area.............................................................................. C3 

C2. Chart showing correlation of stratigraphic and hydrostratigraphic units in southern Nevada and the 

eastern Nevada study area..................................................................................................................................... C6 

C3-C4. Graphs showing: 

C3. Distribution of plant cover in Goshute Valley, 1985 and 1989 ...................................................................... C14 

C4. Precipitation-altitude relation, eastern Nevada .............................................................................................. C19 

C5. Map showing directions, locations, and estimated magnitude of interbasin ground-water flow in eastern Nevada 

as suggested by earlier studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C22 

CONTENTS Clll 
TABLES-~ 

Cl. Names and areas of valleys included in eastern Nevada study area........................................................................... C4 

C2. Climatic data for 1961-90 at selected valley locations in eastern Nevada................................................................. C7 

C3. Previous reconnaissance-level ground-water resources investigations for valleys in eastern Nevada study area ...... C11 

C4. Mean annual and annual precipitation for selected stations and time periods, eastern Nevada ................................. C13 

C5. Estimated ground-water evapotranspiration from phreatophytes, bare soil, and open water, eastern Nevada 

.. study area, for 1985, 1989, and mean annual conditions ....................................................................................... C15 

C6. Summary of area, percent plant cover, mean annual ground-water evapotranspiration rate, and annual 

evapotranspiration for indicated land cover for 1985 and 1989 for eastern Nevada study area ............................ C16 

C7. Coinparison of estimated mean annual ground-water evapotranspiration for eastern Nevada study area, 

from reconnaissance studies and from this study ................................................................................................... C18 

C8. Precipitation at selected SNOTEL stations in eastern Nevada, 1961-90 .................................................................... Cl9 

C9. Area and annual volume of precipitation estimated by reconnaissance studies and by present study for valleys 

in· eastern Nevada study area .................................................................................................................................. C20 

C10. Co.!nparison of area, average annual rate and annual volume of precipitation greater than 20 inches estimated 

py reconnaissance studies and equal to or greater than 20 inches estimated by the present study for valleys 

.ih eastern Nevada study area .................................................................................................................................. C20 

C11. Estimated ground-water evapotranspiration and interbasin ground-water flow for estimating ground-water 

t~charge for valleys in eastern Nevada study area .. . . . .......... ... . . . . . ....... ............ ..... ............. ................. ........... .... ..... C23 

C12. Coefficients for estimating recharge from precipitation in eastern Nevada study area .............................................. C24 

C13. An,nual ground-water recharge from precipitation estimated by reconnaissance studies and by present study 

for valleys of eastern Nevada study area ................................................................................................................ C25 

C 14. Estimated distribution of interbasin ground-water flow for valleys in eastern Nevada study area............................ C28 

C15. Smpmary of estimated ground-water budgets for valleys in eastern Nevada study area ........................................... C29 

C16. Summary of estimated ground-water budgets for regional flow systems in eastern Nevada study area and 

for overall study area .............................................................................................................................................. C35 

C17. Estimated ground-water discharge by-evapotranspiration from valleys in eastern Nevada study area, 

1985and1989 ........................................................................................................................................................ C41 

C18. Area and annual volume of precipitation in valleys of eastern Nevada study area .................................................... C45 

.C 19. Precipitation areas and volumes for selected precipitation zones and estimated recharge in valleys of 

eastern Nevada study area...................................................................................................................................... C53 

CIV Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
Chapter C. Regional Ground-Water Budgets and 

Ground-Water Flow, Eastern Nevada 

By William D. Nichols 

ABSTRACT 

Previous estimates of ground-water budgets 

in Nevada were based on methods and data that 

now are more than 60 years old. Newer methods, 

data, and technologies were used in the present 

study to estimate ground-water recharge from precipitation and ground-water discharge by evapotranspiration by phreatophytes for 16 contiguous 

valleys in eastern Nevada. Annual ground-water 

recharge to these valleys was estimated to be about 

855,000 acre-feet and annual ground-water evapotranspiration was estimated to be about 790,000 

acre-feet; both are a little more than two times 

greater than previous estimates. The imbalance of 

recharge over evapotranspiration represents 

recharge that either (1) leaves the area as interbasin flow or (2) is derived from precipitation that 

falls on terrain within the topographic boundary of 

the study area but contributes to discharge from 

hydrologic systems that lie outside these topographic limits. 

A vegetation index derived from Landsatsatellite data was used to estimate phreatophyte 

plant cover on the floors of the 16 valleys. The 

estimated phreatophyte plant cover then was used 

to estimate annual ground-water evapotranspiration. Detailed estimates of summer, winter, and 

annual ground-water evapotranspiration for areas 

with different ranges of phreatophyte plant cover 

were prepared for each valley. The estimated 

ground-water discharge from 15 valleys, combined with independent estimates of interbasin 

ground-water flow into or from a valley, were used 

to calculate the percentage of recharge derived 

from precipitation within the topographic boundary of each valley. These percentages then were 

used to estimate ground-water recharge from precipitation within each valley. 

Ground-water budgets for all16 valleys 

were based on the estimated recharge from precipitation and estimated evapotranspiration. Any 

imbalance between estimated recharge and estimated discharge may arise fro~ errors in estimated ground-water evapotranspiration, from 

errors in the estimated precipitation in the topographic basin, or, more likely from a combination 

of errors in the two estimates. Imbalance between 

recharge and discharge in any valley was corrected 

by assuming the difference was equal to interbasin 

ground-water flow into or out of the valley. The 

proposed interbasin flow includes all errors in estimated ground-water evapotranspiration and 

recharge. Estimates of interbasin flow were available from previous studies for most valleys. For 

some valleys, the present study is the first to propose the interbasin flow or to propose an increase 

in the quantity of interbasin flow. Proposed areas 

of interbasin flow are consistent with available 

geologic, geophysical, and hydrologic evidence, 

but the suggested interbasin flow is not substantiated by such evidence. 

INTRODUCTION 

Ground-water resources in Nevada are managed 

on the basis of estimated ground-water budgets. The 

volume of ground water that may be allocated for 

development is assumed to equal an estimate of longterm mean annual ground-water recharge to a given 

hydrographic area or basin (Rush, 1968). Groundwater recharge to the topographically closed basins 

and other hydrographic areas of Nevada is from precipitation and may be augmented by interbasin flow or 

surface-water inflow from adjacent basins. Measuring 

ground-water recharge is difficult at local scales and 

not possible at regional scales with current technology. 

ABSTRACT C1 
Consequently, rather than measuring recharge, 

the approach in Nevada has been to estimate it on 

the basi~:·of ground-water discharge fro~ ;:t basin or 

hydrographic area. Before the development of ground 

water began in any given valley, the ground-water 

system was assumed to have been in equilibriumlong-term mean annual ground-water discharge was 

assumed: to be equal to the long-term mean annual 

recharge. Ground-water discharge from a valley or 

hydrographic area is by evapotranspiration from 

phreatophytes and bare soil or by interbasin flow to 

adjacenfvalleys. Interbasin ground-water flow to and 

from a b~sin may be surmised from water-level gradients, estimates of hydraulic conductivity, and estimates 

of aquif~! thickness or from estimated ground-water 

budget iJ)lbalances. Ground-water evapotranspiration 

can be measured at the local scale using micrometeorological methods. 

Estimates of ground-water evapotranspiration 

and estimates of interbasin ground-water flow from 

a valley ~ave been the foundations for estimating 

regional-ground-water recharge as a function of annual 

precipita~ion. Reconnaissance-level studies of the 

ground-water resources of Nevada began in 1945 and 

continu~d into the 1970's. These studies estimated 

ground-~ater evapotranspiration by mapping the areas 

covered by phreatophytes and applying evapotranspiration rates from early investigations of ground-water 

evapotranspiration from saltgrass by Lee (1912) in 

Owens Valley, Calif., and ground-water evapotranspiration from phreatophyte shrubs by White (1932) in 

Escalante Desert, Utah. Many of the valleys, or groups 

of adjacent valleys, studied during the late 1940's when 

the reconnaissance methods for estimating groundwater budgets were being developed, were assumed to 

be hydrologically closed; interbasin flow into or out of 

the valleys was assumed not to occur and was thus not 

included in the ground-water budgets. Precipitation 

falling in a basin was estimated from a map of annual 

precipitation in Nevada (Hardman, 1936). l.Jsing estimates of annual ground-water discharge from several 

valleys together with estimates of annual precipitation 

in the same valleys, a method was devised for estimating annual ground-water recharge as a function of 

annual precipitation (Maxey and Eakin, 1949; Eakin 

and others, 1951b, p. 26 and 80). 

A recently developed method for estimating 

ground-water evapotranspiration at regional scales 

(Chapter B of this report) and a recent map of annual 

precipitation in Nevada (G.H. Taylor, Oregon Climate 

Center, written commun., May 1997) provide an 

opportunity to reassess the ground-water budgets estimated by previous studies in Nevada. 

Values of estimated ground-water evapotranspiration and estimated recharge from precipitation given 

in tables C5, C7, and C13 have been rounded using the 

following rules. Numbers are rounded to the nearest 

100 acre-ft for values less than 10,000 acre-ft, to the 

nearest 500 acre-ft for values equal to or greater than 

10,000 acre-ft and less than 100,000 acre-ft, and to the 

nearest 1,000 acre-ft for values equal to or greater than 

100,000 acre-ft. Calculated values of ground-water 

evapotranspiration, volumes of precipitation, and 

recharge from precipitation given in tables C6, C9, 

C10, C11, C17, C18, and C19 are not rounded, to minimize rounding errors in subsequent calculations, to 

maintain precision, and do not imply accuracy. 

Purpose and Scope 

This chapter provides estimates of mean annual 

ground-water evapotranspiration at a regional scale, 

mean annual ground-water recharge from precipitation, 

and regional ground-water budgets and ground-water 

flow for selected valleys in eastern Nevada. The budgets were determined from estimates of ground-water 

evapotranspiration from phreatophyte plant cover 

using a vegetation index derived from Landsat data. 

Estimates of ground-water evapotranspiration combined with estimates of interbasin ground-water flow 

were used to estimate ground-water recharge as a function of precipitation. Ground-water budgets were estimated for 16 valleys in eastern Nevada and then used 

to define regional ground-water flow in that area. This 

study was conducted in cooperation with the Las Vegas 

Valley Water District and the Nevada Division of 

Water Resources. 

Study Area 

The study area covers 14,986 mi2 of eastern 

Nevada (fig. Cl), an area about 500 mi2 larger than the 

area covered by the states of Massachusetts, Connecticut, and Rhode Island. The study area includes, from 

northwest to southeast, Ruby, Clover, Independence, 

Goshute, Antelope, Newark, Long, Butte, Steptoe, 

Tippett, Little Fish Lake, Hot Creek, Little Smoky, 

Railroad (northern part), Jakes, and Spring Valleys in 

Elko, White Pine, Eureka, Lincoln, and Nye Counties 

C2 Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
,..Y·;_J·1 . 

. _· '· v. ,; :. _,_ . \ 

' .. _ ~DAHO ____ /'\., -~-~: .-------) 

. 

. 

• Reno 

Winnemucca . 

' • Carson City 

EXPLANATION 

- • • - Boundary of Great Basin- Modified 

from Harrill and others (1988) 

- · · - Topographic valley boundary 

1 Pilot 

·(. 

• Eiko :. · ~ ~ 

.f{: i : 

-t-V . ~ ( • •. • ( • • I 

. 1 . \), . 

{ . -~ ) ·r- \ I .)/.· .· r . : { t. ·. t . 

I Valley 

• ·. }_ : t • -~ I 

Eurek?-{ \ ,...;'.--/ Ely.. l .

1 

:. ,-\ t ·.· \ { c 

J .. r <. ~ . \ . . ". ~ 

;;_}) / ( Lu~d A, ~ ' 

\.• 

r -. 1· 

( Area of plates 2 and 3 

Area of plates 1 and 4 

Franklin" Las Vegas • 

Lake Playa ' 

. . 

I : 

v 

Base from U.S. Geological Survey digital data, 1 :100,000, 1978-88 

Universal Transverse Mercator Projection, Zone 11 

0 50 100 150 200 MILES 

0 50 100 150 200 KILOMETERS 

Figure C1. Great Basin and eastern Nevada study area. 

, .. 

. Salt Lake c;ty•\ 

ARIZONA 

. . 

J 

( 

INTRODUCTION C3 
(pl. 1, table Cl). The valleys approximately correspond 

to hydrographic areas 1 of the same name as defined by 

Rush (1968). 

Geography and Topography 

The study area covers a sparsely populated region 

of the central Great Basin in eastern Nevada (fig. Cl, 

pl. 1 ). Several valleys have no permanent residents and 

others have only a few isolated ranches. Small areas of 

irrigated agriculture in Ruby, Clover, Newark, Steptoe, 

Spring, Little Smoky, and Railroad Valleys use ground 

water that either is pumped or is discharged by springs. 

Ruby and Clover Valleys have extensive areas of subirrigated native pasture along the northwest part of each 

valley; most of this water is derived from surface runoff 

from the northern Ruby Mountains and East Humboldt 

Range. Much of the remaining rangeland in the study 

area is used for cattle grazing. 

Mining has been ubiquitous throughout the area; 

52 mining districts are within the study area (Smith, 

1976; Kleinhampl and Ziony, 1984; LaPointe and others, 1991). Mining activities began in the 1860's and 

continue to the present (1999) at several locations. Elements recovered, in order of occurrence, but not in 

value, are lead, silver, tungsten, copper, and gold. 

The city of Ely (pop. 4, 7 56 in 1990) is in the 

southern part of the study area in Steptoe Valley (fig. 

Cl; pl. 1). The towns of McGill (pop. 1,258 in 1990), 

Ruth (pop. unknown), and Duckwater (pop. 298 in 

1990) are the only other populated communities in the 

study area (pl. 1). Eureka (pop. 1,107 in 1990) is just 

west of the study area; Elko (pop. 14,736 in 1990) and 

Wells (pop. 1,256 in 1990) are to the northwest and 

north, respectively (pl. 1). Interstate 80 crosses the 

northern end of Independence and Goshute Valleys; 

U.S. Highway 50 crosses the central part of the study 

area from Eureka to Ely (pl. 1) and thence eastward into 

Utah. U.S. Highway 6 crosses the southern part of the 

study area from Hot Creek Valley through Railroad 

Valley to Ely in Steptoe Valley. U.S. Highway 93 connects Ely northward to Wells and Interstate 80, and 

southward toward southern Nevada. 

1

Formal hydrographic areas in Nevada were delineated 

systematically by the U.S. Geological Survey and Nevada 

Division of Water Resources in the late 1960's (Rush, 1968; 

Cardinalli and others, 1968) for scientific and administrative 

purposes. The official hydrographic-area names, numbers, and 

geographic boundaries continue to be used in Geological Survey 

scientific reports and Division of Water Resources 

administrative activities. 

Valleys and bounding mountain ranges of the 

study area trend generally north-south with the exception of the Ruby Mountains and East Humboldt Ranges 

on the north and the Quinn Canyon and Grant Ranges 

on the south, which trend northeast-southwest. The 

defining features of the central Great Basin in eastern 

Nevada are valleys whose lowest areas are nearly a 

mile or more above sea level with bounding mountain 

ranges that rise as much as a mile or more above the 

adjacent valley. The altitude of the valley floors (table 

Cl) ranges from 4,700 ft (Railroad Valley) to 6,500 ft 

(Little Fish Lake Valley) above sea level and averages 

about 5,800 ft above sea level. Mountain ranges bounding the valleys of the study area rise to altitudes of more 

than 10,000 ft in many locations. They include the 

rather low Pancake Range (pl. 1 ), which varies from 

7,000 to 8,000 ft, and rises to 9,240 ft at Portuguese 

Mountain, to the Ruby Mountains, which have large 

areas above 10,000 ft and rise to over 11,000 ft at King 

Peak (pl. 1), to the Snake Range, which rises to as much 

as 13,063 ft at Wheeler Peak (pl. 1). Clover, Independence, Newark, Railroad, Ruby, Spring, and Steptoe 

Valleys have large, well-defined playas. Little Fish 

Table C1. Names and areas of valleys included in eastern 

Nevada study area 1 

Area Altitude of 

lowest area 

Valley name Square of valley floor 

Acres miles (feet above 

sea level) 

Antelope Valley 255,683 399.5 5,600 

Butte Valley 652,333 1,019.3 6,000 

Clover Valley 292,099 456.4 5,600 

Goshute Valley 612,146 956.5 5,600 

Hot Creek Valley 658,493 1,028.9 5,200 

Independence Valley 360,677 563.6 5,600 

Jakes Valley 270,512 422.7 6,300 

Little Fish Lake Valley 276,471 432.0 6,500 

Little Smoky Valley 740,552 1,157.1 6,000 

Long Valley 419,850 656.0 6,100 

Newark Valley 509,264 795.7 5,900 

Railroad Valley 

(northern part) 1,369,718 2,140.2 4,700 

Ruby Valley 638,923 998.3 6,000 

Spring Valley 1,066,995 1,667.2 5,600 

Steptoe Valley 1,245,626 1,946.3 5,900 

Tippett Valley 221,588 346.2 5,700 

Total 2 9,590,900 15,000 

1 Calculated values are not rounded, to minimize rounding errors in 

subsequent calculations, except as indicated. 

2 Rounded to the nearest 100 acres or square miles. 

C4 Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
Lake in Little Fish Lake Valley and Ruby Lake in 

Ruby Valley are the only natural permanent lakes in 

the study area. Snow Water Lake in Clover Valley, 

Franklin Lake in northern Ruby Valley, Goshute Lake 

in Steptoe Valley, and Newark Lake in Newark Valley 

are present in many years, but disappear during periods 

of extended drought. Long and Tippett Valleys each 

have a small playa underlain by deep ground water. 

Many playas have water on them during the spring and 

early summer, especially in years of above average precipitation. Some playas become intermittent lakes during extended wet periods. 

Hydrogeology 

The geology of eastern Nevada is complex and 

has involved repeated episodes of sedimentation, folding, faulting, and volcanic activity. Consolidated rocks 

in the study area, ranging in age from Precambrian to 

late Tertiary, are exposed in the mountain ranges 

bounding the valleys. Unconsolidated deposits of Tertiary and Quaternary age underlie the valleys of the 

study area. The geologic framework of the region as it 

relates to ground-water hydrology has been summarized by Plume and Carlton (1988) and Plume (1996). 

Precambrian rocks, dominantly quartzite, occur 

in small areas of the southern Cherry Creek Range, 

northern Egan Range, and in large areas of the Schell 

Creek and Snake Ranges (Hose and Blake, 1976). 

Lower Paleozoic (Cambrian to Devonian) limestone 

and dolomite with minor shale, siltstone, sandstone, 

and quartzite comprise major parts of the southern 

Ruby Mountains, the Goshute Mountains, the southern 

Cherry Creek and the northern and southern Egan 

Ranges, the central Schell Creek Range, and the Fish 

Creek, Snake, White Pine, and Grant Ranges. Upper 

Paleozoic (Pennsylvanian to Permian) limestone and 

cherty limestone with interbedded shale and locally 

thick interbedded sandstone comprise major parts of 

the Pequop, Diamond, Maverick Springs, Butte, and 

Spruce Mountains, and the northern Cherry Creek, central Egan, and southern Schell Creek Ranges. The East 

Humboldt Range and the northern half of the Ruby 

Mountains consist of a complex of metamorphosed 

Paleozoic rocks and Mesozoic granitic rocks. Intrusive 

igneous rocks of Mesozoic and Cenozoic age crop out 

in many of the mountain ranges of the study area. Tertiary volcanic rocks dominate the Monitor, Hot Creek, 

Pancake, Quinn Canyon, and both Antelope Ranges, 

and occur locally in a number of the other mountain 

ranges in the study area. 

Winograd and Thordarson (1975) defined a 

hydrogeologic framework for southern Nevada (fig. 

C2). They combined the carbonate rocks of Middle 

Cambrian through Devonian age, which includes the 

upper Carrara Formation through the Devils Gate limestone, into a single hydrogeologic unit that they 

referred to as the lower carbonate aquifer. Overlying 

this aquifer, they defined an upper clastic aquitard that 

consists of the Devonian-Mississippian Eleana Formation. Above this aquitard, they defined an upper carbonate aquifer consisting of the PennsylvanianPermian Tippipah Limestone. 

These same geologic formations and hydrogeologic units, or their stratigraphic and commonly lithologic equivalents, are found throughout the study area 

in eastern Nevada (fig. C2). Plume and Carlton (1988), 

and later Dettinger (1989), Plume (1996), and Dettinger and Schaefer (1996) concluded that the two carbonate aquifer units of Winograd and Thordarson 

(1975) commonly are in fault contact and probably are 

connected hydraulically throughout most of Nevada. 

Consequently, Plume and Carlton (1988) considered 

there is a single carbonate-rock aquifer that can be 

divided into a lower part, equivalent to the lower 

carbonate aquifer of Winograd and Thordarson (1975), 

and an upper part, equivalent to the upper carbonate 

aquifer of Winograd and Thordarson (1975). The 

hydrogeologic terminology of Winograd and Thordarson (1975) is used in this report. 

The water-bearing properties of the Tertiary and 

Quaternary volcanic rocks overlying the carbonaterock aquifers are not well known except in a few local 

areas (Winograd and Thordarson, 1975; Glancy, 1986). 

They are considered as a single hydrogeologic unit for 

this study. Unconsolidated Tertiary and Quaternary 

basin-fill deposits are the units that yield most of the 

ground water in the study area. The hydraulic properties of these deposits have been described in some 

detail by Plume (1996). 

Climate 

The climate of the valleys of eastern Nevada, as 

most of the Great Basin, is a middle-latitude desert and 

steppe climate dominated by continental tropical air 

masses in the summer and continental polar air masses 

in the winter (Houghton and others, 1975, p. 13, 69-

70). The arid climate is characterized by hot summers 

and cold winters where annual precipitation commonly 

is less than 12 inches (table C2). The bounding mountain ranges receive more precipitation and have a 

INTRODUCTION CS 
0 

0'1 

Southern Eastern 

Nevada Nevada 

0 Southern hydrogeologic Grant, Quinn Canyon, hydrogeologic 

':r System Series Nevada1 units 1 and Egan Ranges2 Snake Range3 Ruby Mountains4 Goshute Mountains5 units6 m 

"S. 

(I) 

... Permian Arcturus Formation Arcturus Formation Pequop Formation Pequop Formation 

r> 

:c Upper Riepe Spring Limestone Riepe Spring Limestone Limestone and dolomite I Upper part of (I) Tippipah Limestone carbonate Riepe Spring Limestone carbonate-rock cc aquifer 1 c;· aquifer 

::::s Pennsylvanian 

!!. Ely Limestone Ely Limestone Ely Limestone Ely Limestone 

C) 

0 

c I I I I Diamond Peak Formation I Scotty Wash Quartzite I Diamond Peak Formation I Diamond Peak Formation ::::s 

Q, 

:e I Mississippian I Eleana Formation I 

Upper I Chainman Shale I Chainman Shale I Chainman Shale I Chainman Shale m I Clastic rocks clastic 

~ aquitard 

t:D 

c 

Q, 

cc 

(I) 

ur 

m I Devonian 

::::s 

Q, 

C) 

0 I Devonian and c Silurian ::::s 

Q, 

:e 

a 

~ I O"'ovicia" Lower ., carbonate I I I I 

I Lower part of 

0 Pogonip Group, aquifer Pogonip Group, Pogonip Group, Pogonip Group, Pogonip Group, carbonate-rock 

~~ undivided undivided undivided undivided undivided aquifer 

m 

m 

In 

co Upper Nopah Formation 

3 

z Dunderber Shale7 

(I) 

m < Lincoln Peak Formation Lincoln Peak Formation Bonanza King Q, Cambrian Middle Formation Limestone, dolomite, I Limestone and dolomite m Pole Canyon Limestone Pole Canyon Limestone and shale 

Carrara Formation 

Lower 

Lower Zabriskie Quartzite ~lastic I Pioche Shale I Pioche Shale I Pioche Shale I Pioche Shale I Clastic rocks 

aquitard 

1 Winograd and Thordarson (1975) 

2Tschanz and Pampeyan (1970), Hose and Blake (1976), and Kleinhampl and Ziony (1984) 

3Tschanz and Pampeyan (1970) and Hose and Blake (1976) 4Dudley (1967), Hose and Blake (1976), and Coats (1987) 

5coats (1987) 

6Piume and Carlton (1988) 7Member of the Nopah Formation 

8Member of the Orr Formation 

Figure C2. Correlation of stratigraphic and hydrostratigraphic units in southern Nevada and the eastern Nevada study area. 
Table C2. Climatic data for 1961-90 at selected valley 

locations in eastern Nevada. Locations are shown on plate 1 

[Digital data from Western Regional Climate Center, Desert Research 

Institute, University of Nevada, Reno, 1997.] 

Altitude Mean annual Annual 

(feet temperature precip- Station name above (degrees Fahrenheit) itation 

sea level) Maximum Minimum (inches) 

Arthur 6,300 57.6 30.4 15.33 

Duckwater 5,400 7.38 

Elko 5,075 62.4 30.9 9.95 

Ely 6,262 61.2 28.0 10.13 

Eureka 6,540 59.8 33.2 13.10 

Lund 5,565 64.9 30.9 10.46 

Ruby Lake 6,012 61.6 32.1 13.32 

Snowball Ranch 7,160 59.0 28.9 9.01 

Wells 5,650 59.6 28.5 10.59 

- · subhumid continental climate characterized by cold 

winters with moderate annual precipitation ranging 

·from 20 to 40 inches. The highest ranges in Nevada, 

including the Ruby Mountains and Snake Range within 

the study area, have a humid continental climate 

because of the abundant precipitation, greater than 30 

inches, at the higher altitudes. 

Summer maximum daily temperatures in the valleys of the study area typically exceed 90°F during late 

July and early August, and may exceed 100°F, with 

valleys at lower altitudes experiencing higher temperatures over longer periods of time. Daily minimum summer temperatures in most of the valleys range from the 

low 40's to low 50's, but in Steptoe Valley the summer 

minimum is about 10° lower. Maximum winter daily 

temperatures in the valleys range from 30° to 40°F in 

the northern part of the study area and are about 10° 

warmer in the southern part of the study area. Persistent 

temperature inversions develop in many of these valleys during some winters. Winter minimum daily temperatures commonly range from 10° to 20°F, but may 

go as low as -30° to -40°F especially in the northern 

part of the study area. Maximum and minimum daily 

temperatures decrease with altitude in the mountain 

ranges bounding the valleys. No temperature records 

are available for the high-altitude areas. However, in 

the absence of temperature inversions, the temperature 

lapse rate, which is the rate of temperature decrease 

with altitude, may be as much as 5.9°F per 1,000 feet 

on the basis of atmospheric soundings by the U.S. 

Weather Service at Winnemucca, Elko, and Ely, Nev. 

This suggests temperatures at higher altitude in the surrounding mountains may be 15° to 25°F cooler than in 

the valleys. 

Vegetation 

The diverse climate zones of the Great Basin and 

the study area lead to diverse vegetation zones. In the 

arid zones of the lower valley floors are plants of the 

salt desert and shadscale-greasewood communities. 

Plants of these two zones are discussed in more detail 

below. 

Beyond the valley floors are alluvial fans leading 

to the base of the surrounding mountains. On the fans 

are plants of the Great Basin sagebrush community, 

which commonly includes big sagebrush (Atremisia 

tridentata), dwarf sagebrush (A. arbuscula), and black 

sagebrush (A. arbuscula var. nova), and may include 

spiny hopsage (Grayia spinosa), bitterbrush (Purshia 

tridentata, and P. glandulosa), and mormon tea (Ephedra viridis). Before the introduction of livestock, this 

zone included numerous species of grasses, with areas 

that received greater precipitation having a higher percentage of grass to shrub. Although grasses are common in this zone today, they may not be as extensive as 

they were originally (Trimble, 1989, p. 101, 110). 

Beginning in the middle to upper part of the fans, 

between 6,000 and 7,000 ft in altitude, is the lower border of the pinyon-juniper woodland assemblage, which 

may extend to altitudes of nearly 9,000 ft (Charlet, 

1996, p. 233). This assemblage is characterized in the 

Great Basin by generally open stands of singleleaf pinyon (Pinus monophylla) and Utah juniper (Juniper 

oseosperma) with an understory of sagebrush and coolseason grasses (Trimble, 1989). Juniper dominates in 

the lower altitudes near the valley floor with pinyon 

becoming more common with increasing altitude and 

generally dominating above 7,000-7,500 ft. Above 

about 7,500 ft, mountain mahogany ( Cercicarpus ledifolius and C. inticatus) and aspen (Populus tremuloides) may be included in this assemblage. 

A pine-fir forest should occur above the pinyonjuniper woodland, but many of the ranges in the central 

Great Basin, including some of those of the study area, 

have no forest above the woodland. Instead, many of 

the highest ranges, such as the Schell Creek and Snake 

Ranges, have a double timberline, with the lower timberline occurring between about 8,000 and 8,500 ft. 

Here, the pinyon-juniper woodland stops, but sagebrush, bitterbrush, and grasses together with small 

groves of curlleaf mountain mahogany and aspen fill 

INTRODUCTION C7 
the zone of the fir-pine forest for the next 500 to 1,500 

ft in altitude to the lower border of the subalpine zone. 

The trees of the pine-fir forest zone are present in small 

stands on protected north-facing slopes and even at 

lower altitudes in well-watered washes and canyons. 

The subalpine zone begins at about 9,000-9,500 ft 

and extends to the upper timberline between 11,000 

and 11,500 ft. The trees of this zone include white bark 

pine (Pinus monticola), limber pine (Pinus flexilis), 

bristlecone pine (Pinus longaeva ), Engleman spruce 

(Picea englemanii), and aspen. Above timberline, 

alpine tundra is found in the highest ranges of the study 

area, including the Ruby Mountains, and the East Humboldt, Schell Creek, and Snake Ranges. 

The plants of the salt desert and shadscale-greasewood communities found at the lowest altitudes in the 

valleys, however, are of most interest in the present 

study. These communities include the phreatophytes 

that consume and discharge ground water by evapotranspiration. Some valleys in the study area have a 

playa at the lowest part of the valley, which commonly 

is underlain by a shallow water table. The playas range 

in size from a small one in Long Valley (about 6,000 

acres) to the large playa in Railroad Valley (about 

36,000 acres). Surrounding these playas, or in the 

lowest parts of the valleys with no playa, are plants of 

the salt desert community, including iodine bush (also 

called pickleweed; Allenrolfea occidentalis), saltsage 

(Atriplex tridentata), and saltgrass (Distich/is spicata 

var. stricta). Iodine bush is reported to grow in areas 

with a depth to water of as much as 20 ft (Robinson, 

1958, p. 32). Saltgrass, the most common phreatophyte 

in this zone, grows mostly in areas where the depth to 

water is less than about 8 ft, but has been reported to 

grow in areas where the water table is as much as 12 ft 

deep (Blaney and others, 1933, p. 50). 

Beyond this fringe of vegetation, around the margin of the playas, is the shadscale-greasewood plant 

community. Within this plant association are found not 

only greasewood (Sarcobatus vermiculatus) and shadscale (Atriplex confertifolia), but also saltbush (also 

known as chamiso; Atriplex canescens), spiny hopsage 

(Grayia spinosa), winterfat (Ceratoides lanata), and 

where soils and ground water are less saline, rabbitbrush ( Chrysothamnus nauseosus) and big sagebrush 

(Artemisia tridentata). 

Shadscale and spiny hopsage are not commonly 

included as phreatophytes, but have been observed 

growing with greasewood in areas where the depth 

to water is at least 15 ft and therefore are assumed to 

transpire ground water at rates similar to those of 

greasewood. White (1932, p. 38) discusses the occurrence of shadscale with greasewood and rabbitbrush in 

areas of shallow ground water, but does not suggest a 

limiting depth to water. Saltbush is found where ground 

water is from about 8 ft to as much as 62 ft below land 

surface (Robinson, 1958, p. 33). 

Greasewood is the principal phreatophyte, other 

than riparian, in the shadscale-greasewood zone of 

western Nevada (Billings, 1951) and its range is more 

extensive than that of big sagebrush in western North 

America (Robertson, 1983). Greasewood covers about 

12 million acres from Canada to Mexico, but prefers 

the cold deserts north of 37°N latitude (Shreve, 1942). 

Greasewood occurs in areas where the depth to ground 

water ranges from about 5 ft to 35 ft and perhaps to as 

much as 60ft (Robinson, 1958, p. 39). White (1932, p. 

33) noted that greasewood required at least 3ft of 

unsaturated soil most of the time. 

Rabbitbrush grows in areas where the depth to 

ground water is less than about 35 ft. Robinson (1958, 

p. 34) suggests a maximum depth to water for rabbitbrush of 15 ft, conventional wisdom has suggested a 

maximum depth of 25ft, and Mower and Nace (1957, 

p. 18) suggest a maximum depth of 35 ft. 

Big sagebrush has been observed in some valleys 

of the Great Basin in association with rabbitbrush in 

areas where the water table is about 12 to 15ft below 

land surface, and in these circumstances appears to be 

a phreatophyte as well. White (1932, p. 43), however, 

assumed on the basis of water-level fluctuations, that 

sagebrush used little or no ground water even in the 

Escalante Valley of Utah where the depth to water was 

less than 15ft. Mozingo (1987, p. 271) reports that 

sagebrush has roots that grow as deep as 12 ft and commonly penetrate to the capillary zone above the water 

table. 

Previous Ground-Water Studies 

Studies to measure or estimate the consumptive 

use of ground water by phreatophytes, and thus a large 

part of the discharge component of the ground-water 

budget in the Great Basin, began in 1910 with the study 

by Lee (1912) and continued in the 1920's with the 

work of White (1932). Additional studies were done by 

other investigators through the 1930's (Blaney and oth- · 

ers, 1930, 1938; summarized by Young and Blaney, 

1942), 1940's (Gatewood and others, 1950), and continued into the 1960's with the study by Robinson 

C8 Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
', 

(1970). In the late 1940's, investigators in Nevada used 

the results of some of the earlier evapotranspiration 

studies to make estimates of the recharge component of 

the ground-water budget (Maxey and Eakin, 1949; 

Eakin and others, 1951 b). These methods have been 

used in ground-water studies in Nevada up to the 

present time. 

Ground-Water Discharge Studies 

Among the earliest studies to measure the consumptive use of ground water by evapotranspiration 

from saltgrass and native shrubs and evaporation from 

bare soil were those of Lee (1912) and White (1932). 

Lee (1912) performed evapotranspiration-tank studies 

in 1910 and 1911 near Independence, Calif. (fig. Cl), 

in the Owens Valley in an attempt to determine groundwater evapotranspiration from saltgrass and bare soil in 

relation to the depth to ground water. Similar evapotranspiration-tank studies were done by White (1932) 

in 1926 and 1927 to determine ground-water evapotranspiration from alfalfa, saltgrass, greasewood, and 

bare soil in the Escalante Desert near Milford, Utah 

(fig. C1). 

These, as well as subsequent, evaporation-tank 

studies all used similar techniques, as discussed in 

Chapter A of this report (see section titled "Previous 

Studies"). Some of the studies were performed continuously for 12 months while others were operated only 

from April or May to October; the studies were from 1 

or 2 years. 

Lee's early study of saltgrass (1912) seemed to 

demonstrate a clear relation between evapotranspiration of ground water and the depth to ground water. 

Although subsequent studies (Blaney and others, 1930, 

1938; Young and Blaney, 1942) produced similar relations, an analysis of these data by Weeks and others 

( 1987) demonstrated that depth to ground water does 

not adequately define a unique relation to ground-water 

evapotranspiration by saltgrass. The locations of these 

evaporation-tank studies ranged from about 34 o to 

about 38°N in latitude, from about 1,500 ft to over 

3,000 ft in altitude, and from the coastal climate of 

southern California to the continental climate of southem Colorado. None of these studies provided a measure of the amount of vegetation, such as density or leaf 

area index. 

Studies by White (1932) attempted to determine 

ground-water evapotranspiration from alfalfa, saltgrass, greasewood, and bare soil. White (1932) also 

installed a number of small-diameter monitoring wells 

in areas of native vegetation underlain by shallow 

ground water and measured small diurnal fluctuations 

of ground-water levels that were interpreted to be 

caused by the evapotranspiration of ground water during the day. An expression was developed relating the 

discharge of ground water to the specific yield of the 

water-bearing sediments and the 24-hour rate of waterlevel change plus net water-level change (White, 1932, 

p. 61). Soil samples were taken to determine appropriate values of specific yield. The volume of ground 

water discharged then was determined from the diurnal 

water-level fluctuations. This volume was related to 

biomass production and converted to areal estimates of 

ground-water discharge based, presumably, on areal 

estimates of plant canopy volume. White (1932, p. 86-

87) concluded that, in the Escalante Desert, saltgrass 

and meadowgrass in areas where the depth to ground 

water was between 0 and 5 ft consumed about 1 ft of 

ground water a year, and that greasewood, rabbitbrush, 

and shadscale consumed about 0.15 ft/yr in areas with 

a depth to ground water of 8 to 30ft, and about 0.42 

ft/yr, when evaporation of ground water from bare soil 

was included, in areas with a depth to ground water of 

less than 8 ft. Evaporation of ground water from bare 

soil can be important in areas where the depth to 

ground water is as much as 5 to 8 ft below land surface. 

Robinson (1970) studied ground-water evapotranspiration by woody phreatophytes in the Humboldt 

River valley near Winnemucca, Nev., from 1963 to 

1967. Evapotranspiration tanks were planted with 

greasewood, rabbitbrush, willow, and wild rose; one 

tank contained bare soil. Robinson (1970, p. 31-32) 

concluded, on the basis of tank experiment data, that 

the consumption of ground water by greasewood 

ranged from an average of about 0.6 ft/yr to about 0.8 

ft/yr from 1963 to 1967. Rabbitbrush transpired an 

average of about 1.1 ft/yr from 1964 t<;> 1967. Depths to 

ground water in the greasewood tanks ranged from 5 to 

8 ft and in the rabbitbrush tanks, from 5 to 6 ft. These 

rates are considerably greater than the rates reported by 

White, but are difficult to compare because of a lack of 

comparable canopy density and volume data for the 

two studies. 

More recent studies of evapotranspiration by 

rangeland vegetation have used micrometeorological 

methods to measure total above-canopy fluxes of sensible and latent heat. Malek and others ( 1990) measured evapotranspiration from the moist playa and 

playa margin of Pilot Valley, Utah. Duell (1990) completed similar studies for several different desert shrub 

INTRODUCTION C9 
and grass communities growing in areas of shallow 

ground water in Owens Valley, Calif. Czarnecki ( 1997) 

measured evapotranspiration at Franklin Lake Playa, 

Nev., and Weeks and others (1987) studied evapotranspiration by. salt cedar, alkali sacaton, kochia, and grass 

in the Pecos River Valley between Acme and Artesia, 

N. Mex. Evapotranspiration rates determined by these 

studies are somewhat less useful in determining 

ground-water evapotranspiration because they also 

include evapotranspiration of precipitation and soil 

moisture as well as evapotranspiration of ground water. 

Of the studies cited above, comparative plant density 

and volume information is given only by Duell (1990). 

Evapotranspiration from rangeland shrubs was 

studied at several locations in the central and western 

Great Basin from 1988 to 1994 (Nichols, 1994). The 

general applicability of an energy-combination model 

(Shuttleworth and Gurney, 1990) for partitioning 

energy budgets, and hence evapotranspiration, between 

the soil and canopy of sparse-canopy rangeland vegetation was demonstrated using data from central Nevada 

(Nichols, 1992a). Using the results of this model, calibrated for study sites underlain by shallow ground 

water in west-central Nevada, estimates were made of 

ground-water evapotranspiration rates for greasewood, 

rabbitbrush, and sagebrush ranging from 0.5 to 0.7 ft/yr 

(Nichols, 1992b, 1993). 

The analysis was expanded to include data and 

estimated transpiration from phreatophytes shrubs 

from additional sites and a functional relation was 

developed between ground-water transpiration from 

phreatophyte shrubs and the depth to ground water, 

shrub density, and shrub leaf area index (Nichols, 

1994). Following field studies of evapotranspiration 

from saltgrass areas in southern Nevada (Nichols and 

others, 1997), the analysis was further extended to 

develop a functional relation between ground-water 

evapotranspiration and plant cover (Chapter A of this 

report). Ground-water evapotranspiration estimated by 

this relation includes evapotranspiration from phreatophyte grasses and shrubs and from associated bare soil. 

The analysis of the present study uses the functional 

relation between ground-water evapotranspiration and 

plant cover (Chapter A) combined with satellite-dataderived vegetation indices (Chapter B) to estimate 

regional ground-water evapotranspiration. 

Recharge Studies 

Several methods for estimating regional groundwater recharge from precipitation have been developed 

over the years and have been summarized by Lerner 

and others (1990). Ground-water- resources studies in 

Nevada, mostly eastern Nevada, during the late 1940's, 

led investigators to conclude that ground-water 

recharge by precipitation on the valleys of the region 

could be estimated from knowledge of ground-water 

discharge by evapotranspiration from phreatophytes on 

the valley floor. This is most succinctly stated by 

Maxey and Eakin (1949, p. 40), who developed the 

method of estimating recharge in Nevada: 

(R)echarge studies ... consisted of estimating the ground-water discharge by natural 

losses from 13 valleys in east-central Nevada. 

The recharge for each valley was also estimated using the rainfall-zone map as a basis. 

The recharge estimates were then balanced 

by trial-and-error with the discharge estimates. 

This excerpt makes clear that ground-water-discharge was the controlling factor in developing estimates of recharge from precipitation. Estimates of 

ground-water discharge by evapotranspiration were 

assumed reasonable and reliable and the precipitation 

as derived from the precipitation map of Nevada (Hardman, 1936) also was assumed reasonable and reliable. 

Two other assumptions, though not explicitly stated, 

also were made: (1) that many, if not most of these valleys were hydrologically and topographically closed 

and that all ground water discharged by evapotranspiration from phreatophytes and springs represented the 

approximate long-term annual discharge and (2) that 

recharge to the alluvial aquifer beneath the valley was 

equal to the long-term annual discharge. 

Eleven of the 13 valleys in which the recharge 

method was developed included Ruby, Clover , Independence, Goshute-Antelope (which included a somewhat different area for Antelope Valley than defined by 

Cardinalli and others (1968) and used herein), Hot 

Creek, Railroad, Reveille, Kawich, Penoyer, and White 

River Valleys (pl. 1). The other two valleys included in 

the original study are uncertain. Watson and others 

(1976) list 19 valleys reportedly included in the development of the recharge estimation method. The earliest 

published reports (Maxey and Eakin, 1949; Eakin, 

1950; Eakin and others, 1951 b) state that the valleys 

included in the study were in east-central Nevada; 

therefore, Diamond Valley and Spring Valley (Watson 

and others, 1976, p. 340) may be the remaining 2 valleys (pl. 1) needed to complete the list of 13, although 

no reports dating to the 1940's or early 1950's are 

known for these valleys. 

C10 Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
The areas covered by phreatophyte shrubs and 

grasses were mapped or estimated in the 13 selected 

valleys of east-central Nevada (Maxey and Eakin, 

1949; Eakin and others, 1951b). Using ground-water 

evapotranspiration values published by Lee (1912) and 

White (1932), estimates of total ground-water evapotranspiration were made for each of the valleys. The 

volume of precipitation falling on each valley was estimated for each of the precipitation zones shown on the 

existing precipitation map of Nevada (Hardman, 1936). 

The precipitation zones on this map showed areas of 

precipitation of less than 5 inches, 5 to less than 8 

inches, 8 to less than 12 inches, 12 to less than 15 

inches, 15 to less than 20 inches, and 20 inches and 

greater. Precipitation of less than 8 inches was assumed 

to produce no ground-water recharge. Using the estimated ground-water evapotranspiration for each valley, or group of valleys, as the assumed recharge from 

precipitation, coefficients by which to multiply the volume of precipitation in each of the remaining four precipitation zones were determined by trial-and-error 

(Maxey and Eakin, 1949; Eakin and others, 1951 b, 

p. 26, p. 80, p. 151); the coefficients they derived 

were 0.03, 0.07, 0.15, and 0.25 for the 8-12, 12-15, 

15-20, and 20-inch-and-greater zones, respectively. 

The coefficients were, in effect, the percentage of precipitation in each zone that reached the ground-water 

reservoir (Maxey and Eakin, 1949, p. 40). 

Reconnaissance Ground-Water Studies 

The methodologies developed during these early 

ground-water resources investigations provided the 

framework for a long-term program to define the 

ground-water resources of Nevada. These reconnaissance studies began in 1960 (Eakin, 1960) and concluded in 1974 (VanDenburgh and Rush, 1974). The 

results were a series of reconnaissance reports that 

describe the water resources of 219 valleys in 60 

reports with a strong emphasis in most reports on 

ground-water budgets. Reconnaissance studies of the 

water resources of valleys in the present study area 

(table C3) include those for Newark Valley (Eakin, 

1960); Long Valley (Eakin, 1961); Spring Valley 

(Rush and Kazmi, 1965); Little Fish Lake, Hot Creek, 

and Little Smoky Valleys (Rush and Everett, 1966); 

Steptoe Valley (Eakin and others, 1967); Butte Valley 

(Glancy, 1968); Tippett and Antelope Valleys (Harrill, 

1971); and Railroad Valley (VanDenburgh and Rush, 

1974). The subsequent allocation of ground-water 

Table C3. Previous reconnaissance-level ground-water resources investigations for valleys 

in eastern Nevada study area 

Valley 

Antelope Valley 

Butte Valley 

Clover Valley 

Goshute Valley 

Hot Creek Valley 

Independence Valley 

Jakes Valley 

Little Fish Lake Valley 

Little Smoky Valley 

Long Valley 

Newark Valley 

Railroad Valley 

Ruby Valley 

Spring Valley 

Steptoe Valley 

Tippett Valley 

Reference 

Eakin and others (1951a) 

Harrill ( 1971) 

Glancy (1968) 

Eakin and Maxey (1951 b) 

Eakin and others (1951a) 

Maxey and Eakin (1951) 

Rush and Everett ( 1966) 

Eakin and Maxey ( 1951 b) 

Maxey and Eakin ( 1949) 

Rush and Everett ( 1966) 

Rush and Everett ( 1966) 

Eakin (1961) 

Eakin (1960) 

Maxey and Eakin (1951) 

VanDenburgh and Rush (1974) 

Eakin and Maxey (1951a) 

Rush and Kazmi ( 1965) 

Eakin and others ( 1967) 

Harrill ( 1971 ) 

Report series and number 1 

Bulletin 12 

Reconnaissance 56 

Reconnaissance 49 

Bulletin 12 

Bulletin 12 

Bulletin 12 

Reconnaissance 38 

Bulletin 12 

Bulletin 8 

Reconnaissance 38 

Reconnaissance 38 

Reconnaissance 3 

Reconnaissance 1 

Bulletin 12 

Reconnaissance 60 

Bulletin 12 

Reconnaissance 33 

Reconnaissance 42 

Reconnaissance 56 

1 Refers to Water Resources Bulletins and Ground-Water Resources Reconnaissance series of reports published by 

Nevada Department of Conservation and Natural Resources in cooperation with U.S. Geological Survey. See References Cited 

section for complete citation. 

INTRODUCTION C11 
resources by the State of Nevada has been based on 

the ground-water' budgets published in these and other 

reconnaissance-series reports. 

The reconnaissance studies were part of a cooperative program between the State of Nevada and the 

U.S. Geological Survey to determine the quantity, 

quality, and distribution of the water resources of the 

state (Shamberger, 1962). The program, as proposed, 

included several local and regional studies, research 

investigations, and data collection activities. As part of 

this program 

... the preliminary reconnaissance studies (were) first-stage hydrologic studies ... 

which summarize( d) hydrologic observations. 

.. These studies suggest the potentials of 

water development, but only tentatively 

because of lack of data ... Nevertheless, they 

provide the basic framework for second, third, 

and fourth-stage hydrologic studies ... 

(Shamberger, 1962, p. 14). 

As such, the ground-water resources reconnaissance studies were never intended to provide definitive 

ground-water budgets for the areas studied. Rather, the 

studies were intended to provide a preliminary estimate 

and guide for more comprehensive future studies given 

the availability of new data, methods, and technologies. 

The present study builds on the hydrologic 

knowledge provided by the reconnaissance studies and 

subsequent studies, uses new information on groundwater evapotranspiration determined from field studies 

from 1988 to 1994, uses new estimates of annual precipitation for Nevada, and utilizes current technologies 

in the form of satellite-derived remotely sensed data. 

The present study follows from the earlier reconnaissance studies and provides a new set of estimates of 

regional ground-water budgets that update the older 

reconnaissance estimates. 

ESTIMATED GROUND-WATER 

DISCHARGE AND RECHARGE 

Ground-water evapotranspiration was estimated 

as a function of plant cover (Chapter A of this report). 

Plant cover, in tum, was estimated on a regional scale 

from a Landsat-data-derived vegetation index (Chapter 

B). Regional ground-water evapotranspiration then 

was estimated using the estimated regional plant cover. 

These estimates of ground-water discharge by evapotranspiration and estimates of interbasin ground-water 

flow for the valleys in the study area were used to 

derive estimates of regional ground-water recharge 

from precipitation. As such, the estimated recharge is 

not an independent estimate, but is based on the estimated discharge from the valleys. 

Coefficients for estimating recharge from precipitation zones of 8 to less than 12 inches, 12 to less than 

16 inches, 16 to less than 20 inches, 20 to less than 34 

inches, and 34 inches and greater were calculated using 

a multiple linear regression model based on estimated 

ground-water evapotranspiration and interbasin flow. 

The coefficients represent the percentage of precipitation in each zone that recharges the ground-water system. Ground-water budgets for individual valleys were 

balanced, where needed, by interbasin ground-water 

flow from or to adjacent valleys. Many occurrences of 

interbasin flow have been suggested or proposed by 

earlier studies. lnterbasin ground-water flow was not 

assumed in the absence of supporting geologic, geophysical, or hydrologic evidence. 

Discharge by Evapotranspiration 

The discharge of ground water by evapotranspiration was estimated for the valleys of the study area 

using the method described in Chapter B. This method 

estimates ground-water evapotranspiration as a function of phreatophyte plant cover. Plant cover was estimated from a vegetation index derived from Landsat 

data using 1985 and 1989 Landsat scenes of the study 

area. Details of the estimated ground-water evapotranspiration from each valley for 1985 and 1989 are given 

in table C17 (at the end of this chapter) and by Smith 

and others (2000). Weighted-average phreatophyte 

plant cover ranged from an estimated 3.6 percent in 

Tippett Valley in 1985 to 68.8 percent in a spring-discharge area of Goshute Valley in 1989. Annual groundwater evapotranspiration rates ranged from a minimum 

of less than 0.1 ft to a maximum of about 2.6 ft. 

Ground-water evaporation from bare soil and playa 

areas was estimated to be about 0.15 ft on the basis of 

field studies in Railroad Valley (M.J. Johnson, U.S. 

Geological Survey, written commun., 1994), but probably ranges from near zero in areas of deep ground 

water to as much as 1.25 ft (Stannard, 1997, p. 35) in 

areas of very shallow ground water (1 ft or less). 

The present study estimated summer (May 

through September), winter (October through April), 

and annual ground-water evapotranspiration (Chapter 

A). Winter ground-water evapotranspiration may 

account for as much as 26 percent of the total annual 

C12 Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
ground-water evapotranspiration. The early reconnaissance studies estimated what was referred to, in the 

early reports, as a growing season ground-water 

evapotranspiration, with no definition of the growing 

season. Subsequent studies referred to this same 

evapotranspiration as annual ground-water evapotranspiration. Robinson ( 1970) went to some length to 

define a growing season for the phreatophytes of his 

study and concluded that it extended from sometime in 

April to sometime in October, implying no ground 

water evapotranspired from October to April. 

However, studies by Duell (1990) and Nichols 

and others (1997) demonstrated that ground-water 

evapotranspiration continues through the winter 

months in areas of shallow ground water. Most of the 

winter evapotranspiration is evaporation of ground 

water from bare soils. Some transpiration occurs during 

the winter months, as defined in this study, because 

phreatophyte shrubs remain green well into October, 

and on occasion into November. Shrub growth begins 

in April. During periods in the winter when soils near 

the surface are frozen, soil moisture and soil-water 

vapor derived from ground water continue to move 

toward the surface and accumulate in response to soilwater tension gradients. When the frozen surface soils 

thaw, the ground-water-derived soil moisture is evapotranspired. 

Evapotranspiration Rates in 1985 and 1989 

Ground-water evapotranspiration from the study 

area was estimated for 1985 and 1989. Precipitation 

over the study area was below normal (average for the 

30-year period 1961-90) during 1985 and 1989 (table 

C4). Significantly however, 1985 followed 3 years of 

well above-normal precipitation over most of the study 

area and 1989 followed 3 years of near- to below-normal precipitation over most of the study area (table 

C4). Plant cover was estimated for each valley of the 

study area from a satellite-data-derived vegetation 

index (Chapter B) and phreatophyte areas in each valley were mapped in the field using U.S. Geological 

Survey 1 :24,000-scale topographic quadrangle maps. 

The distribution of phreatophyte plant cover for 1985 is 

shown on plate 2 and for 1989 on plate 3. These plates 

also show the distribution of estimated ground-water 

evapotranspiration because it is directly related to plant 

cover (Chapter A). The generally wetter conditions 

preceding 1985 are indicated by water on the playas of 

Newark, Steptoe, and Spring Valleys, in Franklin Lake 

and Ruby Lake in Ruby Valley, and in Snow Water 

Lake in Clover Valley (pl. 2). These lakes, except for 

Ruby Lake, had dried up by 1989 (pl. 3). 

Interestingly though, plant cover was somewhat 

greater in many of the valleys in 1989 than in 1985. 

This is most readily seen by comparing the plant cover 

in 1989 in Goshute, Independence, Butte, and Steptoe 

Valleys (pl. 3, table C17) with the plant cover in these 

same valleys in 1985 (pl. 2, table C17). Plant cover was 

about the same in both years in Railroad, Little Fish 

Lake, Hot Creek, Little Smoky, and Newark Valleys. 

Plant cover in Spring Valley was less in 1989 than in 

1985. These changes, however, were caused by rather 

small changes in the amount of plant cover in areas 

where the cover is 20 percent or less. These areas are 

covered by phreatophyte shrubs, the numbers or density of which did not change between 1985 and 1989. 

Table C4. Mean annual and annual precipitation for selected stations and time periods, eastern Nevada. 

Station locations shown on plate 2 

U.S. Weather Mean annual precipitation (inches) ___ Annual precipitation (inches) 

Station name 1961-90 1982-84 1986-88 1985 1989 

Elko 10.13 15.07 9.85 9.89 6.60 

Ely 9.01 11.03 8.97 6.98 6.18 

Eureka 10.56 16.08 8.20 7.89 8.66 

Lund 13.10 19.15 11.12 6.82 7.21 

Ruby Lake 9.95 14.14 7.14 7.30 7.88 

Snowball Ranch 13.22 19.44 10.85 10.84 10.28 

Wells 10.46 16.38 10.29 11.22 7.46 

ESTIMATED GROUND-WATER DISCHARGE AND RECHARGE C13 
The changes were caused solely by increases or 

decreases in shrub leaf area index, LA/p. For example, 

an area in 1985 with a shrub density, d, of 0.20 (20 percent) and shrub leaf area index, LA/p, of 1.5, would 

have a plant cover, Cp, of 0.075 (7.5 percent), which 

places such an area in the less-than-10 percent plant 

cover zone. This same area in 1989, with the same 

shrub density, d, of 0.20 (20 percent) but with a shrub 

leaf area index, LA/p, of 2.5 would have a Cp of 0.125 

(12.5 percent), which would move the area from the 

less-than-10 percent plant cover zone into the 10-20 

percent plant cover zone. This change is readily seen in 

the data given in table C 17 at the end of this chapter. 

In Goshute Valley in 1985, for example, 4,197 

acres were classified as bare soil, 129,981 acres with 

less than 10 percent plant cover, and 1,178 acres with 

10-20 percent cover. In 1989, 4,156 acres that previously had such sparse vegetation that they were considered bare soil now had enough vegetation to be moved 

into the less than 10 percent zone while the leaf area of 

shrubs on 11, 165 acres of the less than 10 percent zone 

had increased enough to move these areas into the 10-

20 percent zone (fig. C3). The average plant cover 

increased slightly in the less than 10 percent zone from 

4.7 percent in 1985 to 7.8 percent in 1989, but 

decreased slightly in the 10-20 percent zone from 13.9 

percent in 1985 to 12.5 percent in 1989. 

The reasons for these small, but significant, 

changes in shrub leaf area index are uncertain. Several 

possible explanations, however, are offered. The 

higher-than-normal precipitation during the 3 years 

before 1985 may have left the soils in some of the lower 

30,000 

25,000 

20,000 

CJ) 

w 

a: 15,000 0 

<( 

10,000 

5,000 

0 

0 10 20 30 40 50 60 70 

PLANT COVER, IN PERCENT 

areas of the valley floors wet enough that it inhibited 

spring growth of greasewood, which is the dominant 

shrub in the areas that exhibited most of the change in 

plant cover. Groeneveld ( 1989) reported significant 

dieback by greasewood under flooded conditions. Robertson (1983, p. 315) also reported that greasewood 

dies when the water table is at land surface and White 

(1932, p. 33) suggested that greasewood preferred 

about 3 ft of aerated soil. 

Another explanation for the difference in leaf area 

between the 2 years may be related to nutrients. Groeneveld ( 1989) has suggested a correlation between the 

depth distribution of greasewood roots and the availability of nitrogen, presumably from plant detritus 

accumulated at land surface. The availability of nitrogen from this source also may be a factor in leaf development. If so, then this source of nitrogen may have 

been depleted by the higher-than-normal precipitation 

during the 3 years before 1985, but may not have been 

depleted by the below-normal precipitation during the 

3 years before 1989. Factors other than these, or in 

addition to these, may be responsible for the differences in leaf area observed in 1985 and 1989; determination of these factors by other investigations may be 

important in understanding the dynamics of rangeland 

vegetation, but are beyond the scope of this work. Estimated ground-water evapotranspiration from the 

valleys of the study area in 1985 and 1989, and the estimated mean annual ground-water evapotranspiration 

from each valley is summarized in table C5. 

Ground-water evapotranspiration from specific 

land-cover zones, the estimated weighted-mean plant 

80 90 

cover for the zone, the area of the zone, 

and annual estimated ground-water 

evapotranspiration rate are summarized in table C6; details for each 

valley for each year, including the estimated summer (May through September), winter (October through April), 

and annual ground-water evapotranspiration are given in table C17 at the 

end of this chapter. Slightly more than 

13 percent of the study area was covered by phreatophytes, bare soil, or, in 

1985, water-covered playas and lakes 

(table C6). Areas with plant cover 

1 00 equal ~o or greater than 20 percent 

Figure C3. Distribution of plant cover in Goshute Valley, 1985 and 1989. 

compnsed only about 9 percent of the 

total phreatophyte area in 1985 and 

about 8 percent in 1989; the remaining 

C14 Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
Table CS. Estimated ground-water evapotranspiration from phreatophytes, bare soil, 

and open water, eastern Nevada study area, for 1985, 1989, and mean annual conditions 1 

Estimated ground-water evapotranspiration (acre-feet) 

Valley 

1985 1989 Mean annual 

Antelope Valley 1,900 6,200 4,000 

Butte Valley 37,000 60,000 44,500 

Clover Valley 82,000 87,000 84,500 

Goshute Valley 28,500 83,500 42,500 

Hot Creek Valley 5,000 4,900 5,000 

Independence Valley 42,500 63,500 47,000 

Jakes Valley 600 500 600 

Little Fish Lake Valley 11,000 10,000 9,700 

Little Smoky Valley 5,400 6,700 6,000 

Long Valley 9,200 12,500 11,000 

Newark Valley 59,000 62,000 60,500 

Railroad Valley 

(northern part) 86,500 83,500 85,000 

Ruby Valley 2157,000 2177,000 2 167,000 

Spring Valley 102,000 77,500 90,000 

Steptoe Valley 118,000 137,000 128,000 

Tippett Valley 900 4,900 2,900 

Total 746,000 877,000 788,000 

1 Numbers are rounded to the nearest 100 acre-ft for values less than 10,000 acre-ft, to the nearest 500 acre-ft 

for values equal to or greater than 10,000 acre-ft and less than 100,000 acre-ft, and to the nearest 1,000 acre-ft for 

values equal to or greater than 100,000 acre-ft. 

2 Includes 22,000 acre-ft estimated from Ruby Lake Marsh. See discussion in text. 

91 to 92 percent of the phreatophyte area was comprised of areas with plant cover less than 20 percent, 

bare soil, playa, or water-covered playa. The area of 

permanent water was insignificant. 

Areas with 20 percent or more plant cover 

accounted for about 36 percent of estimated groundwater evapotranspiration in 1985 and about 27 percent 

in 1989 (table C6). The estimated mean annual rate of 

ground-water evapotranspiration was two to two and a 

half times greater than the rate for these areas used by 

the earlier reconnaissance series of studies in 1985 and 

1989. Areas with less than 20 percent plant cover 

accounted for about 64 percent of estimated groundwater evapotranspiration in 1985 and about 73 percent 

in 1989. The estimated mean annual rate of evapotranspiration was about 0.3 ft in 1985 for those areas with 

less than 10 percent plant cover, similar to the rate used 

by many of the earlier reconnaissance studies, and 

about 1.3 ft for areas of 10-20 percent plant cover in 

1985 (table C6). Estimated rates were similar for 1989. 

Estimated Mean Annual Ground-Water 

Evapotranspiration 

A mean annual value of ground-water evapotranspiration implies a hydrologic steady-state condition. This, in tum, implies no change in ground-water 

storage and no change in interbasin ground-water flow. 

When estimates of annual ground-water evapotranspiration differ from one year to another (table C5), 

changes in ground-water storage, as well as interbasin 

ground-water flow, should be included in any method 

used to estimate long-term mean annual ground-water 

discharge. A rise in ground-water levels over an annual 

cycle indicates an excess of recharge to the valley-fill 

aquifer over discharge from the aquifer, but implies 

nothing about when the recharge occurred in the adjacent mountain block. In this case, recharge may have 

been greater than the long-term mean annual recharge 

or discharge may have been less than the long-term 

mean annual discharge, or more likely a combination 

of both. Similarly, a decline in ground-water levels 

over an annual cycle indicates an excess of discharge 

ESTIMATED GROUND-WATER DISCHARGE AND RECHARGE C15 
Table C6. Summary of area, percent plant cover, mean annual ground-water evapotranspiration (ET) rate, and annual 

ground-water evapotranspiration for indicated land cover for 1985 and 1989 for eastern Nevada study area 1 

[Symbols:<, less than;~. greater than or equal to] 

1985 1989 

Plant Annual Annual Plant Annual Annual 

Land cover Area ET Area ET 

(acres) cover ET rate (acre- (acres) cover ET rate (acre- (percent) (feet) feet) (percent) (feet) feet) 

Water 82,431 650 1,487 650 

Bare soil/playa 162,736 0.150 24,410 122,341 0.150 18,351 

< 10 percent plant cover 728,988 6.0 .290 211,361 804,624 7.1 .410 322,891 

10 - < 20 percent plant cover 171,415 13.7 1.346 230,777 227,276 13.1 1.276 290,003 

20 - < 35 percent plant cover 67,745 25.3 2.144 145,252 58,178 25.6 2.154 125,291 

35 - < 50 percent plant cover 23,980 41.2 2.506 60,103 20,902 40.6 2.504 52,346 

~ 50 percent plant cover 20,697 63.1 2.584 53,485 23,184 62.9 2.582 59,847 

. Total 2 1,258,000 726,000 1,258,000 869,000 

-. Weighted average 3.105 .577 3.110 .690 

1 Calculated values are not rounded, to minimize rounding errors in subsequent calculations, except as indicated. 

2.Totals are rounded to the nearest 1,000 acres and acre-ft. 

3 Does not include areas of bare soil, playa, or areas covered by water. 

over recharge, which may represent discharge greater 

than the Jong-term mean annual discharge or recharge 

less than. the long-term mean annual recharge, or again 

a combiJiation of both. Interannual changes in groundwater levels commonly are a foot or two and as such do 

not significantly increase or decrease water-level gradients, and~consequently ground-water flow rates, in 

areas of interbasin ground-water flow. Annual groundwater evapotranspiration in combination with annual 

ground-water recharge is largely responsible for 

changes in ground-water storage and, therefore, 

changes in ground-water levels. 

Appropriate ground-water level data are sparse in 

the valleys of the study area, and detailed estimates of 

changes i!l ground-water storage were not possible. 

Only Ruby, Clover, and Steptoe Valleys have waterlevel data that provide some insight into changes in 

ground-water storage in 1985 and 1989. Even in these 

valleys, ~owever, data were insufficient to characterize 

the change in storage over the entire valley. While 

including the change in ground-water storage together 

with grol,lnd-water evapotranspiration is an objective 

method for estimating long-term mean annual 

discharge, this method cannot be applied in the present 

study because of the lack of appropriate water -level 

data. Consideration of this method should be given in 

future studies of this type. 

Ground-water evapotranspiration estimated for 

1985 was similar to that estimated for 1989 in Clover, 

Hot Creek, Jakes, Little Smoky, Long, Newark, and 

Railroad Valleys; the average of the 2 years was 

assumed to approximate mean annual ground-water 

evapotranspiration in these valleys. Ground-water 

evapotranspiration estimated for 1989 from Antelope 

and Tippett Valleys exceeded the estimates for 1985, 

but the totals for each year are relatively small; the 

average of the 2 years was assumed to approximate the 

mean annual value for these two valleys as well. Differences between ground-water evapotranspiration estimated for 1985 and 1989 for Ruby, Spring, and Steptoe 

Valleys are substantial, but in the absence of sufficient 

water-level data with which to estimate changes in 

ground-water storage to reconcile the difference, the 

average of the 2 years was assumed to approximate 

mean annual ground-water evapotranspiration. 

Ground-water evapotranspiration estimated for 

1989 from Butte, Goshute, and Independence Valleys 

significantly exceeded that estimated for these valleys 

for 1985. Estimates of mean annual ground-water 

evapotranspiration for these valleys, and for Little Fish 

Lake Valley (table C5), were developed during determination of mean annual recharge estimates discussed 

below. 

C16 Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
The depth to ground water is greater than 100 ft 

beneath Jakes, Tippet, and much of Antelope Valleys. 

Previous studies did not include evapotranspiration 

from the phreatophytes growing in these areas in the 

ground-water budget. Field studies as part of this investigation and elsewhere in Nevada (Nichols, 1994) have 

shown that phreatophytes, even in areas with depths to 

ground water of no more than 20 ft, may subsist on 

perched ground water at shallower depths. Phreatophytes in Tippett Valley and those areas of deep ground 

water in Antelope Valley are assumed to be supported 

by perched ground water, and while this ground water 

cannot be developed, it is water that is a part of the 

ground-water budget. No ground-water evaporation is 

estimated from bare soil or playa areas of these two valleys. Ground-water evapotranspiration in Jakes Valley 

is from phreatophytes in the valley of Illipah Creek, 

which is tributary to Jakes Valley. No ground-water 

evaporation is estimated from the small area of bare 

soil or playa in the main valley. 

The marshes of the Ruby Lake National Wildlife 

Refuge in southern Ruby Valley present a particular 

problem for the approach used in this study. Plant cover 

values for the marsh area are not correct because the 

vegetation index derived from Landsat data is incorrect, although water areas are properly identified. 

Much of the green vegetation in the marsh area during 

mid to late June is obscured or partly obscured from the 

satellite's view by senescent vegetation from the previous year(s). The preponderance of senescent vegetation 

returns reflectance values to the satellite sensor that are 

in the range for bare soil. This was especially true in 

1985 when the plant cover data indicated that about 70 

percent of the marsh was bare soil, when, in fact, bare 

soil probably was not visible in the marsh area because 

of the large area of open water in 1985 from previous 

years of above-normal precipitation. Plant cover data 

for 1989 indicate about 27 percent of the marsh area 

was bare soil; probably about 17 percent of the marsh 

area, limited to the northeastern and eastern border of 

the marsh was bare soil in 1989. 

The marsh area in southern Ruby Valley covers 

about 14,600 acres. In 1985, open water within the 

marsh area covered 3,535 acres. By 1989, after 3 years 

of below-normal precipitation and 1 year of near-normal precipitation, the open water area of the marsh was 

1,030 acres. To estimate evapotranspiration from the 

marsh area, the water area of 1989 is assumed to represent the approximate mean annual area of open water. 

The rest of the marsh area, under mean annual conditions, includes about 11,100 acres of vegetation of all 

types and about 2,500 acres of bare soil, the area along 

the northeastern and eastern borders of the marsh covered by water in 1985. Estimated open-water annual 

evaporation in this area of Nevada is about 4ft (Scott, 

1971) suggesting evaporation from open water of 

about 4,120 acre-ft/yr. Evapotranspiration from marsh 

vegetation may range from 1.5 to 3.5 ft/yr (G.A. 

DeMeo, U.S. Geological Survey, written commun., 

1998); a mean annual estimate of about 2 ft is assumed 

for this analysis and suggests evapotranspiration of 

22,200 acre-ft/yr from all vegetation within the marsh 

area. About 500 acre-ft of ground water may evaporate 

from the bare soil area. Total estimated evapotranspiration from water, vegetation, and bare soil in the 

marsh area is estimated to be about 26,800 acre-ft/yr, 

which includes surface water inflow to the marsh area 

as well as ground water. Estimates are that perhaps 

5,000 acre-ft/yr of this is supported by surface-water 

inflow and that about 22,000 acre-ft/yr is supported by 

ground water. This was added to the ground-water 

evapotranspiration of about 135,000 acre-ft/yr in 1985 

and about 155,000 acre-ft/yr in 1989 estimated from 

plant cover data for the rest of Ruby Valley (tables C5 

and C17). 

Mean annual ground-water evapotranspiration 

estimated by this study is compared with that estimated 

by the reconnaissance series of studies in table C7. The 

present study estimates slightly more than twice as 

much ground-water evapotranspiration from the valleys of the study area than these earlier studies. 

Recharge From Precipitation 

Estimates of ground-water discharge by evapotranspiration from the valleys of the study area provide 

a basis for estimating ground-water recharge from precipitation; any additional discharge from or recharge to 

a valley through interbasin ground-water flow must be 

estimated or known independently. The estimates of 

mean annual ground-water evapotranspiration developed by this study and estimates of regional interbasin 

ground-water flow suggested by previous studies summarized and compiled by Harrill and others (1988) 

were used to determine new estimates of ground-water 

recharge to the valleys of the study area using a map of 

annual precipitation in Nevada for 1961-90. 

ESTIMATED GROUND-WATER DISCHARGE AND RECHARGE C17 
Table C7~ Comparison of estimated mean annual groundwater evapotranspiration for eastern Nevada study area, 

from reconnaissance studies and from this study 

Yalley 

Mean annual ground-water 

evapotranspiration (acre-feet} 

Reconnaissance This study 1 

studies 

Antelope Valley 100 4,000 

Butte Valley 19,900 44,500 

Clover Valley 19,000 84,500 

Goshute Yalley 2 10,075 42,500 

Hot Creek Valley 4,600 5,000 

Independence Valley 9,500 47,000 

Jakes Vai_iey 600 

Little Fish Lake Valley 10,000 9,700 

Little Srrtoky Valley 1,900 6,000 

Long Valley 2,200 11,000 

Newark Valley 16,000 60,500 

Railroad ·yalley 

(northern part) 3 80,000 85,000 

Ruby Vai}ey 67,600 167,000 

Spring Valley 70,000 90,000 

Steptoe Valley 70,000 128,000 

Tippett Valley 0 2,900 

·.Total 1

381,000 788,000 

1 Nu~bers are rounded to the nearest 100 acre-ft for values less than 

10,000 acre-ft, to the nearest 500 acre-ft for values equal to or greater than 

10,000 acre-ft and less than 100,000 acre-ft, and to the nearest 1,000 acreft for values equal to or greater than 100,000 acre-ft. 

2 Reconnaissance estimate includes estimate for Antelope Valley. 

3 VanDenburgh and Rush (1974). 

Regional Precipitation 

Regional precipitation is difficult to characterize 

for simple terrain conditions, but those difficulties are 

compounded by orographic effects of the complex terrain of the intermountain west including Nevada and 

the Great Basin. Multiple storm tracks and rainshadow 

effects preclude a simple relation between precipitation 

and local altitude. The western and southern parts of 

the study area, including Newark, Little Fish Lake, Little Smoky, Hot Creek, and Railroad Valleys, are influenced by a westerly winter storm track, but lie in the 

rainshadow of the Sierra Nevada in western Nevada 

and eastern California, and the Toiyabe Range in central Nevada (fig. C1). The northern and eastern part of 

the study area is affected, to a greater extent, by a northwesterly storm track. Storms moving southwest over 

the low terrain of southern Idaho and north-central 

Nevada do not reach high-altitude topography until the 

Ruby Mountains and East Humboldt Ranges that form 

the northwestern border of the study area. These 

ranges, consequently, receive significantly greater precipitation than most other mountain ranges in Nevada. 

The rainshadow effects of the Ruby Mountains and the 

Toiyabe Range can be seen in the precipitation record 

(table C8) for ranges from the Ruby mountains to the 

southeast (pl. 1). The precipitation-altitude relation 

demonstrated by these data (fig. C4) is significantly 

different over most of the study area from the relation 

assumed by the reconnaissance studies. 

A model for estimating and distributing annual 

average precipitation at a regional scale that is well 

suited to areas with mountainous terrain has recently 

been developed (Daly and others, 1994). The model, 

known by the acronym PRISM (Precipitation-elevation 

Regression on Independent Slopes Model), was used to 

generate a map of estimated annual precipitation for 

Nevada for 1961-90 (G.H. Taylor, Oregon State University, written commun., May 21, 1997). The annual 

precipitation estimates on this map were used, in this 

study, to estimate ground-water recharge to the eastern 

Nevada study area. 

Annual precipitation in the valleys of the study 

area estimated by the PRISM model is compared in 

table C9 to that estimated from the Hardman ( 1936) 

map and used by the earlier reconnaissance studies. 

Precipitation estimated from the PRISM data exceeds 

that estimated from the Hardman map for the reconnaissance studies. Increases ranged from 101 percent 

greater than the Hardman map estimate in Steptoe Valley to 141 percent greater in Antelope Valley. For estimating recharge, a more significant comparison is of 

precipitation in areas that receive annual precipitation 

greater than 20 inches. The area, volume, and estimated 

average precipitation greater than 20 inches from the 

reconnaissance studies and the area, volume, and 

weighted average of precipitation calculated from the 

PRISM data are given in table ClO. Significantly more 

precipitation is estimated by PRISM in the greaterthan-20-inch zone for Butte, Clover, Independence, 

Newark, Railroad, Ruby, Spring, and Steptoe Valleys 

than was estimated by the reconnaissance studies. The 

increase in volume ranged from about 200 to 300 percent for most of the valleys to more than a 1,000 percent increase in Butte and Newark Valleys. 

C18 Chapter C. Regional Ground-Water Budgets and Ground-W!lter Flow, Eastern Nevada 
Table C8. Precipitation at selected SNOTEL stations in eastern 

Nevada, 1961-90 (Greenlee, 1992) 

UJ 

w 

J: 

0 

~ 

~ 

z 

0 

40 

30 

~ 1- 20 

a: 

0 

w 

a: 

ll. 

...J 

c:( 

::::::1 

~ 10 

c:( 

Station name 1 Mountain range 

Lamoille #3 Ruby Mountains 

Hole-In-Mountain East Humboldt Range 

Green Mountain Ruby Mountains 

Dorsey Basin Ruby Mountains 

Corral Canyon Ruby Mountains 

Diamond Peak Diamond Mountains 

Berry Creek Schell Creek Range 

Ward Mountain Egan Range 

1 Locations are shown on plate 1. 

X SNOTEL stations (table C8) 

+Valley stations (table C2) 

• Reconnaissance studies 

Altitude Mean 

(feet above annual 

precipitation sea level) (inches) 

7,700 33.9 

7,900 33.6 

8,000 32.9 

8,100 31.9 

8,500 29.8 

8,000 24.6 

9,100 26.0 

9,200 24.7 

xx 

X 

0 L-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 

4,000 5,000 6,000 7,000 8,000 9,000 10,000 

ALTITUDE, IN FEET ABOVE SEA LEVEL 

Figure C4. Precipitation-altitude relation, eastern Nevada. 

The May 1997 version of the PRISM map of 

mean annual precipitation of Nevada for 1961-90 was 

used to estimate precipitation in the valleys of the study 

area. One version of this map portrays precipitation 

amounts in 1-inch contour intervals from 4 to 22 

inches, 2-inch intervals from 22 to 26 inches, 4-inch 

intervals from 26 to 42 inches, and 2-inch intervals for 

greater than 42 inches. A second version uses 2-inch 

contour intervals from 4 to 20 inches and a 4-inch contour interval for greater than 20 inches. These data were 

used to create a map using 1-inch contour intervals 

over the entire range of precipitation values. 

Determination of Recharge Coefficients 

The areas and volumes corresponding to l-inch 

increments of mean annual precipitation were determined for each valley of the study area (table C 18 at the 

end of this chapter), which then were combined into 

larger intervals for use in recharge calculations. Following Maxey and Eakin ( 1949) and Eakin and others 

( 1951 b), no recharge was assumed from precipitation 

of less than 8 inches. The remaining precipitation zones 

were combined into the following intervals: 8 to less 

than 12 inches, 12 to less than 16 inches, 16 to less than 

20 inches, 20 to less than 34 inches, and equal to or 

ESTIMATED GROUND-WATER DISCHARGE AND RECHARGE C19 
Table C9. Area and annual volume of precipitation estimated by reconnaissance studies 

and by present study for valleys in eastern Nevada study area 1 

[Area is in acres and volume of precipitation is in acre-feet per year. Symbol: --,not reported.] 

Reconnaissance studies This study (PRISM) 

Valley 

Area Precipitation Area Precipitation 

Antelope Valley 252,600 175,200 255,680 246,551 

Butte Valley 635,400 563,300 652,362 700,905 

Clover Valley 288,100 287,870 292,115 363,328 

Goshute Valley 612,168 592,875 

Hot Creek Valley 657,990 397,340 658,500 424,067 

Independence Valley 336,000 296,280 360,670 394,414 

Jakes Valley 270,498 289,477 

Little Fish Lake Valley 278,260 226,750 276,483 236,430 

Little Smoky Valley 743,840 432,930 740,576 523,359 

Long Valley 416,000 343,940 419,844 452,367 

Newark Valley 512,000 410,490 509,283 515,471 

Railroad Valley 

(northern part) 1,376,800 996,000 1,369,671 1,089,249 

Ruby Valley 639,900 682,550 638,935 867,225 

Spring Valley 1,084,900 962,790 1,067,010 1,141,444 

Steptoe Valley 1,265,000 1,328,310 1,245,618 1,344,191 

Tippett Valley 233,000 164,500 221,574 211,905 

1 Calculated values are not rounded, to minimize rounding errors in subsequent calculations. 

Table C1 0. Comparison of area, average annual rate, and annual volume of precipitation greater 

than 20 inches estimated by reconnaissance studies and equal to or greater than 20 inches estimated 

by the present study for valleys in eastern Nevada study area 

[Area is in acres, mean precipitation is in inches per year, and volume is in acre-feet per year.] 

Reconnaissance studies Present study 

Valley Area, Mean Area, Weighted mean Volume1 

>20inches precipitation Volume :?:20 inches 1 precipitation 

Antelope Valley 0 0 520 20.0 867 

Butte Valley 4,300 21.6 7,740 42,607 22.4 79,414 

Clover Valley 15,600 25.0 32,448 38,542 26.7 85,764 

Goshute Valley. 0 0 5,584 20.8 9,675 

Hot Creek Valley 0 0 570 20.0 950 

Independence Valley 0 0 9,251 20.7 15,970 

Jakes Valley 0 0 607 20.0 1,011 

Little Fish Lake Valley 2,390 21.0 4,183 0 0 

Little Smoky Valley 0 0 3,407 20.0 5,678 

Long Valley 0 0 5,604 21.5 10,050 

Newark Valley 3,000 21.0 5,250 30,283 22.1 56,210 

Railroad Valley 

(northern part) 22,000 21.6 39,600 48,281 22.3 89,567 

Ruby Valley 58,900 25.0 122,512 109,401 26.9 244,863 

Spring Valley 59,100 21.0 103,425 96,091 24.3 194,247 

Steptoe Valley 57,000 21.0 99,750 120,169 23.6 236,437 

Tippett Valley 280 21.6 504 958 20.0 1,596 

1 Calculated values are not rounded, to minimize rounding errors in subsequent calculations. 

C20 Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
greater than 34 inches. These intervals were decided 

upon after solving for recharge coefficients, or percentages, using several combinations of intervals and are 

similar to those used by Maxey and Eakin (1949) and 

Eakin and others ( 1951 b) with the exception of the 

zone with precipitation greater than 34 inches. 

Two criteria were used in determining recharge coefficients, or percentages: 

1. No coefficient was assumed to be less than 0 

because a negative percentage has no physical 

meaning, and 

2. The coefficients, or percentage of recharge, 

should increase from the smallest value for the 

8-to-less-than-12-inch zone to the largest value 

for the equal-to-or-greater-than-34-inch zone. 

With the volume of precipitation for each precipitation zone and an estimate of ground-water recharge 

from precipitation based on the estimated ground-water 

discharge, the following multiple-linear regression 

model can be solved (see also Watson and others, 

1976): 

5 

Y = b0 + ~ b .x. + E. £..- l l l (1) 

n = 1 

where Yis the estimated recharge, in acre-feet, based 

on the estimated discharge, in acre-feet; 

X; is the independent variable, in this case precipitation volume, in acre-feet, in each of the 

five precipitation zones; 

bi is the coefficient for each independent variable; 

b0 is the intercept, in acre-feet, on the Yaxis; and 

Ei is the error, in acre-feet, in the estimated discharge. 

Estimated ground-water discharge by evapotranspiration must be corrected for any interbasin flow into 

or from the basin to reflect the total recharge needed to 

maintain steady-state equilibrium of the ground-water 

system in the valley. Correctly defining recharge and 

discharge is further complicated by the assumption that 

the hydrologic basin is coincident with the topographic 

basin; that is, hydrologic divides are defined by topographic divides. The exact locations of ground-water 

divides in the study area are not known, and in the fractured and faulted carbonate-rock terrain of eastern 

Nevada these divides may be substantially displaced 

from topographic divides. The present study followed 

conventional practice and assumed that the hydrologic 

basin is coincident with the topographic basin; any contribution to or loss from another topographic basin was 

assumed to occur as interbasin ground-water flow. 

Estimated ground-water discharge by evapotranspiration was modified by adding or subtracting estimated interbasin ground-water flow suggested by 

previous studies (summarized by Harrill and others, 

1988) and by analysis of the distribution and location 

of ground-water evapotranspiration estimated by this 

study. Application of the estimated magnitude of interbasin flow summarized by Harrill and others (1988) is 

problematic, because these magnitudes are based on 

the reconnaissance estimates of ground-water discharge and recharge. However, the locations and directions of interbasin flow (fig. C5) given by Harrill and 

others ( 1988) provide a framework within which to 

determine new estimates of the magnitude of interbasin 

flow. 

Analysis of the distribution of ground-water 

evapotranspiration estimated by the present study provides additional information about the magnitude of 

interbasin flow for several valleys. Previous studies 

have suggested that ground water discharged by 

springs near Duckwater and near Lockes in Railroad 

Valley (pl. 1) represents interbasin flow from adjacent 

valleys (Rush and Everett, 1966; Van Denburgh and 

Rush, 1974; Prudic and others, 1995). The present 

study estimated ground-water evapotranspiration of 

12,500 acre-ft/yr in the Duckwater area and as much as 

9,000 acre-ft/yr in the Lockes area (Chapter B, table 

B2) suggesting that as much as 21,500 acre-ft/yr of 

ground-water evapotranspiration in Railroad Valley 

may not be derived from recharge by precipitation in 

the valley. 

Interbasin flow to Newark Valley from Long and 

Little Smoky Valleys has been suggested previously by 

Harrill and others (1988). Examination of the phreatophyte plant cover distribution (pis. 2 and 3) suggests 

that the phreatophytes covering about 2,200 acres in 

southwestern Newark Valley probably are related to 

interbasin flow derived from spring discharge at Fish 

Creek Springs (pl. 1) in Little Smoky Valley. The large 

area of phreatophytes in northeastern Newark Valley 

(pis. 2 and 3), in the area of Warm Springs Ranch (pl. 

1 ), may well be supported by ground water moving 

from Long Valley through the thick sequence of Devonian carbonate rocks underlying the mountains to the 

east; between 2,500 and 6,500 acres of phreatophytes 

ESTIMATED GROUND-WATER DISCHARGE AND RECHARGE C21 
EXPLANATION 

1 0? r=> lnterbasin ground-water flow-Arrow 

indicates direction. Number indicates 

magnitude, in thousands of acre-feet. 

Queried where occurrence and 

magnitude are inferred 

M r=> Minor interbasin flow-Less than 

1,000 acre-feet 

0 

I 

0 

50 MILES I I 

50 KILOMETERS 

Figure CS. Directions, locations, and estimated magnitude of interbasin ground-water flow in eastern Nevada as 

suggested by earlier studies; from Harrill and others (1988) except northward inflow· to northern part of Railroad 

Valley, which is from Van Denburgh and Rush (1974). Directions, locations, and estimated magnitude of interbasin ground-water flow in eastern Nevada based on the results of the present study are shown on plate 4. 

C22 Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
may be supported by this interbasin flow. Similarly, as 

much as 8,500 acres of phreatophytes in the southeastern phreatophyte area in central Newark Valley south 

of Buck Mountain (pls. 2 and 3) may be supported by 

interbasin flow from Long Valley through the upper 

Paleozoic carbonate rocks and Tertiary volcanic rocks 

underlying the mountains to the east of Newark Valley 

in this area. Estimated ground-water evapotranspiration from these areas, from the present analysis, is 

about 1,500 acre-ft/yr in southeastern Newark Valley, 

from about 5,000 to about 9,000 acre-ft/yr from the 

Warm Springs Ranch area, depending on the size of 

the area supported by interbasin flow, and as much as 

6,000 acre-ft/yr from the southeastern phreatophyte 

area south of Buck Mountain, again depending on the 

area supported by interbasin flow. This suggests that 

as much as 16,500 acre-ft/yr of ground-water evapotranspiration in Newark Valley may be derived from 

recharge from precipitation outside the topographic 

limits of the valley. 

The multiple linear regression model (eq. 1) was 

used to derive new coefficients, or percentages, by 

which to estimate ground-water recharge from precipitation. Ground-water evapotranspiration from each valley estimated by the present study (table C7) and 

modified by interbasin ground-water flow estimated by 

this study or by previous studies, as summarized by 

Harrill and others (1988), were used in the model as the 

initial estimates of ground-water recharge from precipitation to each basin. Ground-water evapotranspiration 

for each valley and estimated values of probable and 

proposed net interbasin ground-water flow are given in 

table C11. 

Probable values of predicted interbasin flow are 

based on hydrologic measurements, such as spring 

discharge, or on ground-water evapotranspiration 

Table C11. Estimated and predicted ground-water evapotranspiration and interbasin ground-water flow for predicting groundwater recharge to valleys in eastern Nevada study area 1 . 

[All values in acre-feet per year] 

Net interbasin Predicted Predicted Ground- Difference 

Ground- ground-water flow 2 

Estimated ground- total water Predicted between 

water evapo- total ground- water ground- evapotrans- net inter- predicted pi ration basin flow 

Valley transpiration From For water discharge recharge water adjusted from recharge 

from this previous regression for regression from discharge from and 

study: Initial studies analysis, analysis regression from regression f t d 

regression analysis2 e~ lma e estimate (fig. CS) this study (A+ C) analysis, regression analysis (E _ G) discharge 

equation 1 analysis (table CS) (E-D) 

A B c D E F G H 

Antelope Valley 4,000 +5,000 +12,000 16,000 16,872 16,872 4,000 +12,872 +872 

Butte Valley 47,000 +1,000 +23,500 70,500 69,122 69,122 44,500 +24,622 -1,378 

Clover Valley 84,500 0 -25,400 59,100 58,872 58,872 84,500 -25,628 -228 

Goshute Valley 42,500 +2,000 -1,500 41,000 41,026 41,026 42,500 -1,474 +26 

Hot Creek Valley 5,000 +11,000 +800 5,800 5,806 5,806 5,000 +806 +6 

Independence Valley 48,000 0 +2,200 50,200 50,142 50,142 47,000 +3,142 -58 

Jakes Valley 600 +17,000 +17,000 17,600 38,259 38,259 600 +37,659 +20,659 

Little Fish Lake Valley 9,600 0 0 -9,600 9,674 9,674 9,700 -26 +74 

Little Smoky Valley 6,000 +3,000 +5,500 11,500 12,753 12,753 6,000 +6,753 +1,253 

Long Valley 11,000 +8,000 +27,000 38,000 47,826 47,826 11,000 +36,826 +9,826 

Newark Valley 60,500 -1,000 -8,500 52,000 49,189 49,189 60,500 -11,311 -2,811 

Railroad Valley 

(northern part) 85,000 -17,000 -18,000 67,000 61,234 61,234 85,000 -23,766 -5,766 

Ruby Valley 148,000 -11,000 0 148,000 145,795 145,795 167,000 -21,205 -2,205 

Spring Valley 90,000 +2,000 +4,000 94,000 103,777 103,777 90,000 +13,777 +9,777 

Steptoe Valley 127,500 0 +2,000 129,500 131,716 131,716 128,000 +3,716 +2,216 

Tippett Valley 2,900 +7,000 +9,000 11,900 12,430 . 12,430 2,900 +9,530 +530 

Total 772,100 +27,000 +49,600 821,700 854,493 854,493 788,200 +66,293 +32,793 

1 Calculated values are not rounded, to minimize rounding errors in subsequent calculations. 

2 Positive value is estimated net flow from indicated basin. Negative value is estimated net flow into indicated basin. 

ESTIMATED GROUND-WATER DISCHARGE AND RECHARGE C23 
estimated by the present study, such as those described 

for Railroad and Newark Valleys; these are described 

more fully in the following section. Proposed values of 

predicted interbasin ground-water flow are not demonstrated by direct hydrologic measurement. They are, 

however, supported by geologic and hydrologic conditions that are described more fully in the following 

section. The model then was calibrated by increasing 

or decreasing estimated interbasin flow, where necessary, for predicted recharge to equal estimated discharge for each basin, while also meeting the two 

criteria given above. 

Data for 14 of 16 basins were used to solve the 

multiple linear regression model (eq. 1); Jakes Valley 

was excluded from the analysis because essentially no 

ground water evapotranspired from the valley. Data for 

Goshute Valley were excluded during preliminary calibration of the model because of the large difference 

between the 1985 and 1989 estimated ground-water 

evapotranspiration. Initial solutions of the model suggested recharge to Goshute Valley of about 41,000 

acre-ft/yr. An estimated ground-water evapotranspiration of 42,500 acre-ft/yr was selected to be consistent 

with a balanced ground-water budget that also accommodated previous estimates of interbasin flow (Harrill 

and others, 1988) and excess recharge to Steptoe Valley estimated by the present study. The data for Clover, 

Independence, and Butte Valleys were combined and 

treated as data for a single valley for initial model calibration. Data for each valley separately were used for 

final model calibration. Estimated mean annual 

ground-water evapotranspiration for Independence and 

Butte Valleys were determined so as to allow sufficient 

interbasin flow to satisfy ground-water evapotranspiration from Clover Valley. The predicted interbasin 

flows are consistent with hydrologic conditions as discussed below. 

The coefficients, or percentages, by which to multiply precipitation in each precipitation zone are given 

in table C12. They-axis intercept, b0, for equation 1 

was 8.7; setting b0 to zero leads to no change in the 

coefficients. Statistics for the regression model are not 

valid because it was calibrated so that estimated 

recharge equaled total estimated discharge for each 

valley and the solution therefore has an r

2 = 1.0 (table 

C11). However, simple linear regression of estimated 

discharge (Column D, table C11) against predicted 

recharge (Column E, table C11) yields an r

2 of 0.975 

and an adjusted~ of 0.909. 

Table C12. Coefficients for estimating recharge from 

precipitation in eastern Nevada study area 

Precipitation zone 

(inches) 

8 to less than 12 

12 to less than 16 

16 to less than 20 

20 to less than 34 

equal to or greater than 34 

Estimated Recharge 

Coefficient 

0.008 

.130 

.144 

.158 

.626 

The coefficients (table C12) calculated with equation 1 were used to compute estimated ground-water 

recharge from each precipitation zone in each valley of 

the study area (table C19 at the end of this chapter). The 

results are summarized and compared with groundwater recharge estimated by the reconnaissance studies 

in table C13. The present study estimates a little more 

than twice as much recharge from precipitation as was 

· estimated by these earlier studies. The largest percentage changes in estimated recharge were in Antelope, 

Butte, Goshute, Independence, and Long Valleys, all 

with present estimates more than 300 percent of the 

reconnaissance study estimates. Estimates of recharge 

increased between 200 and 300 percent in Clover, 

Jakes, Little Smoky, Newark, and Ruby Valleys. 

Increases in estimated recharge to Railroad, Spring, 

Steptoe, and Tippett Valleys were less than 200 percent 

greater than the reconnaissance estimates. Estimated 

recharge to Little Fish Lake Valley and Hot Creek Valley was about 10 to 20 percent less than that estimated 

by the reconnaissance study for these valleys. 

ESTIMATED GROUND-WATER BUDGETS 

AND REGIONAL FLOW 

Estimated ground-water evapotranspiration for 

each valley of the study area given in table C7 and the 

estimated recharge from precipitation given in table 

C13 were used to develop ground-water budgets for the 

eastern Nevada study area. The estimates of groundwater evapotranspiration apply specifically and completely to the valley for which the estimate was made. 

The estimated ground-water recharge applies to 

the topographic basin of a given valley which is 

not necessarily coincident with the hydrologic basin. 

Additionally, the estimated recharge is a bulk estimate 

that only indirectly implies where the recharge occurs 

C24 Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
Table C13. Annual ground-water recharge from precipitation 

estimated by reconnaissance studies and by present study 

for valleys of eastern Nevada study area 

Valley 

Antelope Valley 

Butte Valley 

Clover Valley 

Goshute Valley 

Hot Creek Valley 

Independence Valley 

Jakes Valley 

Little Fish Lake Valley 

Little Smoky Valley 

Long Valley 

Newark Valley 

Railroad Valley 

(northern part) 

Ruby Valley 

Spring Valley 

Steptoe Valley 

Tippett Valley 

Total 

Annual ground-water recharge 

(acre-feet) 

Reconnaissance This study 1 

study 

4,700 17,000 

19,000 69,000 

20,700 59,000 210,400 41,000 

7,000 5,800 

9,300 50,000 

17,000 38,500 

11,000 9,700 

5,400 13,000 

10,300 48,000 

17,500 49,000 

46,000 61,000 

68,000 146,000 

75,000 104,000 

85,000 132,000 

6,900 12,500 

1

413,000 855,000 

1 Numbers are rounded to the nearest 100 acre-ft for values less than 

10,000 acre-ft, to the nearest 500 acre-ft for values equal to or greater than 

10,000 acre-ft and less than 100,000 acre-ft. and to the nearest 1,000 acre-ft 

for values equal to or greater than 100,000 acre-ft. 

2 Includes recharge estimate for northern Antelope Valley. 

within the basin, the assumption being that the 

most recharge occurs in that part of the valley where 

the most precipitation occurs. Any excess of recharge 

from precipitation over ground-water evapotranspiration in a given topographic basin is assumed to be discharged from that valley as interbasin flow to adjacent 

valleys if interbasin flow was proposed by earlier studies or can be supported by available geologic and 

hydrologic conditions, or represents recharge directly 

to part of a hydrologic basin that is not coincident with 

the topographic basin. Similarly, any deficiency in 

recharge from precipitation is assumed to be compensated by interbasin flow into the valley, or by modifying the topographic basin boundary to include the area 

of the hydrologic basin to which the recharge occurs. 

Consequently, any errors in the estimates of groundwater evapotranspiration and recharge are included in 

the estimates of interbasin ground-water flow. 

Harrill and Prudic (1998) identified 287 hydrographic areas in the Great Basin, some of which are 

divided into from 2 to 4 subareas. These areas and 

subareas are delineated by topography around and 

within the valleys for which the areas and subareas 

were defined; that is, topographic basins and hydro-

- logic areas were assumed to be coincident. Regional 

ground-water flow systems in the Great Basin have 

been delineated by Harrill and others (1988). A simulation analysis of regional ground-water flow in the carbonate-rock province of the central and eastern Great 

Basin, including the present study area, delineated subregional flow-system boundaries on the basis of estimated horizontal ground-water flow and was not 

constrained by topographic and hydrographic boundaries (Prudic and others, 1995, p. D53). These flow systems are similar, but not identical, to those proposed by 

Harrill and others (1988). 

The results of the present study are consistent 

with, and tend to corroborate, most of the boundaries 

previously defined by Harrill and others (i988). To the 

extent possible, previously delineated regional and 

subregional flow system names and boundaries of Harrill and others (1988) are retained in the present analysis. Where warranted by the results of the present 

study, however, flow-system boundaries have been 

revised. The results of the present study suggest the 

valleys of the study area may be grouped into the following regional flow systems (pl. 4): 

• Newark Valley system -

Newark Valley 

Little Smoky Valley 

Northern part 

Central part 

• Railroad Valley systemLittle Fish Lake Valley 

Little Smoky Valley 

Southern part 

Hot Creek Valley 

Railroad Valley 

Northern part 

• Independence Valley system -

Clover Valley 

Independence Valley 

Butte Valley 

• Ruby Valley system -

Ruby V(l.lley 

• Colorado system -

Long Valley 

Jakes Valley 

ESTIMATED GROUND-WATER BUDGETS AND REGIONAL FLOW C25 
• Goshute Valley system -

Goshute Valley 

Steptoe Valley 

• Great Salt Lake Desert system -

Spring Valley 

Tippett Valley 

Antelope Valley 

The Newark and Railroad Valley ground-water 

flow systems are the same as delineated by Harrill and 

others (1988). Northern Butte Valley was included in 

the Ruby Valley system by Harrill and others (1988), 

but is included in the Independence Valley system in 

the present study. Southern Butte Valley was included 

in the Goshute Valley system by Harrill and others 

( 1988), but is included in the Independence Valley system in the present stuc)y, although it is possible that the 

southern one-third of Butte Valley is an isolated subarea that is not connected hydrologically to any adjacent area. 

Newark Valley System 

The Newark Valley flow system includes Newark 

Valley and the northern and central parts of Little 

Smoky Valley to the southwest (pl. 4) and covers the 

same area proposed by Harrill and others (1988). 

Annual ground-water discharge by evapotranspiration 

from Newark Valley was estimated to be about 60,500 

acre-ft/yr (tables C7 and C15), which includes from 

5,000 to 9,000 acre-ft/yr of evapotranspiration associated with spring discharge in the area of Warm Springs 

Ranch in northeastern Newark Valley, as much as 

6,000 acre-ft/yr from the area south of Buck Mountain, 

and about 1,500 acre-ft/yr of evapotranspiration from 

the Fish Creek area in southwestern Newark Valley. 

Ground-water recharge from precipitation on Newark 

Valley was estimated to be about 49,000 acre-ft/yr 

(tables C13 and C15). This suggests an imbalance of 

about 11,500 acre-ft/yr. The estimated ground-water 

evapotranspiration and estimated recharge are substantially greater than the 16,000 acre-ft/yr for each estimated by Eakin (1960). 

The distribution of ground-water evapotranspiration in Newark Valley, as indicated by the distribution 

of plant cover shown on plates 2 and 3, suggests 

sources of recharge, other than precipitation, to the valley. Ground-water evapotranspiration along the northwestern part of the valley obviously is supported by 

recharge in the Diamond Mountains (pl. 1 ), while that 

along the east side of Newark Lake appears to be 

derived from recharge to Buck Mountain (pl. 1). The 

estimated ground-water evapotranspiration of 5,000-

9,000 acre-ft/yr in the northeast end of the valley, near 

Warm Springs Ranch (pl. 1), probably is supported by 

interbasin flow from Long Valley to the east, although 

some interbasin flow into northern Newark Valley may 

come from Huntington Valley to the north. The mountains immediately east of Warm Springs Ranch are 

underlain by Devonian limestones of the Nevada and 

Devils Gate formations (Hose and Blake, 1976), which 

were described as having significant transmissivity by 

Dudley ( 1967) in the southern Ruby Mountains 20 mi 

to the north. These formations are part of the lower carbonate aquifer of Winograd and Thordarson (1975) in 

southern Nevada (fig. C2). An estimated hydraulic gradient of about 200 ft over a distance of about 10 mi 

(Thomas and others, 1986) and an estimated effective 

width of ground-water flow of about 25,000 ft underlain by the limestones requires a transmissivity of about 

6,000 ft2/d to yield a flow of 5,000 acre-ft/yr. This suggests a hydraulic conductivity of 6-30 ft/d, well within 

the range reported by Winograd and Thordarson 

(1975). The possibility of inflow from Huntington Valley is suggested by sparse water-level data. The presence of a large gravity low beneath the north end of 

Newark Valley and the south end of Huntington Valley 

(Ponce, 1992) suggests the possibility of thick basinfill deposits beneath the topographic divide between 

the two valleys. 

Much of the ground-water evapotranspiration 

from the phreatophyte area in east-central Newark Valley, south of Buck Mountain, represents an additional 

estimated 5,000 acre-ft/yr of interbasin flow from Long 

Valley. The low mountains east of this part of Newark 

Valley are underlain by the Riepe Spring Limestone 

and Arcturas Formation, of Pennsylvanian-Permian 

age and generally equivalent to the upper carbonate 

aquifer of Winograd and Thordarson (1975) in southem Nevada (fig. C2), and by Tertiary volcanic rocks 

and small areas of alluvium (Hose and Blake, 1976). 

An estimated hydraulic gradient of about 200 ft over a 

distance of about 8 mi (Thomas and others, 1986) and 

an effective width of as much as 60,000 ft through 

which ground water may flow requires an average 

transmissivity of only about 2,600 ft2

/d. This suggests 

an average hydraulic conductivity of about 2-26 ft/d, 

depending on aquifer thickness. These values are well 

within the range of hydraulic conductivities reported 

by Winograd and Thordarson (1975) and Plume (1996) 

for the rock types involved. The total interbasin flow 

C26 Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
from the Long Valley topographic basin to Newark 

Valley was estimated to be about 10,000 acre-ft/yr 

(table C14, pl. 4). 

The estimated 1,500 acre-ft/yr of evapotranspiration from the Fish Creek area is believed to be supported by interbasin flow beneath the Fish Creek 

drainage from Little Smoky Valley (pl. 1 ). Any water 

that occurs in Newark Lake is derived from surface 

water runoff and is not part of the ground-water budget. 

The total estimated interbasin flow to Newark Valley 

from Long and Little Smoky Valleys satisfies the 

imbalance in Newark Valley. 

Annual ground-water discharge by evapotranspiration from Little Smoky Valley was estimated to be 

about 6,000 acre-ft/yr (tables C7 and C15), all from the 

northern part of the valley, as compared to 1,900 acreft/yr estimated by Rush and Everett (1966). Annual 

recharge from precipitation was estimated to be about 

13,000 acre-ft/yr (tables C13 and C15); Rush and Everett (1966) estimated 5,400 acre-ft/yr. Of the 7,000 acreft/yr of excess recharge to the entire valley (table C14), 

1,500 acre-ft/yr was estimated to move out of the basin 

as interbasin flow to Newark Valley beneath the Fish 

Creek drainage. The remaining 5,500 acre-ft/yr may 

leave the southern part of the Valley as interbasin flow 

to the Lockes area of Railroad Valley, including about 

2,500 acre-ft/yr as spring discharge near Lockes. 

Railroad Valley System 

The Railroad Valley flow system includes Little 

Fish Lake Valley, the southern part of Little Smoky 

Valley, Hot Creek Valley, and the northern part of 

Railroad Valley (pl. 4 ), .and covers the same area proposed by Harrill and others (1988). Estimated recharge 

to and ground-water evapotranspiration from Little 

Fish Lake Valley, including about 600 acre-ft/yr of 

evaporation from Little Fish Lake, are balanced at 

about 9,700 acre-ft/yr (tables C7, C13, and C15). Rush 

and Everett ( 1966) estimated recharge of 11,000 acreft/yr and discharge of 10,000 acre-ft/yr for Little Fish 

Lake Valley. Annual recharge to Hot Creek Valley was 

estimated by the present study to be about 5,800 acreft/yr (tables C13 and C15), slightly less than the 7,000 

acre-ft/yr estimated by Rush and Everett (1966). 

Ground-water discharge by evapotranspiration in Hot 

Creek Valley was estimated by the present study to be 

about 5,000 acre-ft/yr (tables C7 and C15), 600 acreft/yr more than was estimated by Rush and Everett 

(1966). The balance of 800 acre-ft/yr is believed to 

discharge to northern Railroad Valley from the Twin 

Springs Ranch area (pl. 1) in southeastern Hot Creek 

Valley (pl. 4, table C14). Ground-water discharge by 

evapotranspiration from northern Railroad Valley was 

estimated by the present study to be 85,000 acre-ft/yr 

(tables C7 and C15), which includes about 50 acre-ft/yr 

of evaporation from open water estimated to be supplied by ground water. VanDenburgh and Rush (1974) 

estimated ground-water evapotranspiration from northem Railroad Valley to be about 80,000 acre-ft/yr. 

Ground-water recharge from precipitation is estimated 

to be about 61,000 acre-ft/yr (tables C13 and C15), 

about 30 percent more than the 46,000 acre-ft/yr estimated by Eakin and others ( 1951 b) and Van Den burgh 

and Rush (1974). 

The northern part of Railroad Valley receives 

additional recharge in the form of interbasin flow (table 

C14, pl. 4): about 800 acre-ft/yr from the Twin Springs 

Ranch area of Hot Creek Valley; about 5,500 acre-ft/yr 

from the southern part of Little Smoky Valley that is 

discharged near Lockes in Railroad Valley; about 

13,000 acre-ft/yr that is discharged near Duckwater 

in northwestern Railroad Valley (Chapter B of this 

report); and about 4,000 acre-ft/yr of northward 

flow from the southern part of Railroad Valley (Van 

Denburgh and Rush, 1974, p. 25). 

The spring discharge at Duckwater is believed to 

be derived from deep interbasin ground-water flow 

from Long Valley to the northeast. Van Denburgh and 

Rush ( 197 4) suggested the spring discharge at Duckwater entered Railroad Valley from adjacent, but as yet 

unidentified, valleys. Mifflin (1968) provided 

geochemical evidence that water discharging at Duckwater springs is related to regional ground-water flow 

systems and therefore originates from outside Railroad 

Valley. Harrill and others (1988) suggest interbasin 

flow southward from Newark Valley toward the Duckwater area. Prudic and others (1995) suggested that 

deep interbasin ground-water flow occurs along a zone 

of high transmissivity extending from northern Long 

Valley through eastern Newark Valley to the Duckwater area of Railroad Valley and perhaps continuing 

south. The present study suggests that Long Valley is 

the ultimate source of spring discharge in the Duckwater area because of the excess of recharge over groundwater evapotranspiration in Long Valley, although this 

interbasin flow probably moves beneath Newark Valley. Previous studies were unable to arrive at any conclusions regarding the source of this discharge because 

the reconnaissance ground-water budgets for Newark 

and Long Valleys were substantially balanced with no 

excess recharge available to allocate to interbasin flow. 

ESTIMATED GROUND-WATER BUDGETS AND REGIONAL FLOW C27 
Table C14. Estimated distribution of interbasin ground-water flow for valleys in eastern Nevada study area 

[All values are in acre-feet per year] 

Valley lnterbasin flow from lnterbasin Total lnterbasin flow to lnterbasin Total flow flow 

Antelope Valley Goshute Valley 500 Great Salt Lake Desert 13,500 

500 13,500 

Butte Valley Clover Valley 22,500 

Ruby Valley 2,000 

24,500 

Clover Valley Butte Valley 22,500 

Independence Valley 3,000 

25,500 

Goshute Valley Steptoe Valley 4,000 Antelope Valley 500 

Great Salt Lake Desert 2,000 

4,000 2,500 

Hot Creek Valley Railroad Valley 800 

(northern part) 800 

Independence Valley Clover Valley 3,000 3,000 

Jakes Valley Long Valley 14,000 White River Valley 51,200 

Railroad Valley 

(northern part) 700 

14,000 51,900 

Little Smoky Valley Newark Valley 1,500 

Railroad Valley 

(northern part) 5,500 

7,000 

Long Valley Newark Valley 10,000 

Jakes Valley 14,000 

Railroad Valley 

(northern part) 13,000 

37,000 

Newark Valley Long Valley 10,000 

Little Smoky Valley 1,500 

11,500 

Railroad Valley Long Valley 13,000 

(northern part) Little Smoky Valley 5,500 

Hot Creek Valley 800 

Railroad Valley 

(southern part) 4,000 

Jakes Valley 700 

24,000 

Ruby Valley Huntington Valley 19,000 

Butte Valley 2,000 

21,000 

"Spring Valley Hamlin Valley 10,000 

Snake Valley 4,000 

14,000 

Steptoe Valley Goshute Valley 4,000 

Tippett Valley Great Salt Lake Desert 6,000 

Snake Valley 3,600 

9,600 

C28 Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
Table C15. Summary of estimated ground-water budgets for valleys in eastern Nevada study area 

Recharge (acre-feet per year) Discharge (acre-feet per year) 

Valley From lnterbasin 

precipitation flow in 

Antelope Valley 17,000 500 

Butte Valley 69,000 0 

Clover Valley 59,000 25,500 

Goshute Valley 41,000 4,000 

Hot Creek Valley 5,800 0 

Independence Valley 50,000 0 

Jakes Valley 38,500 14,000 

Little Fish Lake Valley 9,700 0 

Little Smoky Valley 13,000 0 

Long Valley 48,000 0 

Newark Valley 49,000 11,500 

Railroad Valley 

(northern part) 61,000 24,000 

Ruby Valley 146,000 21,000 

Spring Valley 104,000 0 

Steptoe Valley 132,000 0 

Tippett Valley 12,500 0 

An estimated 5,500 acre-ft/yr of interbasin flow 

from Little Smoky Valley in the Lockes area of Railroad Valley includes about 2,500 acre-ft/yr of discharge from springs near Lockes. In Chapter B of this 

report, about 9,000 acre-ft/yr of ground-water evapotranspiration is estimated for the Lockes area, much of 

which may be derived from interbasin flow from Little 

Smoky Valley. The occurrence of interbasin flow from 

Little Smoky Valley to Railroad Valley is consistent 

with previous studies (Rush and Everett, 1966; Van 

Denburgh and Rush, 1974). The amount of interbasin 

flow estimated from southern Little Smoky Valley was 

selected to balance the ground-water budget for Little 

Smoky Valley. 

The interbasin flow discussed above accounts for 

23,300 acre-ft/yr, which is 700 acre-ft/yr less than 

needed to balance the estimated ground-water evapotranspiration of 85,000 acre-ft/yr. The difference may 

arise because the estimated ground-water evapotranspiration is too large, or because the estimated recharge 

from precipitation is too small, or because the interbasin flow from Long Valley by way of Newark Valley is 

too small, or because interbasin flow may enter Railroad Valley from Jakes Valley to the northeast as suggested by Harrill and others (1988), or through a 

combination of these factors. Interbasin flow of 700 

Total Evapotranspiration lnterbasin 

flow out Total 

17,500 4,000 13,500 17,500 

69,000 44,500 24,500 69,000 

84,500 84,500 0 84,500 

45,000 42,500 2,500 45,000 

5,800 5,000 800 5,800 

50,000 47,000 3,000 50,000 

52,500 600 51,900 52,500 

9,700 9,700 0 9,700 

13,000 6,000 7,000 13,000 

48,000 11,000 37,000 48,000 

60,500 60,500 0 60,500 

85,000 85,000 0 85,000 

167,000 167,000 0 167,000 

104,000 90,000 14,000 104,000 

132,000 128,000 4,000 132,000 

12,500 2,900 9,600 12,500 

acre-ft/yr from Jakes Valley is assumed by the present 

study (table Cl4, pl. 4) until a more detailed investigation of interbasin flow to Railroad Valley is made. 

Total interbasin flow to northern Railroad Valley 

was estimated to be about 24,000 acre-ft/yr (table C14) 

compared to 7,000 acre-ft/yr estimated by Van Denburgh and Rush (1974). Total estimated ground-water 

recharge from precipitation and interbasin flow to 

northern Railroad Valley was estimated to be about 

85,000 acre-ft/yr (tables C13 and Cl5). 

Independence Valley System 

The Independence Valley flow system includes 

Independence, Clover, and Butte Valleys. The inclusion of Butte Valley in the Independence Valley flow 

system differs from the geographic area proposed by 

Harrill and others (1988); they included the northern 

Butte Valley hydrographic area, which includes only 

the northern one-third of Butte Valley, in the Ruby Valley flow system and the southern Butte Valley hydrographic area, which includes the southern two-thirds of 

Butte Valley, in the Goshute Valley system. Given the 

interpretation of ground-water flow for this system by 

the present study, the system might more properly be 

named the Clover Valley flow system, but the name 

given to the system by Harrill and others (1988) is 

retained for consistency. 

ESTIMATED GROUND-WATER BUDGETS AND REGIONAL FLOW C29 
Eakin and Maxey ( 1951 b) estimated recharge to 

Independence Valley to be 9,300 acre-ft/yr and discharge to be 9,500 acre-ft/yr. For Clover Valley, they 

estimated recharge of 20,700 acre-ft/yr and discharge 

of 19,000 acre-ft/yr. Glancy (1968) estimated groundwater recharge to Butte Valley of 19,000 acre-ft/yr, discharge of 19,900 acre-ft/yr, and estimated 800 acreft/yr of interbasin flow from Butte Valley to Ruby Valley. Interbasin flow from Butte Valley to Clover Valley 

was not suggested by the early investigations, although 

Harrill and others (1988) suggested minor interbasin 

flow from Clover Valley to Independence Valley and 

1,000 acre-ft/yr of interbasin flow from Butte Valley to 

Ruby Valley. Prudic and others (1995, p. D75) suggested interbasin flow to Clover Valley of 9,000 acreft/yr from the upper Humboldt River region north and 

northwest of Clover Valley. 

Recharge from precipitation to Clover Valley was 

estimated by the present study to be about 59,000 acreft/yr (tables C13 and C15) and ground-water evapotranspiration from Clover Valley was estimated to be 

about 84,500 acre-ft/yr (tables C7 and C15), leaving an 

imbalance of about 25,500 acre-ft/yr. Recharge from 

precipitation to Independence Valley was estimated 

to be about 50,000 acre-ft/yr (tables C13 and C15). 

Estimated ground-water evapotranspiration was estimated to be 47,000 acre-ft/yr (tables C7 and C15). The 

remaining 3,000 acre-ft/yr was assumed to move as 

interbasin flow to Clover Valley to the west (table C14, 

pl. 4). Ground-water level data are not available to 

determine the direction of ground-water flow, if any, 

between Independence and Clover Valleys. Annual 

recharge from precipitation to Butte Valley, south of 

Clover Valley, was estimated to be about 69,000 acreft/yr (tables C13 and C15); ground-water evapotranspiration from Butte Valley was estimated to be 44,500 

acre-ft/yr (tables C7 and C15). Of the remaining 24,500 

acre-ft/yr, 22,500 acre-ft/yr are assumed to move as 

interbasin flow northward into Clover Valley and 2,000 

acre-ft/yr are assumed to move as interbasin flow to 

Ruby Valley (table C14, pl. 4). 

The topographic divide between Clover and Butte 

Valleys is low in altitude and underlain by alluvium to 

unknown depths. Geophysical evidence (Ponce, 1992; 

Ponce and others, 1996) suggests a continuous series of 

deep bedrock basins beneath the valley floor extending 

from about the middle of the Cherry Creek Range, on 

the east side of Butte Valley, northward into central 

Clover Valley. Although the valleys are distinct topographically, Clover Valley and the northern two thirds 

of Butte Valley may constitute a single hydrologic 

basin. The southern third of Butte Valley appears to 

consist of two small deep bedrock basins (Ponce, 

1992), one west of the southern Cherry Creek Range 

and the other south of the range. The southern one-third 

of Butte Valley may be an iso"!ated, hydrologically 

closed basin or may be hydrologically associated with 

Steptoe Valley as suggested by Harrill and others 

(1988). For the analysis herein, all of Butte Valley is 

assumed to be part of the Independence Valley flow 

system. 

Ground-water levels in northern Butte Valley, 

southern Clover Valley, and eastern Ruby Valley suggest the possibility of interbasin flow from Butte Valley to adjacent areas of Clover and Ruby Valleys 

(Thomas and others, 1986). The steepest hydraulic gradient, however, is between Butte Valley and Clover 

Valley suggesting greater interbasin flow between 

these two valleys. The hydraulic gradient from the 

Christiansen well (Township 30 North, Range 62 East, 

section 33) just north of West Buttes in northern Butte 

Valley to the Spruce well (Township 31 North, Range 

62 East, section 3) in southern Clover Valley is about 

290ft in about 12 mi (Thomas and others, 1986). The 

width of alluvial fill near the topographic divide 

between the valleys is about 27,000 ft at land surface. 

However, bedrock of the bounding mountain ranges 

may not limit flow northward because limestones of the 

Permian Pequop Formation outcrop on the west side of 

the Clover Valley-Butte Valley divide area (Coats, 

1987), while carbonate rocks of the Ordovician 

Pogonip Group and of the Pennsylvanian-Permian 

(undivided) Riepe Spring Limestone and Rib Hill F~rmation (Coats, 1987) underlie Spruce mountain on the 

east side of the divide area. These formations are 

included in, or are equivalent to, the lower and upper 

carbonate aquifers of Winograd and Thordarson (1975) 

in southern Nevada (fig. C2). Assuming a section width 

of 22,000 ft and the hydraulic gradient given above, a 

transmissivity of about 27,000 ft2

/d would be required 

to allow ground-water flow of 22,500 acre-ft/yr from 

Butte Valley to Clover Valley. This transmissivity is 

within the range of transmissivity reported for the 

lower and upper carbonate aquifers in southern Nevada 

(Winograd and Thordarson, 1975, p. C30, C34). The 

average hydraulic conductivity would have to be from 

about 30 to 60 ft/d, well within the range of hydraulic 

conductivity for carbonate-rock aquifers and alluvial 

valley-fill materials reported by Plume (1996). 

C30 Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 

/ 
Glancy (1968) reported a gradient of 40ft over 

5.5 mi between northern Butte Valley and Ruby Valley 

to the west. Thomas and others (1986), using waterlevel altitudes based on more current field mapping 

indicate a gradient of 25 ft over 5.4 mi. Using this gradient, a flow section width of 10,560 ft, as estimated by 

Glancy (1968) and a transmissivity of 27,000 ft2

/d suggests interbasin flow of as much as 2,000 acre-ft/yr 

from Butte Valley to Ruby Valley. 

About 9,000 acres of northwestern Clover Valley 

along the eastern base of the East Humboldt Range are 

covered by native meadows and pasture. The meadows 

appear to be supported by shallow ground water 

derived from locally large surface-water discharge 

from watersheds in the East Humboldt Range, which 

are underlain by granitic and metamorphic rocks of 

uncertain age. This surface discharge does not have an 

opportunity to infiltrate into the subsurface until it 

leaves the bedrock areas of the watersheds in the mountain block. Ground-water evapotranspiration from 

these areas, areas which were not included in the reconnaissance estimates of ground-water evapotranspiration (Eakin and Maxey, 1951 b), was estimated to be 

about 23,000 acre-ft/yr. 

Ruby Valley System 

The Ruby Valley system includes only Ruby Valley in the present study and differs from the geographic 

area delineated by Harrill and others (1988) by excluding the northern part of Butte Valley, although a small 

amount of ground water flows from Butte Valley into 

Ruby Valley. Ground-water recharge from precipitation to Ruby Valley was estimated to be about 146,000 

acre-ft/yr (tables C13 and C15). Eakin and Maxey 

(1951a) estimated 68,000 acre-ft/yr of ground-water 

recharge to Ruby Valley. 

Ground-water evapotranspiration was estimated 

to be 167,000 acre-ft/yr (tables C7 and C15). Some of 

Ruby Lake and most, if not all, of Franklin Lake, when 

it is present, is derived from surface-water runoff. Ruby 

Lake may cover from as little as 1,000 acres to more 

than 3,500 acres. Franklin Lake is dry in many years, 

but may cover 30,000 to 45,000 acres in wet years. The 

two Lakes covered more than 49,000 acres in 1985, but 

by 1989 had been reduced to just over 1,000 acres, all 

of it in Ruby Lake. Eakin and Maxey (1951a) estimated 

ground-water discharge of 67,600 acre-ft/yr. 

About 23,500 acres of the west side of northern 

Ruby Valley along the eastern base of the Ruby Mountains are covered by native meadows and pastures, 

similar to those found in Clover Valley. Hydrologic 

conditions in northern Ruby Valley are similar to those 

in Clover Valley; locally large surface discharge occurs 

from the watersheds of the northern Ruby Mountains, 

which are underlain by Tertiary and Cretaceous granitic rocks and lower Paleozoic metamorphic rocks. 

Ground-water evapotranspiration from these areas was 

estimated to be about 4 7,500 acre-ft/yr. These areas 

were not included in areas of ground-water evapotranspiration by the reconnaissance study of Eakin and 

Maxey (1951a). 

The earlier discussion of the marsh area of southem Ruby Valley concluded that about 22,000 acre-ft/yr 

of ground water is evapotranspired from the 14,600 

acres of marshland. This is in addition to the estimated 

ground-water evapotranspiration of 145,000 acre-ft/yr 

from non-marsh vegetation in Ruby Valley, for a total 

estimated ground-water evapotranspiration of 167,000 

acre-ft/yr (table C17). This exceeds the estimated 

recharge of 146,000 acre-ft/yr from precipitation by 

21,000 acre-ft/yr. Ground-water levels in southern 

Ruby Valley are higher than those in the Franklin Lake 

area just north of Ruby Lake. Northern Ruby Valley is 

an unlikely source of any ground water with which to 

support the marshes of southern Ruby Valley. The 

most likely source is interbasin flow of recharge from 

precipitation on the west side of the southern Ruby 

Mountains that moves through the thick carbonate-rock 

sequence between Harrison Pass and Overland Pass 

(pl. 1). 

Eakin and Maxey (1951a) did not suggest interbasin ground-water flow into southern Ruby Valley, but 

did indicate that discharge from springs along the 

southwestern part of the valley may be substantially 

greater than the amount used in their estimates (Eakin 

and Maxey, 1951a, p. 83); the discharge estimate they 

used is not clear. Dudley ( 1967) estimated between 

9,000 and 15,000 acre-ft/yr of interbasin flow from the 

west slope of the southern Ruby Mountains to Ruby 

Valley along the western margin of the marshes of 

Ruby Lake based on an analysis of the hydrogeology of 

the Ruby Mountains and electric-analog modeling of 

ground-water flow. Harrill and others ( 1988) suggested 

interbasin flow of 10,000 acre-ft/yr from Huntington 

Valley, to the west, into southern Ruby Valley. Prudic 

and others (1995, p. D75) estimated interbasin flow of 

16,000 acre-ft/yr from Huntington Valley. 

The southern Ruby Mountains between Harrison 

Pass and Overland Pass (pl. 1), which border southern 

Ruby Valley to the west of Ruby Lake, is an asymmetrical fault-block mountain with a steep east-facing 

ESTIMATED GROUND-WATER BUDGETS AND REGIONAL FLOW C31 
slope and gentler western slopes. This part of the Ruby 

Mountains is underlain by a thick sequence of eastward-dipping, mostly carbonate-rock formations (fig. 

C2) ranging in age from Cambrian to Pennsylvanian 

(Dudley, 1967; Coats, 1987). At the base of the westem slope of the southern Ruby Mountains is a 4,000-ft 

sequence of middle Cambrian limestones to which 

Dudley (1967) assigned a medium to locally high permeability. Above these limestones are limestones of 

the 3,000-ft thick Pogonip Group, described by Dudley ( 1967) as the most important aquifer in the range 

because of its secondary porosity and permeability and 

because of its structural position low on the western 

slopes. Above the Pogonip is a 3,000-ft thick sequence 

of Silurian and Devonian dolomites of moderate permeability (Dudley, 1967). Finally, above these dolomites are 1, 700 ft of Devonian limestones of the 

Nevada Formation and Devils Gate limestone, most of 

which are highly permeable (Dudley, 1967). These 

formations are the lower carbonate aquifer of Winograd and Thordarson (1975) in southern Nevada (fig. 

C2). Capping the range in some localities are limestones of Pennsylvanian and Permian age that are 

hydrologically unimportant because of their topographic position (Dudley, 1967). 

The contour line representing 20 inches of precipitation on the PRISM precipitation map occurs just 

above the base of the middle Cambrian limestones on 

the western slopes of the southern Ruby Mountains. 

Applying the recharge percentages to precipitation of 

20 inches and greater falling on the western slopes of 

the mountains yields recharge of about 22,500 acreft/yr. This recharge, if most or all of it moves down-dip 

through the thick, eastward-dipping limestones and 

dolomites of the southern Ruby Mountains, is sufficient to provide the additional recharge needed to balance the ground-water budget for Ruby Valley. The 

present study suggests that as much as 19,000 acre-ft/yr 

of recharge to Ruby Valley may be through interbasin 

flow from the west slope of the southern Ruby Mountains and 2,000 acre-ft/yr from northern Butte Valley 

(pl. 4, table C14). 

Colorado System 

The Colorado flow system of Eakin (1966) and 

later Harrill and others (1988) extends far south of the 

study area. Valleys in the study area included in this 

system are the northernmost valleys of the Colorado 

system-Long and Jakes Valleys. 

Recharge from precipitation to Long Valley was 

estimated to be about 48,000 acre-ft/yr (tables C13 and 

C15) and ground-water evapotranspiration was estimated to be about 11,000 acre-ft/yr (tables C7 and 

C15). About .13,000 acre-ft/yr is believed to move as 

deep interbasin flow, perhaps through Newark Valley, 

to the springs at Duckwater in Railroad Valley (pl. 4, 

table C14). An estimated 10,000 acre-ft/yr of additional interbasin flow from Long Valley sustains 

phreatophyte evapotranspiration in northeastern and 

east-central Newark Valley, described above (pl. 4, 

table C14). The remaining 14,000 acre-ft/yr of 

recharge is believed to move as deep interbasin flow 

into and through Jakes Valley to the south (pl. 4, table 

C14). Significant deep interbasin flow out of Long 

Valley has been proposed by a number of studies, 

including those by Eakin (1961, 1966), Rush and others 

(1971), Harrill and others (1988), and Prudic and others 

(1995). Early studies estimated recharge to Long Valley of 10,300 acre-ft/yr, evapotranspiration of 2,200 

acre-ft/yr, and interbasin flow out of the valley of 8,100 

acre-ft/yr (Eakin, 1961, 1966). 

Annual recharge from precipitation to Jakes Valley was estimated by the present study to be about 

38,500 acre-ft/yr (tables C13 and C15); ground-water 

evapotranspiration, along Illipah Creek west of the 

main basin of Jakes Valley, was estimated to be about 

600 acre-ft/yr (tables C7 and C15). The balance of 

37,900 acre-ft/yr together with the 14,000 acre-ft/yr of 

interbasin flow from Long Valley leaves Jakes Valley 

as interbasin flow to upper White River Valley to the 

south (table C14), although 700 acre-ft/yr may move as 

interbasin flow to Railroad Valley. The total interbasin 

flow into White River Valley from Long and Jakes Valleys is estimated to be about 51,000 acre-ft/yr. Eakin 

(1966) estimated recharge to Jakes Valley at 17,000 

acre-ft/yr and did not quantify ground-water evapotranspiration. 

The estimated ground-water recharge and discharge for Jakes Valley are problematic. Jakes Valley 

is one of the high valleys of eastern Nevada, with the 

valley floor at or above an altitude of 6,300 ft. Consequently, estimated annual precipitation on the valley 

floor is equal to or greater than 12 inches. An estimated 

26,000 acre-ft/yr of recharge would be derived from 

precipitation on the valley floor. With ground-water 

levels estimated to be as much as 400 ft below the playa 

of Jakes Valley (Eakin, 1966), whether or not all this 

estimated recharge reaches the ground-water system is 

questionable. Gravity data suggest an alignment of 

deep bedrock basins southward from Long Valley, 

C32 Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
through Jakes Valley, into and down White River Valley (Ponce, 1992; Snyder and others, 1984). Extensive 

areas of spring discharge exist in the upper White 

River Valley, but to develop a new ground-water budget, the White River Valley would have to be studied 

to determine if the magnitude of interbasin flow from 

Long and Jakes Valleys suggested above can be substantiated. 

Goshute Valley System 

The Goshute Valley flow system includes Goshute Valley, Steptoe Valley, and perhaps the southern 

one-third of Butte Valley in the present study. Harrill 

and others (1988) included the southern two-thirds of 

Butte Valley in the Goshute Valley system. Groundwater recharge from precipitation to Goshute Valley 

was estimated to be about 41,000 acre-ft/yr and 

ground-water evapotranspiration was estimated to be 

42,500 acre-ft/yr (tables C7, C13, and C15). This compares to recharge of 10,400 acre-ft/yr and evapotranspiration of 10,075 acre-ft/yr estimated by Eakin and 

others (1951a) for Goshute-Antelope Valley, an area 

larger than the Goshute Valley as defined for the 

present study. Ground-water recharge from precipitation to Steptoe Valley was estimated to be about 

132,000 acre-ft/yr. Ground-water evapotranspiration 

from the valley was estimated to be about 128,000 

acre-ft/yr (tables C7, C11, and C15). This compares to 

an estimated recharge of 85,000 acre-ft/yr and discharge of71,000 acre-ft/yr estimated by Eakin and others (1967). 

Harrill and others (1988) have suggested about 

2,000 acre-ft/yr of interbasin flow from Goshute Valley 

to the Great Salt Lake Desert to the east and minor 

interbasin flow into Antelope Valley to the southeast. 

Eakin and others (1967) suggested about 1,000 acreft/yr of interbasin flow from Steptoe Valley north of 

Currie into Goshute Valley in the Nelson Creek area 

(pl. 1). Allowing 4,000 acre-ft/yr of interbasin flow 

from Steptoe Valley, north of Currie, into Goshute Valley, balances the ground-water budget for Steptoe Valley (pl. 4) and provides sufficient additional recharge to 

Goshute Valley to balance the budget there also (pl. 4; 

tables C14 and C15). 

Great Salt Lake Desert System 

Antelope, Tippett, and Spring Valleys in eastern 

Nevada are part of the Great Salt Lake Desert flow system of Harrill and others (1988), which includes all or 

parts of 13 more valleys in western Utah. Recharge 

from precipitation to Antelope Valley was estimated by 

the present study to be about 17,000 acre-ft/yr and 

ground-water evapotranspiration was estimated to be 

about 4,000 acre-ft/yr (tables C7, C13, and C15). 

Recharge to Tippett Valley was estimated to be about 

12,500 acre-ft/yr and ground-water evapotranspiration 

was estimated to be about 2,900 acre-ft/yr (tables C7, 

C13, and C15). The large difference between estimated 

recharge and estimated ground-water evapotranspiration for Antelope and Tippett Valleys may, in part, 

result from errors in both estimates, but the difference 

is so great that recharge to these two valleys probably 

exceeds estimated ground-water evapotranspiration by 

a considerable amount. Significant interbasin groundwater flow from these valleys has been suggested by an 

earlier study. Harrill ( 1971) proposed interbasin flow of 

300 acre-ft/yr from Goshute Valley to Antelope Valley 

and 4,900 acre-ft/yr from Antelope Valley to the Great 

Salt Lake Desert to the east. He also proposed 5,000 

,acre-ft/yr of interbasin flow from Tippett Valley to the 

Great Salt Lake Desert and 2,000 acre-ft/yr from Tippett Valley to Spring Valley. Harrill and others (1988) 

suggested minor interbasin flow into Antelope Valley 

from Goshute Valley; 8,000 acre-ft/yr of interbasin 

flow from Antelope Valley to the Great Salt Lake 

Desert; 2,000 acre-ft/yr of interbasin flow from Tippett 

Valley to the Great Salt Lake Desert; 3,000 acre-ft/yr 

from Tippett Valley to Antelope Valley; and 2,000 acreft/yr from Tippett Valley to Spring Valley. 

The present study suggests that all recharge to 

Antelope and Tippett Valleys in excess of ground-water 

evapotranspiration discharges ultimately to the Great 

Salt Lake Desert. About 13,500 acre-ft/yr of recharge 

to Antelope Valley are estimated to leave Antelope Valley as interbasin flow to the Great Salt Lake Desert to 

the east (pl. 4, table C14) and about 9,600 acre-ft/yr are 

estimated to leave Tippett Valley as interbasin flow (pl. 

4, tables C14 and C15), with about 6,000 acre-ft/yr 

flowing through southern Antelope Valley and ultimately to the Great Salt Lake Desert. The remaining 

3,600 acre-ft/yr of interbasin flow from Tippett Valley 

is to the Great Salt Lake Desert in the area of Salt Lake 

Marsh. Much of the recharge to Antelope Valley occurs 

in the Goshute Mountains north of Alternate U.S. 

Highway 93 (pl. 1). The mountains in this area are 

underlain mainly by Devonian carbonate rocks, part 

of the lower carbonate aquifer of Winograd and 

Thordarson (1975). Much of the recharge to Tippett 

Valley occurs in the Antelope Range, which bounds 

Tippett Valley on the west. These mountains, in 

Tippett Valley, are underlain by lowef Paleozoic 

ESTIMATED GROUND-WATER BUDGETS AND REGIONAL FLOW C33 
carbonates, including the Pogonip limestone and Devonian carbonate rocks of the lower carbonate aquifer of 

Winograd and Thordarson (1975), and carbonate rocks 

of the Permian Arcturus Formation, part of the upper 

carbonate aquifer of Winograd and Thordarson (1975). 

A smaller area of recharge occurs in southeastern Tippet Valley in the Kern Mountains, which are comprised 

largely of Tertiary volcanic rocks, but are flanked north 

and south by carbonate rocks of Devonian and Permian 

age. 

Water-level data are sparse in these two valleys 

(Harrill, -1971; Thomas and others, 1986). The data for 

Tippett Valley are ambiguous, but suggest much of the 

available_ recharge from the Antelope Range may flow 

northward through southern Antelope Valley or northeastward into Deep Creek Valley (pl. 1). About 6,000 

acre-ft/yr of ground water from Tippett Valley are 

believed_io join 13,000 acre-ft/yr of ground water from 

Antelope Valley and discharge at Big Salt Spring and 

Little Salt Spring near Blue Lakes (pls. 1 and 4) east of 

the Gosh.ute Mountains that border Antelope Valley on 

the northeast. Gates and Kruer (1981, p. 18) suggested 

that all the measured 19,000 acre-ft/yr of discharge at 

these sp~ings was derived from recharge to topographic 

basins iri:Nevada. Recharge to the Kern Mountains in 

southeastern Tippett Valley probably moves down 

Pleasant. Valley, north of the Kern Mountains, and 

through the carbonate rocks and alluvium south of the 

mountaii;ls to Snake Valley (pls. 1 and 4). Altogether, 

about 3,600 acre-ft/yr of recharge originating in southeastern '"fippett Valley may move as interbasin flow to 

Snake Valley. 

Recharge from precipitation to Spring Valley was 

estimated to be about 104,000 acre-ft/yr. Ground-water 

evapotranspiration from Spring Valley was an estimated 90,000 acre-ft/yr (tables C7, C13, and C15). The 

difference of 14,000 acre-ft/yr may be the result of an 

underestimation of discharge by evapotranspiration of 

ground-\yater, an overestimation of recharge, or a combination·of errors in both estimates. However, much of 

the excess recharge is believed to leave the valley as 

interbasi!l flow to the east (pl. 4, tables C14 and C15). 

Rush and Kazmi ( 1965) estimated about 4,000 acreft/yr of subsurface outflow of ground water from 

Spring Valley to Hamlin Valley through the carbonate 

rocks ofihe southern Snake Range. Field observation 

indicates: the southern end of the phreatophyte area in 

southern·· Spring Valley is about coincident with the 

intersection of southeastward-dipping massive Upper 

Cambrian limestones and the valley floor. These limestones are one of the major water-bearing units of the 

lower carbonate aquifer (fig. C2) of Winograd and 

Thordarson (1975). Rush and Kazmi (1965), while 

suggesting that the subsurface flow is principally 

through the carbonate rocks of the southern Snake 

Range, use an estimated transmissivity for the alluvium 

of about 6,700 ft2/d in calculating the flow. This 

implied a hydraulic conductivity as small as about 2 

ft/d, considerably lower than the mean and median values of 80 and 6 ft/d for the hydraulic conductivity of the 

lower carbonate aquifer reported by Winograd and 

Thordarson (1975). The estimated interbasin flow of 

Rush and Kazmi ( 1965), therefore, can be increased 

easily by a factor of two or three to an estimated 8,000 

to 12,000 acre-ft/yr. 

Another area where interbasin flow from Spring 

Valley may occur is in the area between the Kern 

Mountains and the northern end of the Snake Range 

(pl. 1). This low-altitude area is underlain by an eastwest trending series of gravity lows (Ponce, 1992) and 

by sedimentary deposits surrounding outcrops of Tertiary volcanic rocks and carbonate rocks of the Permian 

Arcturus Formation; the Pogonip limestone outcrops 

on the east side of the Red Hills just north of these alluvial deposits (Hose and Blake, 1976). Water-level data 

for the area of Spring Valley just to the west of this 

low-altitude area are sparse and ambiguous (Rush and 

Kazmi, 1965; Thomas and others, 1986). Interbasin 

flow may be significant from Spring Valley through the 

sedimentary and carbonate-rock deposits of this area to 

a large area of phreatophytes around Salt Marsh Lake 

near Gandy, Utah. Additional hydrologic and hydrogeologic studies in Snake and Hamlin Valleys and the 

Great Salt Lake Desert are needed to corroborate the 

estimates of interbasin flow from Antelope, Tippett, 

and Spring Valleys. 

SUMMARY AND CONCLUSIONS 

Ground-water budgets were estimated for 16 contiguous valleys covering nearly 15,000 mi2 of the central Great Basin in Elko, White Pine, Nye, Eureka, and 

Lincoln Counties of eastern Nevada. The geologically 

complex terrain of the study area consists of valleys 

underlain by unconsolidated deposits of Quaternary 

age bounded by mountain ranges of folded and faulted 

rocks ranging in age from Precambrian to late Tertiary. 

The valleys and bounding mountain ranges generally 

trend north-south with the exception of the Ruby 

Mountains and the East Humboldt, Quinn Canyon, and 

C34 Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
Grant Ranges, which trend northeast-southwest. The 

climate of the area ranges from an arid middle-latitude 

desert on the valley floors to a subhumid continental 

climate in the highest mountain ranges. Vegetation 

varies from desert scrub at the lowest altitudes to subalpine forest and alpine tundra at the highest altitudes. 

Early ground-water resources studies in the 

Nevada part of the Great Basin recognized that most 

ground water is discharged from the topographically 

closed valleys by evapotranspiration. Reconnaissancelevel studies from the late 1940's to the mid-1970's 

estimated ground-water budgets for the valleys of the 

study area. Ground-water evapotranspiration estimated 

by these studies was based on the results of field studies 

made before 1930. Ground-water recharge estimated 

by these studies was based on precipitation data first 

published in 1936. However, the reconnaissance level 

ground-water budgets should be reconsidered because 

of the results of ground-water evapotranspiration field 

studies since 1980, the availability of more recent precipitation data, and more advanced technologies. 

The results of the present study are based on these 

more recent data, methods, and technologies. Groundwater discharge by evapotranspiration was estimated 

from field studies of phreatophyte evapotranspiration, 

the results of which were correlated to plant cover. 

Estimates of phreatophyte plant cover were determined 

at regional scales from a vegetation index derived from 

Landsat data. Ground-water evapotranspiration estimated by the present study totaled about 790,000 acreft/yr, and exceeded previous estimates by a little more 

than two times. A new precipitation map for Nevada, 

based on the PRISM methodology, was used to estimate the volume of precipitation in each valley of the 

study area. New estimates of ground-water recharge 

from precipitation were based on the new estimates 

of ground-water evapotranspiration and interbasin 

ground-water flow in 15 of the 16 valleys of the study 

area. No recharge was assumed for areas with annual 

precipitation of less than 8 inches. Recharge was estimated to be about 0.8 percent of annual precipitation 

from 8 to less than 12 inches, about 13.0 percent of precipitation from 12 to less than 16 inches, about 14.4 

percent of precipitation from 16 to less than 20 inches, 

about 15.8 percent of precipitation from 20 to less than 

34 inches, and about 62.6 percent of precipitation equal 

to or greater than 34 inches. Ground-water recharge 

estimated by the present study totaled about 855,000 

acre-ft/yr, a little more than twice the amount estimated 

by previous studies. 

The estimates of ground-water discharge by 

evapotranspiration and ground-water recharge from 

precipitation were used to develop revised groundwater budgets for all or parts of seven regional groundwater flow systems in eastern Nevada (table C16). 

These flow systems include the Newark Valley, Railroad Valley, Independence Valley, Ruby Valley, Colorado, Goshute Valley, and Great Salt Lake Desert flow 

systems. The estimated ground-water budget for each 

valley is based on the conventional assumption that 

hydrologic boundaries are coincident with topographic 

boundaries. Budgets for individual valleys were 

balanced by assuming interbasin ground-water flow 

from or to adjacent valleys within the boundaries of the 

Table C16. Summary of estimated ground-water budgets for regional flow systems in eastern Nevada study area 

and tor overall study area 

Recharge (acre-feet per year) Discharge (acre-feet per year) 

Regional flow system From lnterbasin Total Evapotranspiration lnterbasin 

precipitation flow in flow out Total 

Newark Valley system 56,500 10,000 66,500 66,500 0 66,500 

Railroad Valley system 82,000 17,700 99,700 99,700 0 99,700 

Independence Valley system 178,000 0 178,000 176,000 2,000 178,000 

Ruby Valley system 146,000 21,000 167,000 167,000 0 167,000 

Colorado system 86,500 0 86,500 11,600 74,900 86,500 

Goshute Valley system 173,000 0 173,000 170,500 2,500 173,000 

Great Salt Lake Desert system 133,500 500 134,000 96,900 37,100 134,000 

Overall study area 1 855,000 2

23,000 2878,000 788,000 2

90,000 2878,000 

1 Numbers are rounded to the nearest 1,000 acre-feet per year. 2 Total includes only interbasin ground-water flow entering or leaving overall study area (interbasin flow between flow systems within study 

area is not included). 

SUMMARY AND CONCLUSIONS C35 
flow system. Much of the assumed interbasin flow may 

more properly reflect recharge in areas where hydrologic divides diverge from topographic divides. 

Recharge from precipitation to the Newark Valley ground-water flow system, which is comprised of 

Newark Valley and northern and central Little Smoky 

Valley, was estimated to be about 56,500 acre-ft/yr. An 

estimated 10,000 acre-ft/yr of ground water is assumed 

to enter the Newark Valley system as interbasin flow 

from Long Valley. Ground-water evapotranspiration 

from the system was estimated to total about 66,500 

acre-ft/yr. 

The Railroad Valley system includes Little Fish 

Lake Valley, the southern part of Little Smoky Valley, 

Hot Creek Valley, and the northern part of Railroad 

Valley. Total recharge from precipitation to this system 

was estimated to be about 82,000 acre-ft/yr. Regional 

interbasin ground-water flow into the Railroad Valley 

system from Long Valley, probably through Newark 

Valley, was estimated to be about 13,000 acre-ft/yr. 

Another 700 acre-ft/yr may enter Railroad Valley from 

Jakes Valley and about 4,000 acre-ft/yr may enter the 

northern part of Railroad Valley from the southern part. 

Total recharge to the Railroad Valley system was estimated to be about 99,700 acre-ft/yr. Estimated groundwater evapotranspiration from the valleys of the Railroad Valley system also totaled about 99,700 acre-ft/yr. 

Recharge from precipitation to the Independence 

Valley system, which includes Independence, Clover, 

and Butte Valleys, was estimated to be about 178,000 

acre-ft/yr and ground-water evapotranspiration was 

estimated to be about 176,000 acre-ft/yr; 2,000 acreft/yr may move as interbasin flow from northern Butte 

Valley to Ruby Valley. 

The Ruby Valley flow system includes only Ruby 

Valley. Total recharge from precipitation was estimated to be 146,000 acre-ft/yr; as much as 19,000 acreft/yr are assumed to enter Ruby Valley as interbasin 

flow from precipitation on the west slopes of the southem Ruby Mountains. Another 2,000 acre-ft/yr are 

assumed to recharge Ruby Valley as interbasin flow 

from northern Butte Valley. Total ground-water evapotranspiration was estimated to be about 167,000 acreft/yr. 

Long and Jakes Valleys are the northern-most 

valleys of the Colorado system, which stretches far 

south of the study area. Recharge from precipitation to 

Long and Jakes Valleys was estimated to be about 

86,500 acre-ft/yr while estimated ground-water 

evapotranspiration was about 11,600 acre-ft/yr. 

About 10,000 acre-ft/yr was estimated to move as 

interbasin flow from Long Valley to Newark Valley. 

Another 13,000 acre-ft/yr was estimated to leave Long 

Valley, possibly flowing through southern Newark 

Valley, as regional interbasin flow to springs in Railroad Valley near Duckwater. The remaining 14,000 

acre-ft/yr of recharge to Long Valley is assumed to 

move as interbasin flow, together with as much as 

37,200 acre-ft/yr of recharge to Jakes Valley, to the 

White River Valley. About 700 acre-ft/yr of recharge 

to Jakes Valley may move as interbasin flow to Railroad Valley. 

Goshute and Steptoe Valleys comprise the 

Goshute Valley flow system. Recharge from precipitation to Goshute and Steptoe Valleys was estimated to 

be about 173,000 acre-ft/yr and ground-water evapotranspiration was estimated to be about 170,500 acreft/yr. About 2,000 acre-ft/yr were assumed to leave 

Goshute Valley as interbasin flow to the Great Salt 

Lake Desert flow system and about 500 acre-ft/yr as 

interbasin flow to Antelope Valley. 

Spring, Antelope, and Tippett Valleys are part of 

the Great Salt Lake Desert flow system, which includes 

13 more valleys in Utah. Total estimated recharge from 

precipitation to the three valleys in the study area was 

estimated at about 133,500 acre-ft/yr plus an estimated 

500 acre-ft/yr as interbasin flow from Goshute Valley 

to Antelope Valley for a total recharge of 134,000 acreft/yr. Total ground-water evapotranspiration was estimated to be about 96,900 acre-ft/yr. The balance of 

37,100 acre-ft/yr is proposed to move as interbasin 

flow into other valleys of the Great Salt Lake Desert 

system to the east. 

Regional interbasin ground-water flow between 

the valleys and flow systems of eastern Nevada has 

been estimated by earlier studies, but the present study 

proposes interbasin flow in greater magnitude and, in 

some places, between valleys other than those previously suggested. The proposed areas of interbasin flow, 

or perhaps shift in hydrologic-basin boundaries that 

may more properly reflect the fact that hydrologic 

divides are not coincident with topographic divides, are 

based on geologic, geophysical, and hydrologic data. 

Regional interbasin ground-water flow from Long Valley to Jakes Valley and Railroad Valley has been suggested by previous investigations. Interbasin flow to 

Newark Valley from Long Valley has not been suggested by earlier studies, but is supported by analysis of 

the distribution of ground-water evapotranspiration in 

Newark Valley developed during the present study. 

C36 Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
Interbasin flow from Butte Valley to Clover Valley had 

not been suggested by earlier studies, but is supported 

by the large estimated recharge to Butte Valley, available water-level data, and geologic conditions in the 

area between Butte and Clover Valleys. Interbasin flow 

of about 4,000 acre-ft/yr from Spring Valley to Snake 

Valley was estimated by a previous study, but the volume was increased to an estimated 10,000 acre-ft/yr by 

the present study. Interbasin flow of about 5,000 acreft/yr from Antelope Valley and 7,000 acre-ft/yr from 

Tippett had been proposed by an earlier study; these 

amounts were increased by the present study and are 

supported by spring discharge measurements. New 

studies of ground-water budgets using the current 

methods for estimating ground-water recharge and 

evapotranspiration in the White River Valley and the 

rest of the Colorado flow system, as well as the other 

valleys of the Great Salt Lake Desert system, would 

allow the testing and substantiation of the new estimates of interbasin ground-water flow. 

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C38 Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
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---1994, Groundwater discharge by phreatophyte 

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Ground-water levels in the Great Basin region of 

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2 sheets. 

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mineral resources of Lincoln County, Nevada: Nevada 

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Watson, P., Sinclair, P., and Waggoner, R., 1976, Quantitative evaluation of a method for estimating recharge to 

the desert basins of Nevada: Journal of Hydrology, 

v. 31' p. 335-357. 

Weeks, E.P., Weaver, H.L., Campbell, G.S, and Tanner, 

B.D., 1987, Water use by saltcedar and by replacement 

vegetation in the Pecos River floodplain between Acme 

and Artesia, New Mexico: U.S. Geological Survey Professional-Paper 491-G, 33 p. 

White, W.N., 1932, A method of estimating ground-water 

supplies based on discharge by plants and evaporation 

from soil-Results of investigations in Escalante Valley, Utah, in Contributions to the hydrology of the 

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Winograd, I.J., and Thordarson, William, 1975, Hydrogeologic and hydrochemical framework, south-central 

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to the Nevada Test Site: U.S. Geological Survey Professional Paper 712-C, 126 p. 

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vegetation: California Department of Public Works, 

Division of Water Resources, Bulletin 50, 160 p. 

C40 Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
~ m 

rm 

0 

"""' -... 

0 

~ 

~" ~ 

Table C17. Estimated ground-water discharge by evapotranspiration from valleys in eastern Nevada study area, 1985 and 1989 1 

Antelope Valley 

Butte Valley 

Clover Valley 

Goshute Valley 

Open water 

Playa I Bare soil 

Average 

cover 

<10 percent plant cover 0.046 

10 to <20 percent plant cover .126 

20 to <35 percent plant cover .259 

35 to <50 percent plant cover 

Total 

Open water 

Playa I Bare soil 

< 10 percent plant cover 

10 to <20 percent plant cover 

20 to <35 percent plant cover 

35 to <50 percent plant cover 

~0 percent plant cover 

Total 

Open water 

Playa I Bare soil 

<10 percent plant cover 

10 to <20 percent plant cover 

20 to <35 percent plant cover 

35 to <50 percent plant cover 

~50 percent plant cover 

Total 

Open water 

Playa I Bare soil 

<1 0 percent plant cover 

10 to <20 percent plant cover 

20 to <35 percent plant cover 

35 to <50 percent plant cover 

~50 percent plant cover 

Total 

.059 

.140 

.248 

.420 

.595 

.078 

.138 

.258 

.422 

.620 

.047 

.134 

.256 

.414 

.583 

Area 

(acres) 

0 

279 

10,894 

108 

11,282 

32 

1,315 

64,990 

8,043 

1,977 

468 

176 

77,001 

7,347 

2,072 

15,968 

22,551 

10,042 

4,009 

4,276 

66,265 

8 

4,197 

129,981 

1,178 

377 

95 

47 

135,883 

1985 

Evapotranspiration 

Annual 

average 

rate (feet) 

0.150 

.164 

1.200 

2.172 

.150 

.314 

1.346 

2.110 

2.507 

2.585 

.150 

.566 

1.328 

2.147 

2.509 

2.587 

.150 

.192 

1.275 

2.143 

2.502 

2.588 

Summer 

(acrefeet) 

1,239 

93 

2 

1,334 

14,282 

7,835 

3,107 

898 

355 

26,477 

6,381 

21,661 

16,095 

7,700 

8,624 

60,461 

17,384 

1,084 

603 

181 

95 

19,347 

Winter 

(acrefeet) 

544 

36 

581 

Annual 

(acrefeet) 

0 

(2) 

1,783 

129 

3 

1,915 

(3) 

197 

6,125 20,407 

2,988 10,823 

1,062 4,169 

275 1,173 

101 456 

10,551 37,225 

2,658 

8,279 

5,462 

2,359 

2,440 

21,198 

(3) 

311 

9,039 

29,940 

21,557 

10,059 

11,064 

81,970 

(3) 

630 

7,578 24,962 

417 1,501 

205 808 

56 237 

27 122 

8,283 28,260 

Average 

cover 

0.073 

.117 

.242 

.398 

.081 

.129 

.251 

.419 

.631 

.080 

.131 

.270 

.420 

.686 

.078 

.117 

.264 

.409 

.688 

Area 

(acres) 

0 

19 

9,994 

1,263 

4 

1 

11,281 

3 

213 

58,335 

15,050 

2,314 

623 

465 

77,003 

3 

4,107 

17,816 

26,891 

6,930 

4,011 

6,508 

66,266 

41 

118,816 

16,275 

491 

149 

109 

135,882 

1989 

Evapotranspiration 

Annual 

average 

rate (feet) 

0.150 

.479 

1.101 

2.082 

2.489 

.150 

.580 

1.221 

2.120 

2.507 

2.584 

.150 

.601 

1.256 

2.189 

2.507 

2.584 

.150 

.537 

1.095 

2.168 

2.496 

2.579 

Summer 

(acrefeet) 

3,367 

997 

6 

4,371 

23,847 

13,241 

3,658 

1,195 

937 

42,878 

7,572 

24,355 

11,354 

7,694 

13,166 

64,141 

44,894 

12,770 

796 

284 

220 

58,964 

Winter Annual 

(acre- (acrefeet) fc:et) 

1,422 

394 

2 

0 

1,818 

0 

(2) 

4,789 

1,391 

8 

6,189 

(3) 

32 

10,002 33,849 

5,131 18,372 

1,248 4,906 

367 1,562 

264 1,201 

17,012 59,922 

3,142 

9,408 

3,818 

2,360 

3,649 

22,377 

(3) 

616 

10,714 

33,763 

15,172 

10,054 

16,815 

87,134 

(3) 

6 

18,902 63,796 

5,049 17,819 

269 1,065 

88 372 

61 281 

24,369 83,339 
~ Table C17. Estimated ground-water discharge by evapotranspiration from valleys in eastern Nevada study area, 1985 and 1989 1

-Continued 

0 

';j 

I» 

~ ~ 

:::D 

CD 

cc 

s· 

::I 

~ 

C) 

0 

c 

::I 

Q. 

:e 

I» 

~ 

m 

c 

Q. 

cc 

~ en 

I» 

::I 

Q. 

C) 

0 

c 

::I 

Q. 

:e 

I» 

~ "T1 

0 

~ 

m 

I» 

!e. 

CD 

3 

z 

CD 

< I» 

Q. 

I» 

Hot Creek Valley 

Independence Valley 

Jakes Valley 

Little Fish Lake Valley 

Open water 

Playa I Bare soil 

< 10 percent plant cover 

10 to <20 percent plant cover 

20 to <35 percent plant cover 

35 to <50 percent plant cover 

~50 percent plant cover 

Total 

Open water 

Playa I Bare soil 

< 10 percent plant cover 

10 to <20 percent plant cover 

20 to <35 percent plant cover 

35 to <50 percent plant cover 

~50 percent plant cover 

Total 

Open water 

Playa I Bare soil 

< 10 percent plant cover 

10 to <20 percent plant cover 

20 to <35 percent plant cover 

35 to <50 percent plant cover 

~50 percent plant cover 

Total 

Open water 

Playa I Bare soil 

<10 percent plant cover 

10 to <20 percent plant cover 

20 to <35 percent plant cover 

35 to <50 percent plant cover 

~50 percent plant cover 

Totai 

Average 

cover 

0.072 

.146 

.253 

.411 

.613 

.061 

.131 

.223 

.382 

.080 

.154 

.248 

.399 

.638 

.078 

.143 

.260 

.417 

.587 

Area 

(acres) 

0 

20 

1,084 

1,819 

620 

168 

67 

3,778 

211 

15,162 

77,224 

9,494 

488 

4 

102,583 

35 

8 

16 

218 

122 

12 

5 

416 

800 

37 

1,803 

3,791 

1,178 

387 

176 

8,i72 

1985 

Evapotranspiration 

Annual 

average 

rate (feet) 

0.150 

.490 

1.415 

2.127 

2.499 

2.586 

.150 

.355 

1.250 

2.008 

2.467 

.150 

.604 

1.492 

2.112 

2.486 

2.586 

.150 

.549 

1.386 

2.156 

2.505 

2.586 

Summer 

(acrefeet) 

374 

1,868 

984 

321 

134 

3,681 

19,225 

8,565 

726 

8 

28,524 

7 

237 

193 

24 

10 

471 

698 

3,807 

1,897 

741 

353 

7,496 

Winter 

(acrefeet) 

157 

707 

335 

99 

38 

1,336 

8,167 

3,307 

253 

2 

11,729 

3 

89 

66 

7 

3 

168 

292 

1,447 

642 

228 

101 

'\""71(\ 

~,I J.V 

Annual 

(acrefeet) 

0 

3 

531 

2,575 

1,319 

420 

172 

5,020 

(3) 

2,274 

27,392 

11,872 

979 

10 

42,527 

(3) 

(2) 

10 

326 

259 

31 

13 

639 

600 

6 

990 

5,254 

2,539 

969 

454 

1(\ 01'"! J.V,UJ.._ 

Average 

cover 

0.077 

.146 

.251 

.414 

.589 

.073 

.119 

.250 

.398 

.538 

.088 

.140 

.243 

.078 

.141 

.255 

.402 

.559 

Area 

(acres) 

0 

7 

1,167 

1,857 

551 

123 

73 

3,778 

4,606 

77,604 

19,397 

892 

78 

5 

102,583 

7 

4 

81 

285 

40 

417 

187 

31 

2,890 

3,845 

1,003 

187 

27 

8,170 

1989 

Evapotranspiration 

Annual 

average 

rate (feet) 

0.150 

.542 

1.406 

2.120 

2.501 

2.587 

.150 

.507 

1.113 

2.118 

2.484 

2.580 

.150 

.693 

1.352 

2.091 

.150 

.561 

1.356 

2.138 

2.489 

2.584 

Summer Winter Annual 

(acre- (acre- (acrefeet) feet) feet) 

446 

1,894 

872 

235 

146 

3,593 

27,712 

15,488 

1,408 

148 

10 

44,766 

40 

279 

62 

381 

1,143 

3,776 

1,601 

355 

55 

6,930 

.-.-

187 

717 

297 

72 

42 

1,315 

0 

633 

2,611 

1,169 

307 

188 

4,909 

(3) 

691 

11,614 39,326 

6,102 21,590 

481 1,889 

46 194 

3 13 

18,246 63,703 

16 

107 

21 

145 

477 

1,439 

544 

110 

16 

(3) 

(2) 

56 

386 

83 

526 

600 

5 

1,620 

5,215 

2,145 

465 

71 

2,586 10,121 
~ IJI 

r 

m 

(") 

.... 

...... 

(") 

~ 

w 

J ... ~-

Table C17. Estimated ground-water discharge by evapotranspiration from valleys in eastern Nevada study area, 1985 and 1989 1-Continued 

Little Smoky Valley 

Long Valley 

Newark Valley 

Railroad Valley 

(northern part) 

Open water 

Playa I Bare soil 

Average 

cover 

<10 percent plant cover 0.048 

10 to <20 percent plant cover .145 

20 to <35 percent plant cover .268 

35 to <50 percent plant cover .410 

;?:50 percent plant cover .687 

Total 

Open water 

Playa I Bare soil 

<10 percent plant cover 

10 to <20 percent plant cover 

20 to <35 percent plant cover 

35 to <50 percent plant cover 

Total 

Open water 

Playa I Bare soil 

<10 percent plant cover 

l 0 to <20 percent plant cover 

20 to <35 percent plant cover 

35 to <50 percent plant cover 

;?:50 percent plant cover 

Total 

Open water 

Playa I Bare soil 

< 10 percent plant cover 

10 to <20 percent plant cover 

20 to <35 percent plant cover 

35 to <50 percent plant cover 

~50 percent plant cover 

Total 

.066 

.119 

.218 

.068 

.136 

.256 

.414 

.638 

.049 

.132 

.266 

.420 

.684 

Area 

(acres) 

1 

600 

3,403 

953 

865 

298 

192 

6,312 

3 

985 

19,253 

1,633 

8 

21,882 

9,860 

13,920 

32,742 

18,970 

5,476 

1,513 

784 

83,265 

16 

77,549 

143,367 

17,849 

3,663 

1,874 

2,477 

246,795 

1985 

Evapotranspiration 

Annual 

average 

rate (feet) 

0.150 

.232 

1.396 

2.185 

2.497 

2.582 

.150 

.374 

1.113 

1.983 

.150 

.443 

1.301 

2.142 

2.501 

2.584 

.150 

.232 

1.266 

2.174 

2.507 

2.582 

Summer 

(acrefeet) 

553 

965 

1,414 

569 

388 

3,889 

5,040 

1,304 

11 

6,355 

10,216 

17,832 

8,756 

2,895 

1,580 

41,279 

23,243 

16,315 

5,954 

3,596 

5,006 

54,114 

Winter 

(acrefeet) 

236 

365 

476 

175 

108 

1,360 

2,158 

514 

4 

2,676 

Annual 

(acrefeet) 

(3) 

90 

789 

1,330 

1,890 

744 

496 

5,339 

(3) 

148 

7,198 

1,818 

15 

9,179 

(3) 

2,088 

4,296 14,512 

6,842 24,674 

2,974 11,730 

891 3,786 

445 2,025 

15,448 58,815 

50 

11,632 

9,959 33,202 

6,290 22,605 

2,008 7,962 

1,103 4,699 

1,390 6,396 

20,750 86,546 

Average 

cover 

0.062 

.139 

.265 

.413 

.620 

.077 

.113 

.248 

.397 

.062 

.130 

.263 

.413 

.625 

.049 

.135 

.262 

.418 

.636 

Area 

(acres) 

0 

45 

3,227 

1,563 

950 

359 

167 

6,311 

0 

330 

19,934 

1,606 

10 

2 

21,882 

5 

9,250 

45,826 

21,427 

4,460 

1,466 

832 

83,266 

31 

47,822 

176,210 

15,339 

3,910 

1,801 

1,682 

246,795 

1989 

Evapotranspiration 

Annual 

average 

rate (feet) 

0.150 

.374 

1.334 

2.174 

2.500 

2.587 

.150 

.540 

1.045 

2.107 

2.486 

.150 

.410 

1.239 

2.165 

2.500 

2.582 

.150 

.224 

1.290 

2.163 

2.505 

2.587 

Summer 

(acrefeet) 

849 

1,508 

1,544 

686 

338 

4,925 

7,578 

1,200 

16 

3 

8,797 

13,231 

19,138 

7,218 

2,803 

1,674 

44,064 

27,535 

14,293 

6,320 

3,453 

3,396 

54,997 

Winter Annual 

(acre- (acrefeet) feet) 

359 

576 

521 

211 

95 

1,762 

3,191 

478 

6 

1 

3,676 

0 

7 

1,208 

2,084 

2,065 

897 

433 

6,694 

0 

49 

10,769 

1,678 

22 

4 

12,522 

(3) 

1,388 

5,540 18,771 

7,406 26,544 

2,440 9,658 

863 3,666 

474 2,148 

16,723 62,175 

50 

7,173 

11,883 39,418 

5,493 19,786 

2,137 8,457 

1,060 4,513 

956 4,352 

21,529 83,749 
Table C17. Estimated ground-water discharge by evapotranspiration from valleys in eastern Nevada study area, 1985 and 1989 1

-Continued 

0 

t 

0 

:::r 

t» 

'9. 

CD 

... 

Average 

cover 

Area 

(acres) 

1985 

Evapotranspiration 

Annual 

average 

rate (feet) 

Summer 

(acrefeet) 

Winter 

(acrefeet) 

Annual 

(acrefeet) 

~ Ruby Valley 

:J:J 

CD 

CQ 

(5" 

::::s 

!!!. 

C) 

... 

0 

c 

::::s 

a. 

~ CD 

... 

m 

c 

a. 

CQ 

~ tn 

t» 

::::s 

a. 

C) 

0 

c 

::::s 

a. 

:: 

... 

~ ., 

~ m 

t» 

; 

3 

z 

CD 

< t» 

a. 

t» 

Open water4 

Playa I Bare soil4 

<10 percent plant cover4 

10 to <20 percent plant cover4 

20 to <35 percent plant cover4 

35 to <50 percent plant cover4 

~50 percent plant cover4 

Ruby Lake/Marsh 

0.065 

.146 

.256 

.420 

.608 

45,609 

4,688 

28,880 

32,930 

20,611 

7,380 

5,046 

14,637 

0.150 

.406 

1.410 

2.141 

2.508 

2.586 

8,258 

33,687 

32,932 

14,163 

10,161 

3,481 

12,736 

11,188 

4,343 

2,887 

(5) 

703 

11,739 

46,423 

44,120 

18,506 

13,048 

22,000 

Total 159,781 4 99,201 4 34,635 156,539 

Spring Valley 

Steptoe Valley 

Tippett Valley 

Open water 

Playa I Bare soil 

< 10 percent plant cover 

10 to <20 percent plant cover 

20 to <35 percent plant cover 

35 to <50 percent plant cover 

~50 percent plant cover 

Total 

Open water 

Playa I Bare soil 

< 10 percent plant cover 

10 to <20 percent plant cover 

20 to <35 percent plant cover 

35 to <50 percent plant cover 

~50 percent plant cover 

Total 

Open water 

Playa I Bare soil 

<10 percent plant cover 

10 to <20 percent plant cover 

20 to <35 percent plant cover 

35 to <50 percent plant cover 

Total 

.054 

.141 

.260 

.418 

.632 

.058 

.145 

.256 

.418 

.685 

.036 

.124 

.254 

7,647 

18,197 

102,598 

22,951 

10,166 

3,788 

2,889 

168,236 

7,328 

12,402 

89,842 

28,384 

12,071 

3,984 

4,562 

158,573 

0 

1,090 

6,516 

155 

7 

7,768 

.150 

.283 

1.357 

2.154 

2.505 

2.585 

.150 

.322 

1.396 

2.140 

2.505 

2.581 

.150 

.102 

1.174 

2.126 

20,357 

22,555 

16,358 

7,260 

5,824 

72,354 

20,289 

28,744 

19,281 

7,635 

9,214 

85,163 

463 

131 

11 

605 

i Calculated values are not rounded, to minimize rounding errors in subsequent calculations .. 2 Deep water table; no ground-water evapotranspiration from playa/bare-soil areas. 3 Supported by surface-water runoff; no ground-water component. 4 Exclusive of Ruby Lake/Marsh. 5 Ground-water component of open-water evaporation is included in Ruby Lake/Marsh category. 

8,686 

8,587 

5,541 

2,229 

1,643 

26,686 

(3) 

2,730 

29,043 

31,142 

21,899 

9,489 

7,467 

101,770 

(3) 

1,860 

8,636 28,925 

10,892 39,636 

6,551 25,832 

2,345 9,980 

2,558 11,772 

30,982 118,005 

203 

51 

4 

258 

0 

(2) 

666 

182 

15 

863 

Average 

cover 

0.069 

.141 

.256 

.419 

.663 

.048 

.141 

.261 

.419 

.656 

.067 

.140 

.259 

.415 

.654 

.077 

.120 

.249 

.374 

Area 

(acres) 

28 

4,367 

68,313 

44,723 

14,622 

5,280 

7,811 

14,637 

159,781 

27 

38,147 

103,189 

14,541 

6,988 

2,750 

2,594 

168,236 

166 

9,359 

91,595 

36,428 

14,044 

4,072 

2,909 

158,573 

0 

1 

6,504 

1,254 

9 

1 

7,769 

1989 

Evapotranspiration 

Annual 

average 

rate (feet) 

0.150 

.461 

1.361 

2.138 

2.506 

2.586 

.150 

.226 

1.359 

2.160 

2.506 

2.582 

.150 

.418 

1.350 

2.152 

2.502 

2.583 

.150 

.529 

1.131 

2.115 

2.460 

Summer Winter Annual 

(acre- (acre- (acrefeet) feet) feet) 

( 

22,025 

42,670 

23,273 

10,125 

15,789 

9,249 

16,242 

7,910 

3,107 

4,406 

(5} 

655 

31,274 

58,912 

31,183 

13,232 

20,195 

22,000 

4 113,882 440,914 177,451 

16,296 

14,315 

11,276 

5,273 

5,232 

52,392 

26,916 

35,606 

22,576 

7,790 

5,870 

98,758 

2,423 

1,018 

14 

1 

3,456 

... 

6,997 

5,449 

3,816 

1,618 

1,466 

19,346 

(3) 

5,722 

23,293 

19,764 

15,092 

6,891 

6,698 

77,460 

(3) 

1,404 

11,377 38,293 

13,570 49,176 

7,652 30,228 

2,396 10,186 

1,645 7,515 

36,640 136,802 

1,019 

401 

5 

0 

1,425 

0 

(2) 

3,442 

1,419 

19 

4,881 

y 
Table C18. Area and annual volume of precipitation in valleys of eastern Nevada study area 1 

Precipitation Average Area Volume Valley zone precipitation (acres) (acre-feet) (feet) 

Antelope Valley 10 0.833 77,236 64,363 

11 .917 67,628 61,992 

12 1.000 63,017 63,017 

13 1.083 16,784 18,183 

14 1.167 15,696 18,312 

15 1.250 6,567 8,208 

16 1.333 4,014 5,352 

17 1.417 1,679 2,378 

18 1.500 1,714 2,570 

19 1.583 827 1,309 

20 1.667 520 867 

Average precipitation 1.250 

Total 255,682 246,551 

Butte Valley 10 .833 138,603 115,502 

11 .917 101,873 93,384 

12 1.000 181,753 181,753 

13 1.083 55,129 59,723 

14 1.167 48,432 56,504 

15 1.250 27,002 33,752 

16 1.333 24,541 32,721 

17 1.417 13,829 19,591 

18 1.500 10,548 15,822 

19 1.583 8,045 12,738 

20 1.667 11,966 19,943 

21 1.750 5,877 10,284 

22 1.833 6,375 11,687 

23 1.917 4,803 9,206 

24 2.000 7,912 15,825 

25 2.083 1,803 3,756 

26 2.167 1,319 2,858 

27 2.250 1,198 2,696 

28 2.333 1,354 3,159 

Average precipitation 1.583 

Total 652,362 700,904 

Clover Valley 12 1.000 135,088 135,088 

13 1.083 37,760 40,907 

14 1.167 45,071 52,583 

15 1.250 11,508 14,385 

16 1.333 8,762 11,682 

17 1.417 6,409 9,079 

18 1.500 4,345 6,518 

19 1.583 4,624 7,322 

20 1.667 7,613 12,688 

21 1.750 1,922 3,364 

TABLE C18 C45 
Table C18. Area and annual volume of precipitation in valleys of eastern Nevada study area 1

-Continued 

Average ~ 

Precipitation Area Volume Valley zone precipitation (acres) (acre-feet) (feet) 

Clover Valley-Continued 22 1.833 . 2,925 5,362 

23 1.917 2,294 4,396 r 

24 2.000 3,213 6,426 

25 2.083 1,778 3,704 

26 2.167 1,353 2,932 

27 2.250 1,587 3,570 

28 2.333 1,598 3,728 

29 2.417 1,236 2,986 

30 2.500 1,885 4,713 

31 2.583 1,174 3,032 

32 2.667 2,233 5,955 

33 2.750 1,583 4,354 

34 2.833 1,925 5,454 

35 2.917 1,315 3,835 

36 3.000 711 2,132 

37 3.083 377 1,163 

38 3.167 555 1,757 

39 3.250 337 1,097 

40 3.333 935 3,117 

Average precipitation 2.167 

Total 292,116 363,329 

Goshute Valley 9 .750 30 22 

10 .833 263,098 219,247 

11 .917 93,149 85,387 

12 1.000 128,126 128,126 

13 1.083 32,499 35,207 

14 1.167 33,030 38,535 

15 1.250 19,352 24,190 

16 1.333 18,325 24,434 

17 1.417 8,334 11,807 

18 1.500 7,252 10,878 

19 1.583 3,390 5,368 

20 1.667 3,575 5,958 

21 1.750 605 1,060 

22 1.833 718 1,317 

23 1.917 365 700 

24 2.000 320 640 

Average precipitation 1.375 

Total 612,168 592,876 

Hot Creek Valley 6 .500 254,292 127,146 

7 .583 58,069 33,873 

8 .667 177,037 118,025 

9 .750 59,089 44,317 

10 .833 74,746 62,288 

C46 Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
Table C18. Area and annual volume of precipitation in valleys of eastern Nevada study area 1

-Continued 

Precipitation Average Area Volume Valley zone precipitation (acres) (acre-feet) (feet) 

Hot Creek Valley-Continued 11 0.917 10,580 9,698 

12 1.000 12,118 12,118 

13 1.083 2,098 2,273 

14 1.167 1,997 2,329 

15 1.250 1,964 2,455 

16 1.333 1,545 2,060 

17 1.417 1,581 2,240 

18 1.500 1,953 2,929 

19 1.583 863 1,366 

20 1.667 570 950 

Average precipitation 1.083 

Total 658,502 424,067 

Independence Valley 10 -.833 4,448 3,707 

11 .917 17,792 16,309 

12 1.000 202,825 202,825 

13 1.083 36,105 39,114 

14 1.167 35,579 41,509 

15 1.250 15,046 18,808 

16 1.333 16,401 21,868 

17 1.417 9,750 13,812 

18 1.500 10,082 15,123 

19 1.583 3,391 5,370 

20 1.667 6,493 10,821 

21 1.750 824 1,443 

22 1.833 615 1,127 

23 1.917 722 1,383 

24 2.000 598 1,196 

Average precipitation 1.417 

Total 360,671 394,415 

Jakes Valley 12 1.000 182,857 182,857 

13 1.083 26,996 29,245 

14 1.167 21,740 25,364 

15 1.250 9,822 12,278 

16 1.333 23,029 30,705 

17 1.417 2,676 3,790 

18 1.500 1,951 2,927 

19 1.583 821 1,299 

20 1.667 607 1,011 

Average precipitation 1.333 

Total 270,499 289,476 

Little Fish Lake Valley 8 .667 53,696 35,798 

9 .750 27,146 20,360' 

10 .833 114,403 95,336 

11 .917 24,972 22,891 

12 1.000 32,626 32,626 

TABLE C18 C47 
Table C18. Area and annual volume of precipitation in valleys of eastern Nevada study area 1

-Continued 

Precipitation Average Area Volume Valley precipitation zone (feet) (acres) (acre-feet) 

Little Fish Lake Valley-Continued 13 1.083 7,553 8,182 

14 1.167 4,288 5,003 

15 1.250 3,419 4,273 

16 1.333 2,507 3,343 ... 17 1.417 2,275 3,222 

18 1.500 3,597 5,396 

Average precipitation 1.083 

Total 276,482 236,430 

Little Smoky Valley 6 .500 218,599 109,299 

7 .583 61,432 35,835 

8 .667 123,577 82,385 

9 .750 122,435 91,826 

10 .833 127,189 105,991 

11 .917 25,497 23,372 

12 1.000 26,125 26,125 

13 1.083 4,796 5,196 

14 1.167 4,279 4,992 

15 1.250 3,923 4,904 

16 1.333 5,461 7,281 

17 1.417 5,745 8,139 

18 1.500 6,088 9,133 

19 1.583 2,023 3,203 

20 1.667 3,407 5,678 

Average precipitation 1.083 

Total 740,576 523,359 

Long Valley 10 .833 66,702 55,585 

11 .917 49,757 45,611 

12 1.000 109,778 109,778 

13 1.083 31,746 34,392 

14 1.167 67,412 78,648 

15 1.250 37,729 47,161 

16 1.333 29,724 39,631 

17 1.417 9,700 13,742 

18 1.500 8,909 13,363 

19 1.583 2,783 4,406 

20 1.667 2,010 3,350 

21 1.750 1,149 2,010 

22 1.833 872 1,599 

23 1.917 658 1,261 

24 2.000 915 1,830 

Average precipitation 1.417 

Total 419,844 452,367 

Newark Valley 6 .500 1,796 898 

7 .583 5,872 3,425 

8 .667 75,423 50,282 

9 .750 35,042 26,281 

10 .833 53,543 44,619 

C48 Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
Table C18. Area and annual volume of precipitation in valleys of eastern Nevada study area 1

-Continued 

Precipitation Average Area Volume Valley zone precipitation (acres) (acre-feet) (feet) 

Newark Valley-Continued 11 0.917 44,756 41,027 

12 1.000 139,558 139,558 

13 1.083 35,963 38,959 

14 1.167 29,337 34,227 

15 1.250 14,890 18,613 

16 1.333 14,000 18,667 

17 1.417 10,174 14,414 

18 1.500 9,918 14,877 

19 1.583 8,471 13,413 

20 1.667 8,972 14,953 

21 1.750 5,368 9,394 

22 1.833 4,551 8,344 

23 1.917 4,017 7,699 

24 2.000 4,776 9,551 

25 2.083 794 1,653 

26 2.167 759 1,644 

27 2.250 796 1,790 

28 2.333 506 1,182 

Average precipitation 1.417 

Total 509,282 515,470 

Railroad Valley 6 .500 378,759 189,379 

(northern part) 7 .583 155,268 90,572 

8 .667 191,821 127,882 

9 .750 107,689 80,767 

10 .833 129,850 108,208 

11 .917 85,128 78,034 

12 1.000 71,651 71,651 

13 1.083 44,336 48,031 

14 1.167 47,187 55,052 

15 1.250 31,883 39,853 

16 1.333 36,215 48,286 

17 1.417 16,411 23,249 

18 1.500 14,036 21,053 

19 1.583 11,156 17,664 

20 1.667 19,538 32,563 

21 1.750 5,865 10,264 

22 1.833 4,995 9,157 

23 1.917 4,239 8,125 

24 2.000 4,718 9,435 

25 2.083 1,727 3,598 

26 2.167 1,093 2,368 

27 2.250 2,308 5,194 

28 2.333 3,798 8,863 

Average precipitation 1.417 

Total 1,369,671 1,089,248 

TABLE C18 C49 
Table C18. Area and annual volume of precipitation in valleys of eastern Nevada study area 1

-Continued 

Precipitation Average Area Volume Valley zone precipitation (acres) (acre-feet) (feet) 

Ruby Valley 11 0.917 308 283 

12 1.000 161,087 161,087 

13 1.083 67,429 73,048 

14 1.167 123,654 144,263 

15 1.250 49,507 61,884 

16 1.333 50,472 67,296 

17 1.417 31,709 44,921 

18 1.500 27,042 40,563 

19 1.583 18,327 29,018 

20 1.667 16,631 27,719 

21 1.750 9,609 16,816 

22 1.833 7,561 13,861 

23 1.917 7,250 13,896 

24 2.000 7,047 14,093 

25 2.083 5,546 11,554 

26 2.167 5,201 11,270 

27 2.250 5,222 11,750 

28 2.333 6,922 16,152 

29 2.417 4,532 10,951 

30 2.500 4,352 10,880 

31 2.583 4,346 11,228 

32 2.667 6,722 17,926 

33 2.750 2,360 6,489 

34 2.833 2,115 5,992 

35 2.917 1,872 5,459 

36 3.000 2,754 8,263 

37 3.083 1,366 4,212 

38 3.167 1,583 5,014 

39 3.250 1,357 4,409 

40 3.333 4,433 14,776 

41 3.417 318 1,087 

42 3.500 168 588 

43 3.583 133 475 

Average precipitation 2.250 

Total 638,935 867,223 

Spring Valley 8 .667 106,811 71,208 

9 .750 72,758 54,568 

10 .833 248,999 207,498 

11 .917 107,803 98,820 

12 1.000 133,646 133,646 

13 1.083 68,709 74,434 

14 1.167 63,007 73,509 

15 1.250 46,419 58,024 

16 1.333 45,371 60,494 

17 1.417 29,512 41,809 

cso Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
Table C18. Area and annual volume of precipitation in valleys of eastern Nevada study area 1

-Continued 

Precipitation Average Area Volume Valley zone precipitation (acres) (acre-feet) (feet) 

Spring Valley-Continued 18 1.500 31,580 47,370 

19 1.583 16,305 25,817 

20 1.667 28,406 47,344 

21 1.750 6,818 11,932 

22 1.833 6,780 12,430 

23 1.917 6,280 12,037 

24 2.000 8,862 17,724 

25 2.083 5,073 10,569 

26 2.167 4,294 9,303 

27 2.250 4,912 11,052 

28 2.333 5,517 12,873 

29 2.417 4,795 11,588 

30 2.500 3,482 8,705 

31 2.583 3,588 9,269 

32 2.667 7,283 19,421 

Average precipitation 1.667 

Total 1,067,010 1,141,444 

Steptoe Valley 8 .667 134,239 89,493 

9 .750 111,476 83,607 

10 .833 228,925 190,770 

11 .917 76,121 69,778 

12 1.000 202,268 202,268 

13 1.083 82,523 89,400 

14 1.167 89,928 104,916 

15 1.250 50,044 62,555 

16 1.333 49,177 65,569 

17 1.417 41,810 59,231 

18 1.500 37,803 56,705 

19 1.583 21,133 33,461 

20 1.667 33,722 56,203 

21 1.750 11,579 20,264 

22 1.833 10,232 18,759 

23 1.917 8,298 15,905 

24 2.000 19,027 38,053 

25 2.083 6,937 14,452 

26 2.167 5,415 11,731 

27 2.250 5,459 12,282 

28 2.333 6,906 16,115 

29 2.417 2,238 5,407 

30 2.500 1,208 3,019 

31 2.583 1,813 4,683 

32 2.667 7,336 19,563 

Average precipitation 1.667 

Total 1,245,617 1,344,189 

TABLE C18 C51 
Table C18. Area and annual volume of precipitation in valleys of eastern Nevada study area 1

-Continued 

Precipitation Average Area Volume Valley precipitation zone (feet) (acres) (acre-feet) 

Tippett Valley 9 0.750 1,992 1,494 

10 .833 102,228 85,190 

11 .917 43,695 40,054 

12 1.000 24,271 24,271 

13 1.083 13,382 14,497 

14 1.167 15,448 18,023 

15 1.250 6,627 8,284 

16 1.333 5,013 6,684 

17 1.417 3,398 4,814 

18 1.500 2,699 4,049 

19 1.583 1,863 2,950 

20 1.667 958 1,596 

Average precipitation 1.208 

Total 221,574 211,906 

1 Calculated values are not rounded, to minimize rounding errors in subsequent calculations. 

C52 Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
Table C19. Precipitation areas and volumes for selected precipitation zones and 

estimated recharge in valleys of eastern Nevada study area 1 

Precipitation Weighted Area Precipitation Estimated 

average in zone Recharge recharge range precipitation in zone {acre-feet factor {acre-feet (inches) (inches) {acres) per year) per year) 

Antelope Valley 

10-11 0.872 144,863 126,355 .008 1,011 

12-15 1.055 102,064 107,720 .130 14,004 

16-19 1.410 8,233 11,609 .144 1,672 

20 1.667 520 867 .158 137 

Total 255,680 246,551 16,824 

Butte Valley 

10-11 .869 240,477 208,887 .008 1,671 

12-15 1.062 312,316 331,732 .130 43,125 

16-19 1.420 56,963 80,872 .144 11,646 

20-28 1.864 42,607 79,414 .158 12,547 

Total 652,363 700,905 68,989 

Clover Valley 

12-15 1.059 229,427 242,962 .130 31,585 

16-19 1.433 24,140 34,601 .144 4,983 

20-33 2.075 32,393 67,210 .158 10,619 

34-40 3.015 6,155 18,554 .626 11,615 

Total 292,115 363,327 58,802 

Goshute Valley 

9-11 .855 356,277 304,657 .008 2,437 

12-15 1.061 213,006 226,057 .130 29,387 

16-19 1.407 37,302 52,486 .144 7,558 

20-24 1.733 5,584 9,675 .158 1,529 

Total 612,169 592,875 40,911 

Hot Creek Valley 

6-7 .515 312,361 161,019 .000 0 

8-11 .729 321,452 234,328 .008 1,875 

12-15 1.055 18,176 19,175 .130 2,493 

16-19 1.447 5,942 8,595 .144 1,238 

20 1.667 570 950 .158 150 

Total 658,501 424,067 5,756 

Independence Valley 

10-11 .900 22,239 20,016 .008 160 

12-15 1.044 289,556 302,256 .130 39,293 

16-19 1.418 39,624 56,173 .144 8,089 

20-24 1.726 9,251 15,970 .158 2,523 

Total 360,670 394,415 50,065 

Jakes Valley 

12-15 1.034 241,415 249,744 .130 32,467 

16-19 1.360 28,476 38,722 .144 5,576 

20 1.667 607 I ,011 .158 160 

Total 270,498 289,477 38,203 

TABLE C19 C53 
Table C19. Precipitation areas and volumes for selected precipitation zones and 

estimated recharge in valleys of eastern Nevada study area 1

-Continued 

Precipitation Weighted Area Precipitation Estimated 

average in zone Recharge recharge range precipitation in zone (acre-feet factor (acre-feet (inches) (inches) (acres) per year) per year) 

Little Fish Lake Valley 

8-11 .792 220,218 174,385 .008 1,395 

12-15 1.046 47,885 50,084 .130 6,511 

16-18 1.428 8,379 11,961 .144 1,722 

Total 276,482 236,430 9,628 

Little Smoky Valley 

6-7 .518 280,030 145,134 .000 0 

8-11 .761 398,698 303,574 .008 2,429 

12-15 1.054 39,123 41,217 .130 5,358 

16-19 1.437 19,317 27,756 .144 3,997 

20 1.667 3,407 5,678 .158 897 

Total 740,575 523,359 12,681 

Long Valley 

10-11 .869 116,460 101,196 .008 810 

12-15 1.095 246,665 269,979 .130 35,097 

16-19 1.392 51,115 71,143 .144 10,245 

20-24 1.793 5,604 10,050 .158 1,588 

Total 419,844 452,368 47,740 

Newark Valley 

6-7 .564 7,668 4,323 .000 0 

8-11 .777 208,764 162,209 .008 1,298 

12-15 1.053 219,748 231,357 .130 30,076 

16-19 1.442 42,564 61,371 .144 8,837 

20-28 1.841 30,538 56,210 .158 8,881 

Total 509,282 515,470 49,092 

Railroad Valley (northern part) 

6-7 .524 534,026 279,952 .000 0 

8-11 .768 514,489 394,890 .008 3,159 

12-15 1.100 195,057 214,587 .130 27,896 

16-19 1.417 77,818 110,253 .144 15,876 

20-28 1.855 48,281 89,567 .158 14,152 

Total 1,369,671 1,089,249 61,083 

Ruby Valley 

11 0.917 308 283 .008 2 

12-15 1.096 401,677 440,282 .130 57,237 

16-19 1.425 127,550 181,797 .144 26,179 

20-33 2.086 93,302 . 194,587 .158 30,745 

34-43 3.123 16,099 50,276 .626 31,473 

Total 638,936 867,225 145,636 

Spring Valley 

8-11 .806 536,370 432,094 .008 3,457 

12-15 1.089 311,781 339,613 .130 44,150 

16-19 1.429 122,768 175,490 .144 25,271 

20-32 2.022 96,091 194,247 .158 30,691 

Total 1,067,010 1,141,444 103,569 

C54 Chapter C. Regional Ground-Water Budgets and Ground-Water Flow, Eastern Nevada 
Table C19. Precipitation areas and volumes for selected precipitation zones and 

estimated recharge in valleys of eastern Nevada study area 1-Continued 

Precipitation Weighted Area Precipitation Estimated 

average in zone Recharge recharge range precipitation in zone (acre-feet factor (acre-feet (inches) (inches) (acres) per year) per year) 

Steptoe Valley 

8-11 .787 550,762 433,649 .008 3,469 

12-15 1.081 424,764 459,140 .130 59,688 

16-19 1.434 149,923 214,965 .144 30,955 

20-32 1.968 120,169 236,437 .158 37,357 

Total 1,245,618 1,344,191 131,469 

Tippett Valley 

9-11 .857 147,915 126,737 .008 1,014 

12-15 1.090 59,728 65,075 .130 8,460 

16-19 1.426 12,973 18,496 .144 2,663 

20 1.667 958 1,596 .158 252 

Total 221,574 211,904 12,389 

1 Calculated values are not rounded, to minimize rounding errors in subsequent calculations. 

TABLE C19 C55 
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