Prepared in cooperation with

CHURCHILL COUNTY

Evaluation of U.S. Geological Survey Monitoring-Well 

Network and Potential Effects of Changes in Water Use, 

Newlands Project, Churchill County, Nevada

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2004–5246
(Back of Cover)
Evaluation of U.S. Geological Survey Monitoring-Well 

Network and Potential Effects of Changes in Water Use, 

Newlands Project, Churchill County, Nevada

By Douglas K. Maurer, Ralph L. Seiler, and Sharon A. Watkins

U.S. GEOLOGICAL SURVEY

Carson City, Nevada

2004

Prepared in cooperation with

CHURCHILL COUNTY

Scientific Investigations Report 2004–5246
U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

CHARLES G. GROAT, Director

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

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

For additional information Copies of this report can be

contact: purchased from:

District Chief U.S. Geological Survey 

U.S. Geological Survey Information Services

333 West Nye Lane, Room 203 Building 810

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

Denver, CO 80225–0286

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

http://nevada.usgs.gov
 iii

CONTENTS

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

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

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

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

Physical and Hydrologic Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Methods Used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Evaluation of USGS Monitoring-Well Network. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Evaluation of the Effects of Changes in Water Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Changes in Ground-Water Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Changes in Ground-Water Quality. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Suggestions for Improvement of the USGS Monitoring-Well Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

References Cited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

FIGURES

1. Map showing location of Carson River basin, Carson Desert, Lahontan Valley, and nearby geographic features . . . . . . . . . . . . . 3

2. Map showing location of irrigated lands of the Carson Division of the Newlands Project, general direction of shallow

ground-water flow, and geographic features of Lahontan Valley. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3. Map showing approximate location of irrigated land, land where water-rights have been purchased, location of 

monitoring wells, and wells where water-level declines from the early 1990’s to 2003 are 1 foot or less and greater

than 1 foot. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

4. Graphs showing the distance of monitoring wells from active canals or ditches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

5. Graphs showing the distance of monitoring wells from irrigated land . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

6. Graph showing annual volume of water released from Lahontan Reservoir, 1967–2003 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

7. Graph showing relation between water-level change between 1992–95 and 2003 and distance from canals . . . . . . . . . . . . . . . . . 16

8. Graph showing changes in specific conductance at selected wells, 1988–2003 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

9. Map showing location of monitoring wells where continued monitoring would be useful, and where monitoring

could be discontinued. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

TABLES

1. Distance and direction between monitoring wells and nearest canal, ditch, or reservoir and nearest irrigated field in 2003 . . . 9

2. Summary of acreage removed from irrigation near 25 monitoring wells. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

3. Changes in water levels at selected wells from the early 1990’s and mid-1970’s to 2003. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
iv 

APPENDIXES 

A. Monitoring well measurement frequency 1998–2003, site identifier, location, and well construction data. . . . . . . . . . . . . . . . . . . . . 24

B. Truckee-Carson Irrigation District serial numbers of parcels near monitoring wells and summary of parcel size, 

average distance of parcel from well, gradient direction, irrigation history for water years 1992 through 2003, and 

irrigation prior to 1992 for parcels not irrigated 1992–2003. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

C. Water-level hydrographs for monitoring wells for period of record at each well . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

D. Summary of water-quality analyses for samples taken from monitoring wells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

CONVERSION FACTORS AND VERTICAL DATUM 

Multiply By To obtain

acre 4,047 square meter

acre foot (acre-ft) 0.001233 cubic hectometer

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

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

foot (ft) 0.3048 meter

inch (in.) 25.4 millimeter

inch per year (in/yr) 25.4 millimeter per year

mile (mi) 1.609 kilometer

square mile (mi2) 2.590 square kilometer

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

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

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

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

Metric water-quality units used in this report:

μg/L, micrograms per liter

μS/cm, microsiemens per centimeter at 25°C

mg/L, milligrams per liter
Evaluation of U.S. Geological Survey Monitoring-Well 

Network and Potential Effects of Changes in Water Use, 

Newlands Project, Churchill County, Nevada

by Douglas K. Maurer, Ralph L. Seiler, and Sharon A. Watkins 

Abstract

Domestic wells tapping shallow ground water are an 

important source of potable water for rural residents of 

Lahontan Valley. For this reason, the public has expressed 

concern over the acquisition of water rights directed by Public 

Law 101-618. The acquisition has resulted in removal of land 

from irrigation, which could cause shallow domestic wells to 

go dry and adversely affect shallow ground-water quality. 

Periodic water-level measurements and water-quality

sampling at a monitoring-well network developed by the U.S. 

Geological Survey (USGS) provided data to evaluate the potential effects of changes in water use. The USGS, in cooperation 

with Churchill County, analyzed these data and the monitoringwell network to determine if the network provides an adequate 

means to measure the response of the shallow aquifer to 

changes in water use, and to determine if measurable changes 

have taken place. 

To evaluate the USGS monitoring-well network, wells 

were characterized by their distance from active canals or 

ditches, and from currently (2003) or formerly irrigated land. 

An analysis of historical data showed that about 9,800 acres of 

land have been removed from irrigation, generally from the late 

1990's to 2003. Twenty-five wells in the network are within 

about 1 mile of fields removed from irrigation. Of the 25 wells, 

13 are within 300 feet of canals or ditches where seepage maintains stable water levels. The 13 wells likely are not useful for 

detecting changes caused by reductions in irrigation. The 

remaining 12 wells range from about 400 to 3,800 feet from the 

nearest canal and are useful for detecting continued changes 

from current reductions in irrigation. The evaluation showed 

that of the 75 wells in the network, only 8 wells are likely to be 

useful for detecting the effects of future (after 2003) reductions 

in irrigation.

Water levels at most of the monitoring wells near irrigated 

land have declined from 1998 to 2003 because of drought conditions and below normal releases from Lahontan Reservoir. 

This period coincides with the period of irrigation reductions, 

tending to mask declines directly caused by the reductions. It is 

likely that seepage from the diffuse network of canals and 

ditches in Lahontan Valley also masks declines caused by 

reductions in irrigation. In addition, the limited number of 

monitoring wells near land removed from irrigation, yet more 

than 300 feet from an active canal, does not allow a valid statistical correlation between reductions in irrigation and waterlevel declines. 

Water-level declines between the last two periods of below 

normal releases from Lahontan Reservoir, 1992–95 and 2000–

2003, ranged from 0.4 to 4.2 feet at 11 monitoring wells near 

land removed from irrigation. The maximum observed water 

declines were about 2 to 4 feet in three wells in the southern part 

of Lahontan Valley. The three wells are near or surrounded by 

more than 1,000 acres removed from irrigation, are now more 

than 3,600 feet from continued irrigation, and are within 300 

feet of a canal with greatly decreased use. Water levels generally rose in monitoring wells near Stillwater, Nevada, even 

though large amounts of nearby land were removed from irrigation. This was likely caused by conditions in 2003 that were not 

as dry as those in the early 1990's and additional seepage from 

the increased use and stage of canals for delivery of water to 

wetland areas.

Five wells have been sampled since the late 1990's and two 

wells have been sampled since 2000 to evaluate long-term 

changes in water quality. Specific conductance of water sampled from these wells was used to evaluate changes in water 

quality. One well shows a large decline in specific conductance 

that may be related to changes in water use. In three other wells 

that showed a decrease in specific conductance it is uncertain if 

the decrease was related to changes in water use because samples were not collected shortly before and after the time land 

was removed from irrigation. 

Additional wells would improve the monitoring-well network. The best locations for the new wells would be near lands 

where reductions in irrigation will likely occur, yet distant from 

irrigation canals or ditches. Water-level measurements and 

water-quality samples could be obtained prior to removal of 

irrigation, and continue after removal of irrigation. During 

future periods of greater releases from Lahontan Reservoir, 

continued monitoring of wells near reductions in irrigation 

would show if water levels continue to decline and the magnitude of total decline.
2 Evaluation of USGS Monitoring-Well Network and Potential Effects of Changes in Water Use, Newlands Project

Introduction

From 1903 to 1915, the Bureau of Reclamation (BOR) 

constructed the Truckee Canal to divert water from the Truckee 

River and Lahontan Dam on the Carson River for development 

of the Newlands Project, one of the first reclamation projects in 

the Nation (fig. 1; Bureau of Reclamation, 1988). Shortly after 

construction was completed, delivery of water began to fields in 

Lahontan Valley (the name generally applied to the irrigated 

part of the Carson Desert). The Newlands Project stores water 

from the Carson and Truckee Rivers for irrigation of about 

56,000 acres of land (average 1984–90) in Lahontan Valley 

(figs. 1 and 2). These irrigated lands form the Carson Division 

of the Newlands Project.

The construction of water-storage reservoirs, the addition 

of an extensive system of canals and drains, and the application 

of irrigation water to fields have altered ground-water levels 

and ground-water quality in Lahontan Valley (Seiler and 

Allander, 1993, p. 12–13; Lico and Seiler, 1994, p. 63). Shallow 

ground water in Lahontan Valley varies greatly in quality 

(Glancy, 1986, p. 41), and generally degrades towards the north, 

east, and south from the center of the valley (Lico and Seiler, 

1994, p. 31). Poor-quality ground water discharges to deep open 

drains and is carried to wetlands at Carson Lake and the Stillwater Wildlife Management Area (fig. 2). Delivery of poorquality water containing high concentrations of trace elements 

to these wetlands has resulted in habitat degradation and accumulation of potentially toxic concentrations of arsenic and selenium in the biota (Hoffman and others, 1990). 

Domestic wells tapping shallow ground water are currently (2003) an important source of potable water for rural residents of Lahontan Valley and, consequently, the quality and 

quantity of shallow ground water are important public issues. 

The Truckee-Carson-Pyramid Lake Water Rights Settlement 

Act of 1990 (Public Law 101-618) directed the U.S. Fish and 

Wildlife Service (USFWS) to acquire water for wetland areas in 

the Carson Desert. The public has expressed concern that acquisition of water rights and delivery of water directly to the wetland areas could cause shallow domestic wells to go dry and 

adversely affect shallow ground-water quality. 

In 1992, the USGS, in cooperation with the USFWS, 

developed a network of 126 monitoring wells screened in the 

shallow and intermediate aquifers in Lahontan Valley and 

began periodic water-level measurements (Seiler and Allander, 

1993, p. 2). From 1994 to 2003, in cooperation with Churchill 

County, water-levels were measured by the USGS at 75 monitoring wells to determine the effects of changes in water use. 

Also in cooperation with Churchill County, water-quality sampling and analysis of five wells began in 1998 from one to three 

times a year, generally during the irrigation and non-irrigation 

season. 

As Lahontan Valley becomes increasingly urbanized, an 

additional concern is that shallow ground-water quality may 

degrade from development in residential areas where septic 

tanks will be utilized. In 2000, two wells were installed in an 

area currently covered by sparse native vegetation but planned 

for subdivision into 1-acre lots serviced by individual wells and 

septic tanks. The two monitoring wells were sampled once or 

twice yearly. 

Water-level and water-quality data collected from the 

USGS monitoring-well network, and the network itself, need to 

be evaluated to determine whether the locations and distribution 

of monitoring wells provide a reasonable means to measure the 

response of the shallow aquifer to changes in land and water 

use, and to determine whether measurable changes have taken 

place. In 2003 the USGS, in cooperation with Churchill County, 

began an evaluation of the network to answer these questions. 

Purpose and Scope

The purpose of this report is to present an evaluation of the 

adequacy of the current monitoring-well network in Lahontan 

Valley for detecting water-level and water-quality changes 

caused by changes in water use, and to present an analysis of 

measured changes in water levels and water quality. The 75 

monitoring wells in the network are characterized by their distance from canals or ditches, and distance from currently or formerly irrigated lands. The acreage and irrigation history of land 

where water-rights have been purchased was determined for the 

period 1992–2003. The characterizations were used to evaluate 

the network and propose changes in the network. 

Water levels measured at 75 wells from 1974 to 2003 and 

concentrations of major inorganic constituents and nutrients 

from seven wells sampled from 1988 to 2003 are presented. 

Water level changes were evaluated by comparison with water 

levels measured in the early 1990's, the last period of below normal releases from Lahontan Reservoir. Specific conductance 

changes were evaluated graphically. Linear regressions were 

made to examine the relation between water-level decline and 

the acreage and distance of land removed from irrigation. Measured changes in water levels and quality are described in terms 

of the magnitude of water-level decline, specific conductance, 

distance from and acreage of land removed from irrigation, and 

distance from active canals or ditches and continued irrigation.

Acknowledgments

The authors thank Richard Grimes and James Parden of 

the USFWS, and Ruth Danner of Nevada State Lands for providing information on the location of lands where water rights 

have been purchased; Steven Munts and Roger LeSueur of the 

Bureau of Reclamation, Fallon Field Office, for providing 

access to aerial photographs of irrigated lands and irrigation history; and David Overvold of the Truckee-Carson Irrigation District (TCID) for providing information on the use of irrigation 

canals and ditches. 
Introduction 3

Figure 1. Location of Carson River basin, Carson Desert, Lahontan Valley, and nearby geographic features.
4 Evaluation of USGS Monitoring-Well Network and Potential Effects of Changes in Water Use, Newlands Project

4000

4000

4000

5000

4000

4200

5000

4000

4000

5000

5000

5000

4000

4000

4200

5000

4200

5000

4000

3990

3990

3890

3980

3970

3960

3950

3940

3930

3920

3920

3910

3910

3900

3900

3900

CARSON SINK CARSON SINK ARSON SINK

STILLWATER

WILDLIFE

MANAGEMENT

AREA

STILLWATER

WILDLIFE

MANAGEMENT

AREA

STILLWATER

WILDLIFE

MANAGEMENT

AREA

STILLWATER STILLWATER STILLWATER

MARSH

Fallon

Stillwater Stillwater tillwater

RATTLESNAKE

HILL

RATTLESNAKE

HILL RATTLESNAKE

HILL

Stillwater

Point 

Reservoir

Stillwater

Point 

Reservoir

Stillwater

Point 

Reservoir

LAHONTAN MOUNTAINS LAHONTAN MOUNTAINS LAHONTAN MOUNTAINS

STILLWATER STILLWATER STILLWATER

RANGE

BUNEJUG MOUNTAINSBUNEJUG MOUNTAINSBUNEJUG MOUNTAINS

HOT SPRINGS MOUNTAINSHOT SPRINGS MOUNTAINSHOT SPRINGS MOUNTAINS

LAHONTAN LAHONTAN LAHONTAN

VALLEY

SALT

WELLS

BASIN Salt Wells Salt Wells alt Wells

WHITE THRONE

MOUNTAINS

WHITE THRONE

MOUNTAINS

WHITE THRONE

MOUNTAINS

Carson

Lake

Carson

Lake

Carson

Lake

Soda

Lake

Soda Lake Soda

Lake Old River

Reservoir

Old River Reservoir Old River

Reservoir

Sheckler

Reservoir

Sheckler Reservoir Sheckler

Reservoir

Lyon

County

Lyon CountyLyon

County Churchill

County

Churchill

County

Churchill

County

Carson

Carson

River

River

UPSAL

HOGBACK

UPSAL

HOGBACK

UPSAL

HOGBACK

South

Branch

NAS,

Fallon

NAS, FallonNAS,

Fallon

Roads and hydrology from U.S. Geological Survey digital data,

1:100,000, 1979–80. Hypsography and water bodies from

U.S. Geological Survey digital data 1:250,000, 1971

Universal Transverse Mercator Projection, Zone 11

39o45'

119o00' 118o45' 118o30'

39o30'

39o15'

0

0

5

5

10 MILES

10 KILOMETERS

R. 27 E. R. 28 E. R. 29 E. R. 30 E. R. 31 E. R. 32 E.

T.

22

N.

T.

21

N.

T.

20

N.

T.

19

N.

T.

18

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17

N.

T.

16

N.

EXPLANATION

Discharging playa—From Glancy and Katzer (1975, pl. 1)

Phreatophytes—From Glancy and Katzer (1975, pl. 1)

Irrigated land, 1984–90—From Bureau of Reclamation 

 digital data (Charles Johnson, Bureau of Reclamation, 

 written commun., 1993)

Wetlands

Hydrographic area boundary—From Rush (1968)

Topographic contour—Shows altitude of land surface. 

 Contour interval, 1,000 feet, with supplemental contour 

 at 4,200 feet. Datum is sea level

Water-level contour—Shows altitude of water table, 1992. 

 Modified from Seiler and Allander (1993, pl. 1). Dashed 

 where uncertain. Contour interval, 10 feet. Datum is sea level

General direction of ground-water flow—From Seiler and 

 Allander (1993, pl. 1)

3990

4000

Figure 2. Location of irrigated lands of the Carson Division of the Newlands Project, general direction of shallow ground-water

flow, and geographic features of Lahontan Valley.
Physical and Hydrologic Setting 5

Physical and Hydrologic Setting

The physical and hydrologic setting of Lahontan Valley 

has been dominated by the Carson River over geologic time. 

During Pleistocene time (2 million to 10 thousand years ago), 

lakes formed in the Carson Desert with water levels rising and 

falling to complete dryness several times under the influence of 

changing glacial climates (Axelrod, 1956; Morrison, 1964). 

During high stands, the lakes coalesced to form ancient Lake 

Lahontan having a maximum depth of more than 500 ft in the 

Carson Desert (Davis, 1978, p. 2; Morrison, 1991, p. 288). During high stands of Lake Lahontan, thick clay beds were deposited in the deeper parts of Lake Lahontan, deltas were formed 

on the western side of the valley where the Carson River entered 

the lake, and sand and gravel beaches and bars were formed by 

wave action along the shorelines (Morrison, 1964, p. 28–71). 

During interglacial periods when Lake Lahontan was dry, large 

sand-dune and sand-sheet complexes covered much of the valley floor and the Carson River meandered across the valley 

floor forming relict river channels which are now buried. As 

lake levels rose and fell, these depositional environments 

moved back and forth across the valley floor, creating a complex mixture of Quaternary sediments more than 2,500-ft thick 

(Maurer and others, 1996, pl. 1).

Since construction of Lahontan Reservoir, irrigation with 

surface-water has dominated the hydrologic system. The outflow from Lahontan Reservoir has averaged about 367,000 

acre-ft/yr from 1967 to 2002 (Berris and others, 2003, p. 201). 

The irrigation season is generally from April through October, 

during which an average of about 190,000 acre-ft/yr is delivered 

to 1,500 farm headgates through about 340 mi of canals and 

lateral ditches. About 350 mi of drains route return flow and 

ground-water seepage to wetland areas (Maurer and others, 

1996, p. 16 and 24). Streamflow in Lahontan Valley not used 

for irrigation, and streamflow in drains, flows north to the 

Carson Sink, northeast to wetlands in the Stillwater Wildlife 

Management Area, or south to the Carson Lake wetlands. Water 

released from Lahontan Reservoir is generally of good quality 

with dissolved-solids concentrations of about 200 mg/L (Lico 

and Seiler, 1994, p. 26). 

Alfalfa is the main irrigated crop in the valley, along with 

pasture, and some cereal and vegetable crops. Cottonwood trees 

are abundant near homes and ranches in the irrigated part of the 

valley, willows line many of the canals, and cattails fill most 

drains. Non-irrigated areas are sparsely vegetated with greasewood, rabbitbrush, saltgrass, and marsh grasses. The Carson 

Sink is largely barren.

The rapidly growing city of Fallon is the major population 

center in the area. The population of Fallon, including Naval Air 

Station Fallon, increased from about 3,000 in the early 1970's 

(Glancy, 1986, p. 27) to 8,800 in 2000 (U.S. Census Bureau, 

2004a). About 15,000 people also live in the surrounding unincorporated areas of the county (U.S. Census Bureau, 2004b). 

Agriculture is the major economic base in the area, followed by 

employment at the Naval Air Station. 

The floor of Lahontan Valley is a relatively flat plain, sloping from about 3,960 ft above sea level near Fallon to about 

3,870 ft near the Carson Sink (fig. 1). Several low-lying mountain ranges surround the valley on the north, south, and west 

rising to about 5,500 ft in altitude, and the Stillwater Range 

bounds the valley on the east, rising to 8,800 ft in altitude 

(fig. 2).

Lahontan Valley is in the rain shadow of the Sierra Nevada 

to the west and received an average 5.3 in/yr of precipitation 

from 1971–2000 (National Oceanic and Atmospheric Administration, 2002, p. 12). Average maximum temperatures are about 

90o F in July and August, and average minimum temperatures 

are about 17o F in December and January (National Oceanic and 

Atmospheric Administration, 2002, p. 8). Open-water evaporation is about 5 ft/yr (Bureau of Reclamation, 1987, p. 1-7).

Previous studies in the area provide a general understanding of the aquifer systems in the study area and the large-scale 

direction of ground-water flow. However, the complex lithology of Quaternary sediments and the complex surface-water 

distribution system of canals and drains make a detailed understanding difficult without site-specific investigations. Studies 

have shown that the direction of ground-water flow, at a small 

scale, can vary greatly and is controlled by local irrigation practices and the location of canals and drains (Lico and others, 

1986, p. 93; Lico, 1992, p. 8).

Glancy (1986) delineated three sedimentary aquifers in the 

Carson Desert: the shallow, intermediate, and deep aquifers. He 

also provided the first detailed description of the basalt aquifer, 

the sole source of water for the city of Fallon, the Naval Air Station, and the Fallon Paiute-Shoshone Tribe. The basalt aquifer 

and surrounding sedimentary aquifers are described in detail by 

Maurer and Welch (2001), and the shallow aquifer and effects 

of changes in water use are described by Seiler and Allander 

(1993) and Herrera and others (2000). The geohydrology and 

water budget of Lahontan Valley are described in detail by 

Maurer and others (1996),

On the basis of water hardness, Glancy (1986, p. 41) 

defined the shallow aquifer to extend from the water table to a 

depth of 50 ft below land surface. The shallow aquifer is an 

unconfined aquifer. Prior to the Newlands Project, the depth to 

water in the shallow aquifer was 5 to 10 ft below land surface 

within 1 to 2 mi of the main channels of the Carson River, 

increasing to over 25 ft in areas between the river channels 

(Seiler and Allander, 1993, p. 13). After operation of the Newlands Project, infiltration from the canal system and beneath 

irrigated land caused water levels to rise more than 15 ft in some 

parts of the shallow aquifer, while installation of drains caused 

water levels to decline in other areas, creating a more uniform 

depth to water (Seiler and Allander, 1993, p. 10–13). Presently 

(2003), the depth to water beneath much of the valley floor is 

from 5 to 10 ft below land surface (Seiler and Allander, 1993, 

p. 13), and likely is controlled by the depth of drains which were 

excavated to depths of 4 to 8 ft below land surface (Herrera and 

others, 2000, p. 8 and 10). 
6 Evaluation of USGS Monitoring-Well Network and Potential Effects of Changes in Water Use, Newlands Project

The hardness in ground water in the shallow aquifer is 

greater than 70 mg/L (as CaCO3), which is considered moderately hard (Hem, 1989, p. 159). The shallow aquifer is characterized by abrupt changes in lithology and ground-water quality 

over short distances (Glancy, 1986, p. 41). The dissolved-solids 

concentration of water in the shallow aquifer is generally 

between 200 and 600 mg/L beneath the west-central part of the 

valley, increasing to more than 10,000 mg/L about 10 mi north, 

east, and south of Fallon (Lico and Seiler, 1994, p. 33). The stable isotope composition of water in the shallow aquifer is consistent with recharge by water applied for irrigation (Welch and 

others, 1997, p. A28 and A31). 

Maurer and Welch (2001, p. 35) observed an abrupt 

change in the stable isotope composition at a depth of 50 ft, 

which suggests that water in the intermediate aquifer near the 

center of Lahontan Valley was recharged prior to construction 

of Lahontan Reservoir. Ground water from wells deeper than 

50 ft is distinctly lighter in its isotopic composition than ground 

water from wells shallower than 50 ft. This indicates that, near 

the center of the valley, recharge from the Carson River is 

restricted to the upper 50 ft (the shallow aquifer) under the current hydrologic regime. On the western side of Lahontan Valley, near to and west of Soda Lake, recharge from the Carson 

River to the intermediate aquifer has occurred to depths of over 

100 ft (Lico and Seiler, 1994, p. 16). 

The intermediate aquifer extends from a depth of 50 ft 

below land surface to between 500 and 1,000 ft. The intermediate aquifer is a confined aquifer with water levels in wells rising 

to within 10 to 40 ft of land surface.The lower limit of its extent 

is the depth of sediments bearing fresh water near the basalt 

aquifer (Glancy, 1986, p. 51). However, the vertical extent of 

fresh water in the intermediate aquifer is poorly known because 

only 3 wells slightly more than 500-ft deep and one well 1,700-

ft deep are known to have been sampled (Whitney, 1994, table 

36; Lico and Seiler, 1994, p. 36). Beneath the west-central part 

of the valley, the intermediate aquifer is characterized by 

relatively fresh, soft water with hardness generally less than 

25 mg/L (Glancy, 1986, p. 56). The dissolved-solids concentration of water in the intermediate aquifer ranges from 200 to 

600 mg/L beneath the west-central part of the valley, and 

increases to more than 1,000 mg/L about 8 mi north of Fallon, 

about 5 mi east of Fallon, and about 6 mi south of Fallon (Lico 

and Seiler, 1994, p. 33). 

The deep aquifer is defined to extend from 500 to 1,000 ft 

below land surface to depths of several thousand feet, and is 

thought to be mainly non-potable (Glancy, 1986, p. 51 and 60). 

Little is known about its water quality because only one well in 

the deep aquifer (1,700-ft deep) is known to have been sampled 

(Lico and Seiler, 1994, p. 36). 

Glancy (1986) delineated the extent of the basalt aquifer 

using lithologic descriptions from driller's logs and surface 

electrical-resistivity soundings. Maurer and Welch (2001) used 

additional driller's logs and seismic reflection soundings to generally confirm the extent and configuration of the basalt aquifer 

as delineated by Glancy (1986). The aquifer is an asymmetrical, 

mushroom-shaped body of basalt exposed at Rattlesnake Hill 

with the bulk of the basalt surrounded by the sedimentary aquifers (Glancy, 1986, p. 13–14). In plan view, the basalt aquifer is 

about 10 mi long in a southwest to northeast direction and about 

4 mi wide. Driller's logs show the basalt is 400–600 ft below 

land surface about 2 mi southwest of Rattlesnake Hill, and 

about 200–300 ft below land surface 5–7 mi northeast of Rattlesnake Hill. 

Ground water in the shallow aquifer flows from west to 

east (fig. 2). North of Fallon, ground-water flow is generally to 

the northeast toward the Carson Sink and south of Fallon, flow 

is southeastward toward Carson Lake (Seiler and Allander, 

1993, pl. 1; Glancy, 1986, p. 42). Water-level fluctuations in the 

shallow aquifer show that it is recharged by infiltration of surface water during the irrigation season (Glancy, 1986, p. 39). 

Water-level contours for wells screened in the intermediate 

aquifer show that ground-water flows in directions similar to 

the shallow aquifer (Glancy, 1986, p. 53). The shallow aquifer 

has the potential to recharge the intermediate aquifer in the 

west-central part of the valley as shown by higher water levels 

in the shallow aquifer than in the intermediate aquifer (Glancy, 

1986, p. 54). Isotopic data presented earlier indicates, however, 

that recharge of present day Carson River water to the intermediate aquifer is only occurring in the western part of Lahontan 

Valley. Elsewhere in the valley, ground-water flow is upward 

from the intermediate to the shallow aquifer where ground 

water is discharged to irrigation drains, by evapotranspiration of 

irrigated crops and natural vegetation, or by evaporation from 

bare soil (Glancy, 1986, p. 54). 

Methods Used

The data-collection/monitoring-well network was developed in 1992 and consists of 75 wells; a combination of monitoring wells installed for previous studies in the area, generally 

of 1.5- to 2-in. diameter, and domestic wells of larger diameter 

(fig. 3; app. A). Water-level and water-quality data have been 

collected at some wells since the mid-1970's, at other wells 

installed in the mid-1980's for a regional USGS water-quality 

study (Whitney, 1994) and for Department of Interior irrigation-drainage studies (Rowe and others, 1991), and at others 

installed in 1992 for a study of the shallow aquifer (Seiler and 

Allander, 1993). Most wells are screened in the shallow aquifer 

(less than 50 ft in depth); however, 11 wells screened in the 

intermediate aquifer have been included in the network to provide information on potential changes at greater depth. Waterlevel measurements are made with a standard 1⁄4-inch steel tape 

or electric tape and referenced to a measuring point and land 

surface near the well head. The measurements are considered 

accurate to the nearest 0.01 ft for steel tapes and 0.1 ft for electric tapes. 

The frequency of water-level measurements at the network 

wells has changed over time. From 1992 to 1998, selected wells 

were measured every two weeks while other wells were measured three times a year (before, during, and after the irrigation 

season). To reduce monitoring costs, in 1998 the network was 

divided into wells with monthly, quarterly, and annual measurement frequencies (app. A). Wells measured annually are measured in late September at the end of the irrigation season. Wells 

1 and 55 were plugged in 2000 and 2003, respectively. 
Methods Used 7

4000

4000

4000

5000

4000

4200

5000

4000

4000

5000

5000

5000

4000

4000

4200

5000

4200

5000

CARSON SINK CARSON SINK ARSON SINK

STILLWATER

WILDLIFE

MANAGEMENT

AREA

STILLWATER

WILDLIFE

MANAGEMENT

AREA

STILLWATER

WILDLIFE

MANAGEMENT

AREA

STILLWATER STILLWATER STILLWATER

MARSH

Fallon

Stillwater Stillwater tillwater

RATTLESNAKE

HILL

RATTLESNAKE

HILL RATTLESNAKE

HILL

Stillwater

Point 

Reservoir

Stillwater

Point Reservoir

Stillwater

Point 

Reservoir

LAHONTAN MOUNTAINS LAHONTAN MOUNTAINS LAHONTAN MOUNTAINS

STILLWATER STILLWATER STILLWATER

RANGE

BUNEJUG MOUNTAINSBUNEJUG MOUNTAINSBUNEJUG MOUNTAINS

HOT SPRINGS MOUNTAINSHOT SPRINGS MOUNTAINSHOT SPRINGS MOUNTAINS

LAHONTAN LAHONTAN LAHONTAN

VALLEY

SALT

WELLS

BASIN Salt Wells Salt Wells alt Wells

WHITE THRONE

MOUNTAINS

WHITE THRONE

MOUNTAINS

WHITE THRONE

MOUNTAINS

Carson

Lake

Carson

Lake

Carson

Lake

Soda

Lake

Soda Lake Soda

Lake Old River

Reservoir

Old River

Reservoir

Old River

Reservoir

Lyon

County

Lyon CountyLyon

County Churchill

County

Churchill

County

Churchill

County

Carson

Carson

River

River

UPSAL

HOGBACK

UPSAL

HOGBACK

UPSAL

HOGBACK

South

Branch

NAS,

Fallon

NAS,

Fallon

NAS,

Fallon

Sheckler

Reservoir

Sheckler

Reservoir

Sheckler

Reservoir

Roads and hydrology from U.S. Geological Survey digital data,

1:100,000, 1979–80. Hypsography and water bodies from

U.S. Geological Survey digital data 1:250,000, 1971

Universal Transverse Mercator Projection, Zone 11

39o45'

119o00' 118o45' 118o30'

39o30'

39o15'

0

0

5

5

10 MILES

10 KILOMETERS

R. 27 E. R. 28 E. R. 29 E. R. 30 E. R. 31 E. R. 32 E.

T.

22

N.

T.

21

N.

T.

20

N.

T.

19

N.

T.

18

N.

T.

17

N.

T.

16

N.

EXPLANATION

Discharging playa—From Glancy and Katzer (1975, pl. 1)

Phreatophytes—From Glancy and Katzer (1975, pl. 1)

Irrigated land, 1984–90—From Bureau of Reclamation 

 digital data (Charles Johnson, Bureau of Reclamation, 

 written commun., 1993)

Wetlands

Hydrographic area boundary—From Rush (1968)

Topographic contour—Shows altitude of land surface. 

 Contour interval, 1,000 feet, with supplemental contour 

 at 4,200 feet. Datum is sea level

4000

Land where water rights have been purchased, 

 approximately located, as of June 4, 2003—Modified

 from U.S. Fish and Wildlife Service digital data

 (Jim Parden, U.S. Fish and Wildlife Service, 2003)

U.S. Geological Survey monitoring well and site 

 number—Appendix A

73

21

20

Monitoring well where water level has declined 

 1 foot or less from the early 1990's or late 1970's to 2003

Monitoring well where water level has declined more than 

 1 foot from the early 1990's or late 1970's to 2003

9

8

6,7

5

4

3

2 1

75

74

73

72

71

70

68,69 67

66

65 64

63

62 61

60

59 57

56

58

55 54 53

52

51

50

49 46,47

48

45

44

43

42

41

40

39 38 37

36

35

34

33

32

31

29,30

28

26,27

24,25

22,23 21

19,20

18

17 16

15

14

13

11 12

10

Figure 3. Approximate location of irrigated land, land where water-rights have been purchased, location of monitoring wells, 

and wells where water-level declines from the early 1990’s to 2003 are 1 foot or less and greater than 1 foot.
8 Evaluation of USGS Monitoring-Well Network and Potential Effects of Changes in Water Use, Newlands Project

Water-quality samples were collected from 7 of the network wells one to three times a year (app. A), usually once during the irrigation season and once during the non- irrigation season. Before sample collection, wells were purged of at least 

three casing volumes of water and in most cases, field measurements had stabilized in a flow-through chamber that measured 

temperature, pH, dissolved oxygen, and specific conductance. 

At some of the wells, production was not sufficient to maintain 

a constant flow through the flow-through chamber. At these 

wells, samples were collected after three casing volumes had 

been pumped. Filtered samples were collected after passing 

through a 0.45 micron in-line capsule filter. Samples were analyzed for major inorganic constituents and nutrients. Samples 

for nutrients were stored on ice or in a refrigerator until they 

were shipped to the USGS National Water-Quality Laboratory 

(NWQL) for analysis. The major inorganic constituents and 

nutrients were analyzed at the NWQL using methods described 

in Fishman and Friedman (1989) and Fishman (1993). 

Ground-water flow models of selected areas of Lahontan 

Valley developed by Herrera and others (2000) indicate that the 

amount of water level decline caused by reductions in irrigation 

is controlled largely by the distance from active irrigation 

canals. For this reason, monitoring wells in the network were 

characterized by distance from active irrigation canals or 

ditches, by the distance from currently and formerly irrigated 

land, and by acreage of nearby lands removed from irrigation.

The distance between each monitoring well and the nearest 

active canal or ditch, and irrigated field was measured using a 

survey-type distance-measuring wheel (table 1). For wells more 

than about 1,000 ft from canals or irrigated fields, distances 

were measured from 1:24,000 scale topographic maps or from 

scanned aerial photography. Twenty-five of the wells in the network are near land removed from irrigation and the distance 

from irrigated land has changed over time (fig. 3). For these 

wells, the distance from irrigated land in 2003 was used. 

In addition to distance, the direction of canals and irrigated 

fields from the well was determined in an upgradient, downgradient, or at a lateral direction relative to ground-water flow (fig. 

2; table 1). The direction is important because it is reasonable to 

assume that changes in water use upgradient from the wells will 

have a greater effect on water levels and water quality than 

changes in a lateral or downgradient direction. Changes in the 

use of irrigation canals over time near selected wells were determined from records of the TCID and discussions with TCID 

personnel (Dave Overvold, written and oral commun., 2003). 

Maps provided by USFWS were used to determine which 

wells in the network are near reductions in irrigation (Richard 

Grimes, USFWS, written commun., 2003; Jim Parden, 

USFWS, digital geospatial data, 2003). The maps show the 

approximate location of land where water rights have been purchased by the USFWS and the State of Nevada. In addition, 

water rights have been purchased on the western side of Lahontan Valley by the Pyramid Lake Paiute Tribe and the cities of 

Reno and Sparks, Nev. (Dave Overvold, Truckee-Carson Irrigation District, oral commun., 2004). 

The bulk of the land removed from irrigation is near the 

outer edges of irrigated areas near Stillwater and west and north 

of Carson Lake (fig. 3). Twenty-six of the wells in the network 

are within about 1 mi of lands where water-rights have been 

purchased (as of June 4, 2003). One of the 26 wells (well 1) was 

plugged in 2000, so only 25 of the original 75 wells in the network were used to evaluate changes caused by reductions in 

irrigation. From about 1995 to 2002, irrigation continued on a 

sporadic basis on some parcels of land where rights were purchased because of ongoing litigation over the water-rights purchases. On other parcels, irrigation continued using water rights 

transferred from elsewhere in Lahontan Valley (Richard 

Grimes, USFWS, oral commun., 2002). These practices 

required an analysis to determine the irrigation history of land 

near the 25 wells.

To determine the irrigation history of land near the 25 

wells, files showing the TCID serial numbers for parcels of land 

where water rights have been purchased were obtained from the 

USFWS (Richard Grimes, USFWS, written commun., 2003), 

Nevada State Lands (Ruth Danner, written commun., 2003), 

and TCID (David Overvold, oral commun., 2004). Acreages of 

individual fields in the parcels were determined from database 

files obtained from BOR, Fallon Field Office (Steven Munts, 

electronic commun., 2003). Parcel and field boundaries were 

transferred to 1:24,000 scale USGS topographic maps to allow 

measurement of the distance between wells and the nearest edge 

of irrigated and non-irrigated fields. 

The BOR database also provided information on the irrigation history of individual fields for 1992–95, 2001, and 2002. 

This information was not compiled or available for 1996–2000 

and 2003. The acreages of individual fields and the number of 

fields within each TCID parcel has changed somewhat over 

time (Steven Munts, BOR, Fallon Field Office, oral commun., 

2003). The field numbers and acreages used in this evaluation 

were those delineated in 2002 and acreages calculated for parcels removed from irrigation between 1992 and 2003 can only 

be considered approximate. 

To supplement the BOR database information for years 

when that data were not available (1996–2000 and 2003), aerial 

photographs in the form of 35-mm slides showing irrigated land 

near the 25 wells were digitally scanned. The slides were 

obtained from the BOR, Fallon Field Office for 1992–2001. 

The resulting images were printed at a scale of 1:24,000 to 

allow measurement of the distance between wells in the network and the nearest edge of irrigated and non-irrigated fields. 

Aerial photographs for the 2003 water year were not scanned, 

but were inspected at the BOR field office in Fallon, Nev. 

Appendix B summarizes the acreage of parcels removed 

from irrigation, the direction of the parcel from the well in terms 

of ground-water flow, and the average distance of each parcel 

from the nearest monitoring well. The parcels where waterrights have been purchased contain from 1 to as many as 43 

individual fields. The irrigation history of individual fields 

for 1992–2003 was summarized to obtain the irrigation history 

for the bulk of the fields comprising each parcel (app. B). 

The parcels summarized in appendix B are those closest to individual monitoring wells and considered most likely to affect 

water levels and water quality. Some parcels are listed in appendix B more than once if they may affect more than one well. 
Table 1. Distance and direction between monitoring wells and nearest canal, ditch, or reservoir and nearest irrigated field in 2003.

[Symbols: N, indicates none closer; * (asterisk), indicates site is near land removed from irrigation (table 2); shaded cells indicate wells less than 400 feet from 

nearest irrigated field and greater than 300 feet from nearest canal; directions are relative to ground-water flow; U, upgradient; L, lateral; D, downgradient.]

Well

number

(figure 3)

Distance

to nearest

canal,

ditch, or

reservoir

(feet)

Direction of

nearest canal,

ditch, or

reservoir

Distance to

nearest

upgradient

irrigated

field

(feet)

Distance to

nearest lateral

or

downgradient

irrigated field

(feet)

Well

number

(figure 3)

Distance

to nearest

canal,

ditch, or

reservoir

(feet)

Direction of

nearest canal,

ditch, or

reservoir

Distance to

nearest

upgradient

irrigated

field

(feet)

Distance to

nearest lateral

or

downgradient

irrigated field

(feet)

1 250 D 300 N *39 126 L 3 N

*2 1,000 U 1,500 N *40 1,000 U 2,000 N

3 5 U 30 N 41 3,100 L 5,000 N

4 100 D 3,500 N 42 3,600 L 3,000 N

5 34 L 5,800 N *43 145 U 300 150

6 40 D 1,500 N 735 U 300 100

7 40 D 1,500 N *45 150 U 5 N

8 25 U 11,000 2,000 *46 1,850 U 12,000 1,500

9 420 U 5 N *47 750 D 12,000 1,500

10 2,100 U 4,500 3,500 48 2,700 L 13,000 3,800

11 1,000 U 1,000 50 49 175 L 8,500 1,500

12 500 D 2,000 N 50 40 U 100 N

13 50 D 2,000 N 51 700 U 7,600 6,200

*14 165 D 200 N 52 17 L 75 N

15 5,200 L 2,500 200 53 230 D 100 N

*16 400 D 0 N 54 120 L 1,500 30

17 71 U 301 N 1,200 L 200 N

18 78 U 50 N 56 150 U 20 N

19 8,500 U 6,800 N 57 150 L 30 N

20 8,500 U 6,800 N 58 25 U 20 N

*21 3,800 U 3,500 N 59 700 U N 12,000

22 6,700 U 6,200 N *60 1,300 U N 4,200

23 6,700 U 6,200 N 61 3,100 U N 5,100

24 14,000 U 15,500 N *62 900 U 11,200 3,600

25 14,000 U 15,500 N *63 63 D 11,200 3,600

26 18,000 U 18,600 N *64 13 U 6,700 2,000

27 18,000 U 18,600 N *65 50 U 5 N

28 28,000 U 43,000 30,000 *66 20 D 2,600 25

29 38,000 U 48,000 N 67 300 D 0 N

30 38,000 U 48,000 N 68 150 U 7,000 N

*31 1,800 U 2,500 N 69 100 U 7,000 N

32 80 D 10 N *70 272 L 4,000 3,200

33 1,000 U 24,000 4,000 1,500 U 40 N

34 8,400 D N 7,000 72 200 L 11,000 N

35 3,800 D N 4,000 73 300 D N 300

*36 75 D 2,200 N 1,300 U 0 N

*37 900 D 5,200 1,200 75 14,700 D 18,000 N

*38 300 D 5,300 N

Methods Used 9

*44

55

*71

74
10 Evaluation of USGS Monitoring-Well Network and Potential Effects of Changes in Water Use, Newlands Project

The average distance of the parcel shown in appendix B 

was determined by multiplying the acreage of the individual 

fields by their minimum distance from the well. The resulting 

values were totaled, and divided by the total acreage of the parcel. The resulting average distance represents the approximate 

center point of the parcel. 

Water rights have been purchased from one to as many as 

15 parcels at varying distances and directions from the 25 network wells (app. B). To evaluate the effects of removing land 

from irrigation, the average distance between the well and 

the total acreage in all parcels removed from irrigation was 

determined. The average distance was determined for all 

parcels in the same direction from the well by multiplying 

the acreage of the parcel by its average distance from the well. 

The resulting values were totaled and divided by the total acreage removed from irrigation for all parcels in an upgradient, 

downgradient, or lateral direction from the well. The resulting 

average distances are shown in table 2, along with the year 

when irrigation was reduced on the bulk of the parcels, as 

determined from appendix B. 

The average distances for acreages listed in table 2 represent an approximate center point of the total acreage removed 

from irrigation for purposes of comparison and evaluation. In 

many cases, individual fields removed from irrigation are much 

closer to the monitoring wells than the calculated center points. 

For this reason, the minimum distance between the monitoring 

wells and the nearest field removed from irrigation also is listed 

in table 2. 

Evaluation of USGS Monitoring-Well 

Network

Using ground-water flow simulations of the study area, 

Herrera and others (2000, p. 51, 52, and 54–56) determined that 

when irrigation water applied to fields was reduced, simulated 

water-level declines were greatest in the areas most distant from 

active canals. In contrast, when the period of flow in a canal was 

shortened, or when flow was completely stopped, simulated 

water-level declines were greatest near the canal (Herrera and 

others, 2000, p. 51, 52, and 54–56). The distances involved in 

each case were not explicitly stated; however, the cells used in 

the simulations were 330 ft on each side. Simulated water-level 

declines caused by removing flow in a canal were generally 2 to 

4 ft in cells adjacent to the canal, but less than 1 ft a cell-width 

(330 ft) away from the canal (David E. Prudic, USGS, written 

commun., 2004). 

These simulation results indicate that wells within about 

300 ft of active irrigation canals may be relatively insensitive to 

changes in irrigation practices because seepage from the canals 

maintains stable water levels. Thus, the effects of reducing the 

amount of irrigation water applied to fields likely are greatest in 

wells distant from active canals. To detect the effects of changes 

in water use and provide information in terms of distance from 

such changes, the monitoring-well network should have wells 

distributed at varying distances from irrigation canals or 

ditches, irrigated land, and land removed from irrigation. 

Because the distances that may be critical in affecting ground 

water are uncertain, the distribution of wells at varying distances should be relatively continuous to provide information 

over a complete range of values. In addition, wells distant from 

changes in water use should be available to provide background 

information where changes are not taking place. 

Histograms were developed to graphically show the distribution of wells at varying distances from irrigation canals or 

ditches and from irrigated fields (figs. 4 and 5). Thirty-two of 

the wells are less than 300 ft from irrigation ditches, 12 of the 

wells are between 300 and 1,000 ft, and the remaining 31 wells 

are more than 1,000 ft from active irrigation ditches (fig. 4). The 

monitoring wells were often installed at the edges of fields to 

reduce damage to the well from farm equipment, causing a large 

number to be located relatively near irrigation ditches. It is 

unlikely that the 32 wells within 300 ft of canals will be useful 

in detecting changes caused by reductions in irrigation applications because seepage maintains relatively stable water levels 

near the canals. However, they will be useful to measure waterlevel changes from reductions in flow or discontinued use of 

individual canals. 

Figure 5 shows the distance from monitoring wells to 

fields where irrigation is currently (2003) continuing. Eighteen 

wells are less than 100 ft from irrigated fields, 10 wells are from 

100 to 400 ft, and there are no wells from 400 to less than 

1,200 ft. Sixteen wells are from 1,200 to less than 5,000 ft, 

and the remaining 31 wells are from 5,000 to 48,000 ft from 

irrigated land. 

The wells greater than 1,200 ft from an irrigated field may 

be too distant to detect the effects of reductions in irrigation. Of 

the 28 wells less than 1,200 ft from irrigated fields, 20 are also 

less than 300 ft from a canal (table 1). Because of their proximity to active canals, water-level declines caused by reduced irrigation near these 20 wells likely would be masked by seepage 

from the canals. Thus, only eight wells in the network (see 

shaded wells in table 1) likely will be useful in detecting the 

effects of future (after 2003) reductions in irrigation, should 

reductions take place near the eight wells.

From the analysis of historical irrigation, a total of about 

9,800 acres of land have been removed from irrigation (app. B). 

Twenty-five wells in the network are within about 1 mi of these 

lands (fig. 3; table 2). Near those 25 wells, parcels ranging from 

about 20 acres to almost 1,500 acres have been removed from 

irrigation, with the bulk being removed during the mid- to late1990's (table 2). The distances between the monitoring wells 

and the center points of parcels removed from irrigation ranged 

from 1,270 to 8,820 ft in an upgradient direction, and from 

about 1,140 to 6,800 ft in downgradient or lateral directions. 

The minimum distance between individual fields removed 

from irrigation and monitoring wells ranged from 0 ft (meaning 

that the field surrounded the well) to 200 ft or less at 7 wells 

(table 2). 

Of the 25 wells within 1 mi of land removed from irrigation, 13 are within 300 ft of canals (table 2). These 13 wells 

likely are not useful for detecting changes caused by reductions 

in irrigation because seepage from the canals maintains relatively stable water levels. Only the remaining 12 wells, which 

range from 400 to 3,800 ft from the nearest canal, may be useful 

for detecting continued changes from the current (2003) reductions in irrigation (see shaded wells, table 2). 
Evaluation of USGS Monitoring-Well Network 11

Table 2. Summary of acreage removed from irrigation near 25 monitoring wells.

[Symbols: --, indicates no acreage in that direction; shaded cells indicate wells more than 300 feet from canal; U, upgradient; D, downgradient; L, lateral]

Well

number

(figure 3)

Total

acreage

removed

from

irrigation

(appendix B)

Direction and average distance of acreage from 

well in terms of ground-water flow

Minimum

distance

to nearest

field

removed

from

irrigation

(feet)

Distance

to nearest

canal, 

ditch,

or reservoir

(table 1; 

feet)

Approximate

year of irrigation

removal and

gradient

direction 

(appendix B)

Upgradient

acres/

average

distance 

(feet)

Lateral

acres/

average

distance

(feet)

Downgradient

acres/

average

distance

(feet)

2 438 438/4,860 -- -- 1,200 1,000 1998- U

14 22 -- 22/1,200 -- 1,000 165 1997- L

16 95 95/3,510 -- -- 3,300 400 1996 - U

21 98 98/4,700 -- -- 4,200 3,800 Prior to 1987 - 

31 215 -- 215/1,690 -- 100 1,800 1995 -L

36 691 235/3,560 456/5,350 -- 600 75 2001 -U,L

37 1,000 187/5,560 552/4,890 261/6,800 1,900 900 1999-U, 2000-L, 

2000-D

38 1,000 187/5,560 552/4,890 261/6,800 1,900 1300 

1Distance is to Stillwater Point Reservoir.

1999-U, 2000-L, 

2000-D

39 621 269/3,220 318/2,540 34/2,560 200 126 1996-U, 1991-L, 

1995-D

40 970 970/6,190 -- -- 1,400 1,000 2001 - U

43 269 -- 269/5,390 -- 3,000 145 2003 -L

44 269 -- 269/5,390 -- 3,000 735 2003- L

45 842 545/5,480 160/2,370 137/4,040 1,500 150 1989-U, 2003-L, 

2000-D

46 545 -- -- 545/3,570 1,200 1,850 1989- D

47 545 -- -- 545/3,570 1,200 750 1989- D

50 230 230/2,200 -- -- 0 40 2003- U

60 255 -- 255/7,000 -- 4,400 1,300 2003- L

62 1,001 416/2,860 267/3,660 318/3,940 200 900 2001-U, 2003-L 

1994-D

63 1,001 416/2,860 270/3,660 318/3,940 200 63 2001-U, 2003-L 

1994-DL

64 1,336 746/3,020 115/3,190 475/5,180 200 13 1999&2001-U, 

1996-L, 

1992&1996-D

65 315 -- -- 315/4,040 2,700 50 2003 -D

66 310 310/1,270 -- -- 200 20 2003 - D

70 1,265 478/4,110 310/1140 477/2,450 20 272 1996-U, 1997-L 

1994-D

71 1,265 1,265/8,820 -- -- 5,500 1,500 1996 - U

72 285 285/5,390 -- -- 3,700 200 2001 - U
12 Evaluation of USGS Monitoring-Well Network and Potential Effects of Changes in Water Use, Newlands Project

0

500

1,0001,5002,000

2,5003,0003,500

4,0004,500

5,000

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

10,00015,00020,00025,00030,00035,00040,000

DISTANCE FROM NEAREST CANAL OR DITCH, IN FEET

NUMBER OF WELLS

0

500

1,0001,5002,0002,5003,000

3,5004,000

4,500

5,000

10,000

15,00020,00025,00030,00035,000

40,000

45,000

50,000

DISTANCE FROM NEAREST IRRIGATED FIELD, IN FEET

NUMBER OF WELLS

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

Figure 4. The distance of monitoring wells from active canals or ditches.

Figure 5. The distance of monitoring wells from irrigated land.
Evaluation of the Effects of Changes in Water Use 13

Evaluation of the Effects of Changes in 

Water Use

Changes in Ground-Water Levels

The most likely effect of reducing the amount of irrigation 

water applied to fields would be declines in ground-water levels 

because recharge from infiltration beneath irrigated fields 

would decrease. Declining water levels also may be caused by 

other factors such as long-term variations in precipitation, 

ground-water pumping, or the short-term seasonal decrease in 

recharge from infiltration beneath canals and irrigated fields at 

the end of each irrigation season. These factors may be superimposed on each other and complicate the evaluation of the 

effects of changes in water use. 

The timing and magnitude of seasonal water-level fluctuations have been previously studied by Glancy (1986) and Seiler 

and Allander (1993). Glancy (1986, p. 47) reported seasonal 

fluctuations of greater than 4 ft in areas west of Fallon and south 

of Soda Lake in water years 1977–78, decreasing to 1 to 2 ft 

northeast of Fallon and 1 to 3 ft south of Fallon. For wells near 

irrigated areas, water levels were highest in June or July when 

releases from Lahontan Reservoir were greatest, and lowest 

near the end of the non-irrigation season in February to March 

(Glancy, 1986, p. 43–45). Water year 1977 was considered a 

drought year with releases from Lahontan Reservoir totaling 

about 220,000 acre-ft (fig 6). Seiler and Allander (1993, p. 14) 

reported seasonal water-level fluctuations of 1 to 2 ft near irrigated areas in 1992, which was near the end of another longterm drought when releases from Lahontan Reservoir totaled 

only about 131,000 acre-ft (fig. 6). This suggests the magnitude 

of seasonal water-level fluctuations is related to the volume of 

surface water released from Lahontan Reservoir. Both studies 

noted greater seasonal fluctuations near irrigated areas than in 

areas distant from irrigation where seasonal water-level fluctuations are less than 1 ft.

Superimposed on seasonal fluctuations are more long-term 

changes in water levels caused by variations in annual precipitation in the headwaters of the Carson River. As shown by variations in the volume of water released from Lahontan Reservoir 

(fig. 6), dry conditions in 1977 were followed by a wet period 

in the early to mid-1980's, with a return to dry conditions from 

1986 to 1994. From 1977 to 1992, water levels in Lahontan Valley rose an average of about 2 ft in response to the wet period 

and declined from 1987 to 1992 an average of about 2.5 ft 

(Seiler and Allander, 1993, p. 14). The net change measured 

from 1977 to 1992 was a median decline of 0.58 ft (Seiler and 

Allander, 1993, p. 11). 

After 1992, releases from Lahontan Reservoir increased to 

above average from 1995 through 1998, followed by below 

average releases from 2000 to 2003 (fig. 6). From 1992 to 1998, 

water levels rose between 2 and 5 ft in most wells near irrigated 

areas, in response to increased releases from Lahontan Reservoir from 1995 to 1998 (app. C). In January 1997, flooding of 

the Carson River produced peak flows greater than any previously recorded (Thomas and Williams, 1997). In response to the 

four years of above average releases, water levels at many wells 

peaked during the middle of the irrigation season in 1997 or 

1998 (app. C). Smaller rises or no changes were measured in 

wells that were distant from irrigation (for example, wells 8, 26, 

59, 61, and 75; app. C).

The historical water-level measurements show that during 

periods of above average releases from Lahontan Reservoir, 

recharge from canal losses and infiltration of applied irrigation 

water creates an increase in ground-water storage that dissipates 

over time during subsequent periods of dry conditions. The latest period of dry conditions (2000–2003) corresponds to the 

time when water-level declines would be expected from reductions in irrigation on large parcels of land. Inspection of table 2 

shows that irrigation was removed from large parcels from the 

late 1990's to 2003. This makes it difficult to distinguish the 

effects of drought from the effects of removing land from irrigation, and it will remain difficult until above average releases 

from Lahontan Reservoir occur again sometime in the future. At 

that time, water levels near parcels removed from irrigation may 

continue to decline or show little or no rise compared to those 

where irrigation has continued. 

Because water levels at most wells near irrigated land have 

declined from 1998 to 2003, the effects of removing land from 

irrigation may be best shown by the difference between the 

greatest depth to water measured during 1992-95 and that measured during the same time of year during 2000–2003 (table 3). 

Negative values in table 3 indicate a water-level decline, and 

positive values indicate a water-level rise. Water-level differences from the mid 1970's, the earlier period of dry conditions, 

to 2000–2003 for selected wells, also are included in table 3 for 

comparison. Water-level declines to depths greater than in 

1992–95 ranged from 0.2 to 4.2 ft at 11 wells near land removed 

from irrigation (fig. 3, table 3). Water-level declines were 1 ft 

or less at 7 of the 11 wells but were 3.2, 2.1, and 4.2 ft at wells, 

62, 70, and 72, respectively, near the southern end of Lahontan 

Valley, and 1.2 ft at well 2 on the western side of the valley (fig. 

3). Water level declines from the mid-1970's to 2000–03 were 

3.9 and 4.1 ft at wells 70 and 72, respectively. Given the decline 

of less than 1 ft at the majority of the wells, it is uncertain if 

reductions in irrigation have significantly affected water levels 

in these wells. 

At 14 wells near land removed from irrigation, water levels 

have risen 0.4 to 6.5 ft compared to those in the early 1990's. 

Similarly, except for wells 7 and 20, water levels at 19 wells 

near continued irrigation did not change significantly, or have 

risen 0.2 to 5.1 ft (table 3). The water-level rises near continued 

irrigation may indicate that dry conditions in the early 1990's 

were more severe than those in 2003. Water deliveries for irrigation in 1992 and 1994 were less than the normally allotted 

volumes, while deliveries in 2003 were 100 percent of normal 

(David Overvold, Truckee-Carson Irrigation District, oral commun., 2004). 
Table 3. Changes in water levels at selected wells from the early 1990’s and mid-1970’s to 2003.

[Positive values indicate water-level rise, negative values indicate water-level decline]

Wells near land removed from irrigation Wells near continued irrigation

Site

number

(figure 3)

Water

level

date

Depth to

water

(feet)

Water-level

difference

(feet)

Site

number

(figure 3)

Water

level

date

Depth 

to

water

(feet)

Water-level

difference

(feet)

2 09/10/03

09/21/95

11.70

10.46 -1.2 3 03/17/0303/22/93

12.21

12.25 0.0

14 03/17/03

03/11/93

10.07

11.84 1.8 6 10/07/0310/24/92

12.59

14.00 1.4

16 12/12/02

11/27/92

4.76

7.17 2.4 7 05/16/0305/05/93

26.95

25.63 -1.3

21 09/08/03

09/29/93

20.58

19.79 -.8 7 04/03/0304/03/78

26.71

23.49 -3.2

31 10/07/03

09/29/93

10.00

9.60 -.4 9 04/02/0304/17/93

8.27

9.73 1.5

36 05/15/03

06/11/92

3.85

6.67 2.8 10 09/10/0309/07/93

16.42

16.45 0

37 09/10/03

09/27/93

6.43

8.57 2.1 10 09/10/0309/16/76

16.42

14.79 -1.6

38 12/13/02

11/04/92

6.96

12.00 5.0 11 01/27/0301/23/93

9.48

12.94 3.5

39 04/03/03

04/17/93

4.81

9.45 4.6 15 12/12/0211/27/92

7.24

9.95 2.7

40 09/24/01

03/19/93

9.24

10.78 1.5 17 03/17/0303/22/93

7.81

10.06 2.3

43 09/10/03

12/01/94

6.12

7.01 .9 18 04/03/0304/17/93

15.66

16.21 .6

44 12/13/02

11/28/92

5.81

7.77 2.0 20 09/08/0309/11/92

30.06

28.97 -1.1

45 10/07/03

10/10/92

3.45

9.98 6.5 20 09/08/0308/09/78

30.06

26.86 -3.2

46 03/17/03

02/22/92

9.63

9.28 -.4 32 03/17/0303/18/93

9.67

12.94 3.3

47 10/07/03

01/23/93

9.78

9.51 -.3 42 09/10/0309/15/92

3.46

3.67 .2

50 09/09/03

09/11/92

7.17

6.60 -.6 52 03/17/0303/18/93

7.05

9.19 2.1

60 09/09/03

08/03/94

12.26

12.04 -.2 53 03/17/0303/18/93

7.87

9.65 1.8

62 08/22/03

11/27/92

12.92

9.77 -3.2 54 09/10/0309/29/92

6.85

11.94 5.1

63 10/07/03

11/27/92

-1.30

-0.59 .7 56 10/07/0310/24/92

6.70

9.95 3.3

64 10/07/03

11/18/94

8.17

8.53 .4 57 12/12/0211/27/92

7.84

11.57 3.7

65 09/03/03

09/28/92

3.19

6.59 3.4 58 04/02/0304/17/93

8.44

10.33 1.9

66 10/15/03

10/24/92

5.82

7.18 1.4 67 03/17/0302/27/93

7.80

10.12 2.3

70 04/02/03

04/18/92

8.41

6.30 -2.1

70 04/02/03

04/09/76

8.41

4.49 -3.9

71 09/10/03

07/22/93

8.49

7.98 -.5

72 05/14/03

10/20/95

25.40

21.23 -4.2

72 05/14/03

05/19/76

25.4

21.29 -4.1

14 Evaluation of USGS Monitoring-Well Network and Potential Effects of Changes in Water Use, Newlands Project
Evaluation of the Effects of Changes in Water Use 15

Average flow

1967–2003 

YEAR

ANNUAL FLOW, IN ACRE-FEET

Carson River below Lahontan Reservoir

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

1970 1975 1980 1985 1990 1995 2000 2005

Water levels at wells 7, 10, and 20 near continued irrigation show long-term decline from the late 1970's (table 3, 

app. C). From the mid 1970's to 2000–2003, water levels 

declined 3.2 ft at well 7, 1.6 ft at well 10, and 3.2 ft at well 20; 

however, these wells are not near land removed from irrigation. 

The decline at well 7, screened about 140 ft below land surface, 

may have been caused by nearby industrial pumping from wells 

screened and gravel-packed from 100 to 190 ft below land 

surface and installed in 1997 and 2000 (K. Bernard, SMI Joist; 

K. Balnini, Wheeling Corrugating, oral communs., 2003). This 

is likely because water levels at nearby well 6, screened from 

23 to 28 ft, rose from 1992 to 2003 (table 3, app. A and C). 

Declines at wells 10 and 20 may have been caused by the 

discontinued use of nearby reservoirs, Sheckler and Old River, 

in about 1998 and 1990, respectively (fig. 3; David Overvold, 

Truckee-Carson Irrigation District, oral commun., 2003). Wells 

10 and 20 are about 1 mi from the reservoirs where use was 

discontinued. 

Simple linear regressions were developed to determine if a 

statistically-significant relation existed between water-level 

decline and the acreage removed from irrigation, or the distance 

from acreage removed. The dependent variables used in the 

regressions were water-level change for the 25 wells within a 

mile of land removed from irrigation, and water-level change 

for only the 11 wells that showed a water-level decline. The 

independent variables were the total acreage removed from irrigation in all directions; the acreage removed from irrigation 

upgradient of the well; the minimum and average distance from 

land removed from irrigation; and the total acreage in all directions and upgradient acreage removed, multiplied by both the 

minimum and average distance of the acreage. All regressions 

resulted in poor relations with coefficients of determination 

(R2) of 0.03 or less. 

It is likely that seepage from the extensive network of 

canals and ditches throughout Lahontan Valley effectively 

masks the effects of reductions in irrigation. To test this hypothesis, water-level change for all wells was regressed against 

canal distance, regardless of canal direction (fig. 7). This also 

results in a poor relation. However, figure 7 shows that most 

wells with declining water levels are more than 300 ft from the 

nearest canal. Canal distance may have a greater influence on 

the measured water-level changes than the acreage or distance 

of land removed from irrigation. In addition to these factors, the 

few number of wells (12) more than 300 ft from active canals, 

yet near reductions in irrigation does not allow development of 

meaningful relations between water-level decline and the acreage of, or distance from, land removed from irrigation.

Figure 6. Annual volume of water released from Lahontan Reservoir, 1967–2003.
16 Evaluation of USGS Monitoring-Well Network and Potential Effects of Changes in Water Use, Newlands Project

45 Data point and site number (figure 3) for individual well

95 percent confidence line

Regression line: y = -0.0009x + 1.5186, R2 = 0.1042

45

38 39

37

65

16

14

36

44

40

CANAL DISTANCE, IN FEET

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

WATER-LEVEL CHANGE, IN FEET

-5

-4

-3

-2

-1

0

1

2

3

4

5

6

7

8

Although no simple relation can be developed directly 

from the data, the general observation can be made that for 

wells near reductions in irrigation, water-level declines are 

greatest at wells distant from continued irrigation and active 

canals and near canals with decreased use. The three greatest 

water-level declines were measured at wells 62, 70, and 72 

(table 3). Wells 62 and 70 are surrounded by more than 1,000 

acres of land removed from irrigation, and water levels at well 

72 also may be affected by the upgradient removal of irrigation 

from 1,270 acres of land surrounding well 70 (fig. 3). Wells 62, 

70, and 72 are 3,600 ft or more from the nearest field that continues to be irrigated. Two wells, 70 and 72, are within 300 ft of 

a canal (table 1); however, surface-water deliveries in the canal 

decreased from about 1,500 acre-ft in 1998 to only about 50 

acre-ft in 2002 (David Overvold, Truckee-Carson Irrigation 

District, written commun., 2003). 

Figure 7 also shows that most wells with water-level rises 

of greater than about 2 ft are less than 300 ft from canals. Many 

of the wells with water-level rises are near Stillwater, Nev. 

(fig. 3). Although several wells near Stillwater (wells 36–40 

and 43–47) are near large areas removed from irrigation, water 

levels have risen in most wells and declined small amounts 

(<1 ft) at only two wells (46 and 47; table 3). Many of these 

wells are located near fields that continue to be irrigated, or are 

within 300 ft of the nearest canal. Flow and surface stage have 

increased in canals delivering water to wetland areas near 

Stillwater (David Overvold, Truckee-Carson Irrigation District, 

written and oral commun., 2003). Increased flow and surface 

stage likely has increased the seepage from the canals, causing 

water-level rises in the wells even though land near them was 

removed from irrigation. 

Changes in Ground-Water Quality

Herrera and others (2000) used a conceptual model of 

ground-water flow in the shallow aquifer to evaluate potential 

effects of changing irrigation practices in the Fallon area. They 

concluded that if water deliveries to lateral canals remain 

unchanged, irrigation reduction is likely to lower the average 

salinity of the shallow ground water. Removing canals from service will decrease seepage from canals, which likely will cause 

dissolved solids concentrations to increase in ground water for 

which canal seepage is a principal source of recharge. These 

conclusions were based on the fact that recharge from water 

applied to fields for irrigation adds more salt to the ground 

water than recharge from canal loss. This is because canal seepage is only slightly affected by evaporation whereas most water 

applied to fields is consumed by evapotranspiration, causing the 

dissolved-solids concentration to increase in the water that infiltrates to the water table. 

For these reasons, it is reasonable to assume that changes 

in water use in Lahontan Valley likely will cause changes in 

water quality in the shallow aquifer. However, the distinct 

change in the stable-isotopic composition of water at a depth of 

50 ft, discussed previously (see section titled "Physical and 

Hydrologic Setting"), shows that surface water applied during 

operation of the Newlands Project has not infiltrated to depths 

of more than 50 ft near the center of Lahontan Valley. Thus, the 

water chemistry of the intermediate aquifer has not been 

affected by the profound change in water use after widespread 

irrigation began in Lahontan Valley nearly 90 years ago. This 

indicates that it is unlikely that changes in irrigation practices 

will have an effect on water quality in the intermediate aquifer 

near the center of Lahontan Valley.

Figure 7. Relation between water-level 

change between 1992–95 and 2003 and distance from canals. Positive values indicate 

water-level rise, negative values indicate 

water-level decline. Numbers near points 

showing more than about 2 feet of waterlevel rise are site numbers, figure 3.
Suggestions for Improvement of the USGS Monitoring-Well Network 17

Five wells (14, 31, 39, 50, and 64; fig. 3) have been monitored since the late 1990's to evaluate long-term changes in 

water quality, and two wells (12 and 13) have been monitored 

since 2000 (app. A and D). The five wells were previously sampled after installation in the late 1980's. Plots of specific conductance were used to evaluate changes in water quality 

because it is related to the salinity of the water. Decreases in 

specific conductance will correspond with decreases in the salt 

content of the ground water (fig. 8). Laboratory values were 

generally used rather than field values because they were considered more accurate and, in some cases, field measurements 

from a flow-through chamber were not available. 

Well 14 shows strong seasonal changes in water level and 

water quality (app. C; fig. 8). It is unlikely that water quality has 

changed in the well as a result of changes in water use; only 22 

acres of land were removed from irrigation and they were more 

than 1,000 ft from the well (table 2). Well 14 is near a major 

canal delivering water to the southern part of the study area. The 

low specific conductance values occur during the irrigation season (app. D, fig. 8) and likely reflect seepage losses of relatively 

fresh water from the canal. The high conductance samples generally are associated with high nitrate concentrations (app. D). 

Since the well is near a house, the high nitrate could originate 

from septic system effluent that is diluted by canal seepage during summer months. 

Wells 31 and 50 show relatively small decreases in specific conductance that follow changes in water use. Water-quality data are not available for these wells for the period shortly 

before and after land was removed from irrigation. For this reason, it is uncertain whether the improvement in water quality is 

due to changes in irrigation or some other factor(s). 

Wells 39 and 64 show large changes in specific conductance (fig. 8) that may be related to changes in water use. In both 

of these wells, there was a large decline in the amount of 

sodium, chloride, and sulfate following removal of irrigation 

from nearby land (app. D). Because most water applied for irrigation is consumed by evapotranspiration, these changes are 

consistent with reduced irrigation. A large decline in specific 

conductance in well 39 occurred following removal of about 

260 acres of land, a minimum distance of 200 ft from the well 

in 1995 and 1996 (fig. 8; table 2). In addition, starting about 

2000, increased flows and surface stage in a nearby canal used 

for delivery of water to wetlands, probably resulted in greater 

seepage of low conductance water to the shallow aquifer. A 

decrease in specific conductance in well 64 was more than 

tenfold. It is uncertain, however, whether this can be associated 

with the removal of about 300 acres of land from irrigation near 

the well in 1992, and about 800 acres of land from 1994 to 1999, 

because few data are available near the time when the change 

occurred.

Wells 12 and 13 show only slight changes in specific conductance over the last three years. These wells are in a suburban 

area and were drilled to monitor changes in water quality attributable to urbanization. At present (2003), too little data are 

available to assess trends in water quality.

Changes in water quality are occurring in areas where 

changes would be expected on the basis of recorded changes in 

water use. Although the changes in ionic composition of the 

water are consistent with what would be expected, the available 

data are not sufficient to conclusively demonstrate that the 

changes resulted from reductions in application of irrigation 

water. Few data are available for periods near the time of 

changes in water use; therefore, it is difficult to evaluate 

whether changes in water use and changes in water quality are 

temporally associated. 

Suggestions for Improvement of the USGS 

Monitoring-Well Network

Wells where continued monitoring is considered useful are 

shown in figure 9. An evaluation of the monitoring-well network shows that 32 wells are less than 300 ft from an active 

canal or ditch, and thus likely can be useful for detecting waterlevel changes caused by reductions in flow or discontinued use 

of the canals. However, flow in most canals has not been significantly reduced over much of Lahontan Valley even after 

removal of about 9,800 acres of land from irrigation. 

Monitoring of all wells in irrigated areas, except those 

extremely close (< 50 ft) to canals, would provide useful background and comparison data on water-level changes caused by 

long-term changes in releases from Lahontan Reservoir. 

Twenty-five monitoring wells are within about 1 mi of a field 

removed from irrigation. Continued measurements on all 25 

wells near fields removed from irrigation may show if water 

levels eventually begin to decline. Twelve of those 25 wells also 

are more than 300 ft from a canal, and an additional 5 wells are 

near currently irrigated fields but are also more than 300 ft from 

a canal. Those 17 wells (shaded in tables 1 and 2) would provide 

the most useful data for determining the effects of removing 

fields from irrigation. Continued monitoring of wells near Carson Lake (wells 68 and 69) where water deliveries may increase 

and wells showing declines from discontinued use of reservoirs 

(wells 10 and 20) would be useful. 

The number of monitoring wells in areas distant from irrigated fields, such as wells 24–27 (fig. 9), could be reduced without sacrificing the ability of the network to detect water-level 

and water-quality changes caused by changes in water use. In 

all, monitoring of 23 wells could be discontinued. This would 

allow available funds to be spent on installing wells in more 

useful locations.

Additional wells located as near as possible, or even within 

currently irrigated fields where reductions in irrigation will 

likely occur, yet more than 300 ft from irrigation canals or 

ditches would provide an expanded data set to better evaluate 

the effect of water-use changes on water levels. Consultation 

with USFWS and other agencies purchasing water rights would 

allow locations for new wells to be selected and water-level 

measurements and water-quality sampling to begin before 

changes in water use are implemented. Data collection could 

begin while irrigation is still maintained with frequent, perhaps 

monthly, measurements of water levels and specific conductance following reductions in irrigation.
18 Evaluation of USGS Monitoring-Well Network and Potential Effects of Changes in Water Use, Newlands Project

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

15,000

20,000

10,000

500

600

700

800

900

1,500

2,000

3,000

4,000

5,000

1,000

1,500

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

1,000

10,000

1988 

1,500

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

15,000

20,000

1,000

10,000

150

200

300

400

500

600

700

800

900

100

1,000

150

200

300

400

500

600

700

800

900

100

1,000

150

200

300

400

500

600

700

800

900

100

1,000

1989 

1990 

1991 

1992 

1993 

1994 

1995 

1996 

1997 

1998 

1999 

2000 

2001 

2002 

2003 

1988 

1989 

1990 

1991 

1992 

1993 

1994 

1995 

1996 

1997 

1998 

1999 

2000 

2001 

2002 2003 

YEAR

YEAR

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER

Well 12

Well 14

Well 39

Well 64

Well 13

Well 31

Well 50

Changes in irrigation

Changes in irrigation

Change in irrigation

Change in irrigation

Change in irrigation

Figure 8. Changes in specific conductance at selected wells, 1988-2003.
Suggestions for Improvement of the USGS Monitoring-Well Network 19

4000

4000

4000

5000

4000

4200

5000

4000

4000

5000

5000

5000

4000

4000

4200

5000

4200

5000

CARSON SINK CARSON SINK CARSON SINK

STILLWATER

WILDLIFE

MANAGEMENT

AREA

STILLWATER

WILDLIFE

MANAGEMENT

AREA

STILLWATER

WILDLIFE

MANAGEMENT

AREA

STILLWATER STILLWATER STILLWATER

MARSH

Fallon

Stillwater Stillwater tillwater

RATTLESNAKE

HILL

RATTLESNAKE

HILL RATTLESNAKE

HILL

Stillwater

Point 

Reservoir

Stillwater

Point Reservoir

Stillwater

Point 

Reservoir

LAHONTAN MOUNTAINS LAHONTAN MOUNTAINS LAHONTAN MOUNTAINS

STILLWATER STILLWATER STILLWATER

RANGE

BUNEJUG MOUNTAINSBUNEJUG MOUNTAINS

BUNEJUG MOUNTAINS

HOT SPRINGS MOUNTAINSHOT SPRINGS MOUNTAINSHOT SPRINGS MOUNTAINS

LAHONTAN LAHONTAN LAHONTAN

VALLEY

SALT

WELLS

BASIN Salt Wells Salt Wells alt Wells

WHITE THRONE

MOUNTAINS

WHITE THRONE

MOUNTAINS

WHITE THRONE

MOUNTAINS

Carson

Lake

Carson

Lake

Carson

Lake

Soda

Lake

Soda Lake Soda

Lake Old River

Reservoir

Old River

Reservoir

Old River

Reservoir

Lyon

County

Lyon CountyLyon

County Churchill

County

Churchill

County

Churchill

County

Carson

Carson

River

River

UPSAL

HOGBACK

UPSAL

HOGBACK

UPSAL

HOGBACK

South

Branch

NAS,

Fallon

NAS, FallonNAS,

Fallon

Sheckler

Reservoir

Sheckler ReservoirSheckler

Reservoir

Roads and hydrology from U.S. Geological Survey digital data,

1:100,000, 1979–80. Hypsography and water bodies from

U.S. Geological Survey digital data 1:250,000, 1971

Universal Transverse Mercator Projection, Zone 11

39o45'

119o00' 118o45' 118o30'

39o30'

39o15'

0

0

5

5

10 MILES

10 KILOMETERS

R. 27 E. R. 28 E. R. 29 E. R. 30 E. R. 31 E. R. 32 E.

T.

22

N.

T.

21

N.

T.

20

N.

T.

19

N.

T.

18

N.

T.

17

N.

T.

16

N.

EXPLANATION

Discharging playa—From Glancy and Katzer (1975, pl. 1)

Phreatophytes—From Glancy and Katzer (1975, pl. 1)

Irrigated land, 1984–90—From Bureau of Reclamation 

 digital data (Charles Johnson, Bureau of Reclamation, 

 written commun., 1993)

Wetlands

Hydrographic area boundary—From Rush (1968)

Topographic contour—Shows altitude of land surface. 

 Contour interval, 1,000 feet, with supplemental contour 

 at 4,200 feet. Datum is sea level

4000

Land where water rights have been purchased, 

 approximately located, as of June 4, 2003—Modified

 from U.S. Fish and Wildlife Service digital data

 (Jim Parden, U.S. Fish and Wildlife Service, 2003)

41

20 Monitoring well and site number proposed 

 for continued measurement—Appendix A

Monitoring well and site number proposed 

 for discontinued measurement—Appendix A

9

8

6,7

5

4

3

2

75

74

73

72

71

70

68,69 67

66

65 64

63

62 61

60

59 57

56

58

54 53

52

51

50

49 46,47

48

45

44

43

42

41

40

39 38 37

36

35

34

33

32

31

29,30

28

26,27

24,25

22,23 21

19,20

18

17 16

15

14

13

11 12

10

Figure 9. Location of monitoring wells where continued monitoring would be useful, and where monitoring could be

discontinued.
20 Evaluation of USGS Monitoring-Well Network and Potential Effects of Changes in Water Use, Newlands Project

Summary and Conclusions

Because domestic wells tapping shallow ground water are 

an important source of potable water for rural residents of 

Lahontan Valley, the public has expressed concern over the 

acquisition of water rights for wetland areas in Carson Desert 

as directed by Public Law 101-618. Removal of land from irrigation and delivery of water to the wetland areas could cause 

shallow domestic wells to go dry and adversely affect shallow 

ground-water quality. In cooperation with Churchill County, 

periodic water-level measurements were made from 1992 to 

2003 at 75 wells and water-quality samples were collected from 

5 wells from 1998 to 2003 and 2 wells from 2000 to 2003. The 

purpose of the data collection was to obtain necessary data to 

evaluate the potential effects of changes in water use. In 2003, 

the USGS began an evaluation of the monitoring-well network. 

The purpose of the evaluation was to determine if the location 

and distribution of monitoring wells provide a reasonable 

means to measure the response of the shallow aquifer to 

changes in water use, and to determine if measurable changes in 

water levels and water quality have taken place.

Monitoring wells were characterized in terms of distance 

from active irrigation canals or ditches, and distance from currently (2003) or formerly irrigated land. Measurements on the 

ground and measurements from aerial photographs were used to 

determine the distance between the wells and canals and irrigated land. Maps, files, and aerial photographs from the U.S. 

Fish and Wildlife Service, the Bureau of Reclamation, and the 

Truckee-Carson Irrigation District were used to determine 

which network wells are near land where water-rights have 

been purchased as of June 2003, the irrigation history on those 

parcels from 1992 to 2003, and the flow of water in nearby 

canals. 

Of the 75 wells in the network, 32 wells are within 300 ft 

of canals and likely would not be useful to detect changes from 

reductions in irrigation applications because seepage from the 

canals maintains relatively stable water levels. These 32 wells 

would be useful to measure water-level changes from reductions in flow or discontinued use of individual canals. Twentyeight of the wells are within 400 ft of irrigated land. However, 

20 of these wells also are within 300 ft of a canal and likely not 

useful to detect future (after 2003) reductions in irrigation. 

Wells in the range of 400 to 1,200 ft from irrigated land are 

lacking, and wells greater than 1,200 ft from an irrigated field 

may be too distant to detect the effects of reductions in irrigation. Thus, the current network only has eight wells that are 

likely to be useful for detecting the effects of future (after 2003) 

reductions in irrigation. 

Purchases of water rights for use in wildlife areas has 

resulted in about 9,800 acres of fields being removed from irrigation, with the bulk being removed from the late 1990's to 

2003. Of the 75 wells in the network, 25 are within about 1 mi 

of a field removed from irrigation. Near the 25 wells, areas 

ranging from about 20 acres of land to almost 1,500 acres were 

removed from irrigation. Of the 25 wells, 13 are within 300 ft 

of canals and likely will not be useful for detecting changes in 

water levels caused by reductions in irrigation. The remaining 

12 wells range from about 400 to 3,800 ft from the nearest canal 

and may be useful for detecting changes in water levels caused 

by current (2003) changes in water use. 

The most likely effect of changes in water use caused by 

removing land from irrigation would be a decline in groundwater levels because recharge from infiltration beneath irrigated 

fields is decreased. Declining water levels also may have been 

caused by long-term variations in the amount of water released 

from Lahontan Reservoir. Historically, releases were generally 

below normal for 1976–78, 1987–94, and 2000–2003, and were 

above normal for 1982–86 and 1995–98. Water-level measurements from the mid-1970's to 2003 show that during wet conditions, characterized by above average releases from Lahontan 

Reservoir, recharge from increased infiltration causes an 

increase in ground-water storage that dissipates over time during the subsequent dry conditions. 

Because water levels at most wells near irrigated land have 

declined from 1998–2002, the effects of removing land from 

irrigation may be best shown by water-level declines between 

the last two periods of dry conditions and below normal releases 

from Lahontan Reservoir, 1992–95 and 2000–2003. At 11 of 

the 25 wells within about 1 mi of land removed from irrigation, 

water-levels declined from 0.2 to 4.2 ft between these periods. 

Water level declines were about 1 ft or less at eight of the wells 

but were 2 to 4 ft at three wells in the southern part of Lahontan 

Valley. Given the small amount of decline at most of the wells, 

it is uncertain if reductions in irrigation have affected water levels in these wells. 

In 15 of the 19 wells in areas where irrigation practices did 

not change, water levels rose between 0.2 and 5.1 ft between 

1992–95 and 2000–2003. This suggests that dry conditions in 

the early 1990's were more severe than those in 2003. At the 

remaining three wells, water levels declined 1.6 to 3.2 ft from 

the mid-1970's and 1990's to 2003. The decline at one well was 

likely caused by nearby industrial pumping, and the declines at 

the other two wells may have been caused by discontinued use 

of reservoirs about 1 mi from the wells.

Water-level declines from 1998 to 2003 because of below 

normal releases from Lahontan Reservoir coincide with the 

period of irrigation reductions, tending to mask declines 

directly caused by the reductions. It is likely that seepage from 

the diffuse network of canals and ditches in Lahontan Valley 

also masks declines caused by reductions in irrigation. In addition, the limited number of monitoring wells near land removed 

from irrigation, yet more than 300 feet from an active canal, 

does not allow a statistical correlation between reductions in 

irrigation and water-level declines. 

The maximum observed water declines were measured in 

three wells near or surrounded by more than 1,000 acres 

removed from irrigation, more than 3,600 ft from continued irrigation, and within 300 ft of a canal with greatly decreased use. 

Water-levels generally rose in monitoring wells near Stillwater, 
References Cited 21

Nev., even though large amounts of nearby land were removed 

from irrigation. This was likely caused by conditions in 2003 

that were not as dry as those in the early 1990's and additional 

seepage from the increased use and stage of canals for delivery 

of water to wetland areas.

Five wells have been monitored since the late 1990's and 

two wells have been monitored since 2000 to evaluate longterm changes in water quality. Plots of specific conductance 

were used to evaluate changes in water quality. Wells 39 and 64 

show large changes in specific conductance that may be related 

to changes in water use. The decline in specific conductance in 

well 39 followed removal of about 260 acres of land a minimum 

distance of 200 ft from the well in 1995 and 1996, and increased 

flows and surface stage in a nearby canal in 2000. A decrease in 

specific conductance in well 64 was more than tenfold. However, it is uncertain if the cause was related to changes in water 

use due to the lack of samples near the time when about 1,100 

acres were removed from irrigation near the well from 1992 to 

1999. Two wells, 31 and 50, show relatively small decreases in 

specific conductance that follow changes in water use. Whether 

the improvement in water quality is due to changes in irrigation 

or some other factor(s) is uncertain because water-quality data 

are not available near the time when land was removed from 

irrigation.

A distinct change in the stable-isotopic composition of 

water at a depth of 50 ft was noted near the center of Lahontan 

Valley in previous work. This suggests that water in the intermediate aquifer near the center of Lahontan Valley was 

recharged prior to construction of Lahontan Reservoir. This 

change indicates it is unlikely that recent changes in irrigation 

practices will have an effect on water quality in the intermediate 

aquifer near the center of Lahontan Valley.

The monitoring-well network could be improved by the 

addition of new wells located near lands where reductions in 

irrigation will likely occur, yet distant from irrigation canals or 

ditches. Water-level measurements and water-quality samples 

could be obtained prior to removal of irrigation, with measurements and sampling continuing after removal of irrigation. Continued monitoring of wells near land removed from irrigation on 

the current network during periods of greater releases from 

Lahontan Reservoir would show if water levels continue to 

decline and the magnitude of total decline.

References Cited

Axelrod, D.I., 1956, Mid-Pliocene floras from west-central 

Nevada: University of California, Publications in Geological 

Sciences, v. 33, 322 p.

Berris, S.N., Crompton, E.J., Joyner, J.D., and Ryan, Roslyn, 

2003, Water Resources Data Nevada, Water Year 2002: U.S. 

Geological Survey Water-Data Report NV-02-1, 600 p.

Bureau of Reclamation, 1987, Final environmental impact 

statement for the Newlands Project proposed operating 

criteria and procedures: Washington D.C., 332 p.

Bureau of Reclamation, 1988, Newlands Project Map 

No. 29–208–3: Sacramento, California, 1 sheet.

Davis, J.O., 1978, Quaternary tephrochronology of the Lake 

Lahontan area, Nevada and California: University of Nevada, 

Reno, Nevada Archeological Survey Research Paper 7, 

137 p.

Fishman, M.J., ed. 1993, Methods of analysis by the U.S. 

Geological Survey National Water Quality Laboratory— 

Determination of inorganic and organic constituents in water 

and fluvial sediments: U.S. Geological Survey Open-File 

Report 93–125.

Fishman, M.J., and Friedman, L.C., 1989, Methods for 

determination of inorganic substances in water and fluvial 

sediments: U.S. Geological Survey Techniques of WaterResources Investigations, book 5, chap. A1.

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

County, Nevada: U.S. Geological Survey Water-Supply 

Paper 2263, 62 p.

Glancy, P.A., and Katzer, T.L., 1975 [1976], Water-resources 

appraisal of the Carson River Basin, western Nevada: 

Nevada Division of Water Resources, Reconnaissance 

Report 59, 126 p.

Hem, J.D., 1989, Study and interpretation of the chemical 

characteristics of natural water: U.S. Geological Survey 

Water-Supply Paper 2254, 263 p.

Herrera, N.B., Seiler, R.S., and Prudic, D.E., 2000, Conceptual 

evaluation of ground-water flow and simulated effects of 

changing irrigation practices on the shallow aquifer in the 

Fallon and Stillwater areas, Churchill County, Nevada: U.S. 

Geological Survey Water-Resources Investigations Report 

99–4191, 70 p.

Hoffman, R.J., Hallock, R.J., Rowe, T.G., Lico, M.S., Burge, 

H.L., and Thompson, S.P., 1990, Reconnaissance investigation of water quality, bottom sediments, and biota associated 

with irrigation drainage in and near Stillwater Wildlife Management Area, Churchill County, Nevada, 1986-87: U.S. 

Geological Survey Water-Resources Investigations Report 

89–4105, 150 p.

Lico, M.S., 1992, Detailed study of irrigation drainage in and 

near wildlife management areas, west-central Nevada, 

1987–90. Part A—Water quality, sediment composition, and 

hydrochemical processes in Stillwater and Fernley Wildlife 

Management Areas: U.S. Geological Survey WaterResources Investigations Report 92–4024A, 65 p.

Lico, M.S., Welch, A.H., and Hughes, J.L., 1986, Hydrologic, 

lithologic, and chemical data for sediment in the shallow 

aquifer at two sites near Fallon, Churchill County, Nevada, 

1984–85: U.S. Geological Survey Open-File Report 86–250, 

43 p.

Lico, M.S., and Seiler, R.L, 1994, Ground-water quality and 

geochemistry, Carson Desert, Western Nevada: U.S. Geological Survey Open-File Report 94–31, 91 p.
22 Evaluation of USGS Monitoring-Well Network and Potential Effects of Changes in Water Use, Newlands Project

Maurer, D.K., Johnson, A.K., and Welch A.H., 1996, Hydrogeology and potential effects of changes in water use, Carson 

Desert agricultural area, Churchill County, Nevada: U.S. 

Geological Survey Water-Supply Paper 2436, 106 p.

Maurer, D.K., and Welch, A.H., 2001, Hydrogeology and 

geochemistry of the Fallon Basalt and adjacent aquifers, and 

potential sources of basalt recharge, in Churchill County, 

Nevada: U.S. Geological Survey Water-Resources Investigations Report 01–4130, 72 p.

Morrison, R.B., 1964, Lake Lahontan—Geology of southern 

Carson Desert, Nevada: U.S. Geological Survey Professional 

Paper 401, 156 p.

Morrison, R.B., 1991, Quaternary stratigraphic, hydrologic, and 

climatic history of the Great Basin, with emphasis on Lakes 

Lahontan, Bonneville, and Tecopa, in Morrison, R.B., ed., 

The Geology of North America, Quaternary Nonglacial 

Geology—Conterminous U.S. Geological Society of America, v. K–2, p. 283–320.

National Oceanic and Atmospheric Administration, 2002, 

Monthly station normals of temperature, precipitation, and 

heating and cooling degree days 1971–2000: Climatology of 

the United States No. 81, 26 Nevada, National Climatic Data 

Center, Asheville, North Carolina, 26 p.

Rowe, T.G., Lico, M.S., Hallock, R.J., Maest, A.S., and Hoffman, R.J., 1991, Physical, chemical, and biological data for 

detailed study of irrigation drainage in and near Stillwater, 

Fernley, and Humboldt National Wildlife Management 

Areas and Carson Lake, west-central Nevada, 1987–89: U.S. 

Geological Survey Open-File Report 91–185, 199 p.

Rush, F.E., 1968, Index of hydrographic areas in Nevada: 

Nevada Division of Water Resources, Information Report 6, 

38 p.

Seiler, R.L., and Allander, K.K., 1993, Water-level changes and 

directions of ground-water movement in the shallow aquifer, 

Fallon area, Churchill County, Nevada: U.S. Geological 

Survey Water-Resources Investigations Report 93–4118, 

74 p.

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in the Carson River Basin, California and Nevada: U.S. 

Geological Survey Fact Sheet FS–183–97, 2 p.

Welch, A.H., Lawrence, S.J., Lico, M.S., Thomas, J.M., and 

Schaefer, D.H., 1997, Ground-water quality assessment of 

the Carson River Basin, Nevada and California—results of 

investigations, 1987–91: U.S. Geological Survey WaterSupply Paper 2356–A, 93 p.

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Carson River basin, western Nevada and eastern California, 

1987–90: U.S. Geological Survey Open-File Report 94–39, 

139 p.

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and density: 2000 Nevada - Place, accessed July 7, 2004 at 

URL <http://factfinder.census.gov/servlet/GCTTable?_bm=

y&-geo_id=04000US32&-_box_head_nbr=GCT-PH1&-

ds_name=DEC_2000_SF1_U&-redoLog=false&-

mt_name=DEC_2000_SF1_U_GCTPH1_ST2&-format=

ST-7> .

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ds_name=DEC_2000_SF1_U&- redoLog=false&-format=

ST-2&-mt_name=DEC_2000_SF1_U_GCTPH1_ST7>.
APPENDIXES 23

APPENDIXES
Appendix A.--Monitoring well measurement frequency 1998–2003, site identifier, location, and well construction data. [Symbols: A, annual; Q, quarterly; M, monthly; I, intermittent; S, sampled; -- indicates not known. Datum for location NAD 27.] Site no. (figure 3) Site no. (Seiler and Allander, 1993)/measure- ment frequency Site identifier1 Local site identification2 Latitude (decimal degrees) Longitude (decimal degrees) Well depth (feet below land surface) Depth to top of open interval (feet below land surface) Dep

botto

op

inte

(fe

be

la

surf

1 45/Q 393108118590801101 N19 E27 08CCCB1 39.5188036 -118.9865486 69 -- -2 46/Q 393106118580301101 N19 E27 09CCCC1 39.5182778 -118.9685278 21 16 23 53/Q 392948118561101101 N19 E27 22DBAB1 39.4964167 -118.9374444 13

8 1

4 51/Q 393043118555101101 N19 E27 15ADDA1 39.5118600 -118.9318244 21 -- -5 47/Q 393120118545501101 N19 E27 11DCAC1 39.5199156 -118.9190464 24 -- -6 50/M 393023118544103101 N19 E27 13CCBB3 39.5063047 -118.9123794 28 23 27 48/M 393023118544101101 N19 E27 13CCB 1 39.5063047 -118.9123794 143 141 148 56/Q 393142118533201101 N19 E28 07BCBB1 39.5282489 -118.8932122 26 -- -9 60/M 392926118533001101 N19 E28 19CCCB1 39.4904717 -118.8926564 18 16 1

10 55/Q 392828118534901101 N19 E27 36DDCD1 39.4743608 -118.8979339 26 23 211 59/M 393038118512201101 N19 E28 17DAAC1 39.5104719 -118.8570997 14 11 112 none/M,S 393006118515101101 N19 E28 20ABDA1 39.5015831 -118.8651556 24 19 213 none/M,S 393004118514201101 N19 E28 20ABC 1 39.5010275 -118.8626556 29 19 214 63/M,S 392829118520001101 N19 E28 32BAAB1 39.4746389 -118.8676553 13 10 115 17/Q 392609118513401101 N18 E28 08DACB1 39.4357508 -118.8604319 29 16 216 65/Q 392817118495501101 N19 E28 34BCAA1 39.4701950 -118.8323761 13

8 1

17 16/Q 392735118484501101 N18 E28 02BABB1 39.4598889 -118.8134167 27 22 218 62/M 392925118482001101 N19 E28 23DCCA1 39.4903422 -118.8073506 30 -- -19 58/A 393155118483002101 N19 E28 11ABB 2 39.5318611 -118.8093206 35 31 320 57/A 393155118483001101 N19 E28 11ABB 1 39.5318611 -118.8093206 97 96 921 106/A 393309118515901101 N20 E28 32CAD 1 39.5524156 -118.8673781 128 -- -22 104/A 393335118512701101 N20 E28 32AAD 1 39.5596378 -118.8584889 32 -- -
23 105/A 393335118512702101 N20 E28 32AADA2 39.5596378 -118.8584889 22 20 224 99/A 393442118501802101 N20 E28 21DDDC2 39.5782489 -118.8393217 9 7 9 25 98/A 393442118501801101 N20 E28 21DDDC1 39.5782489 -118.8393217 67 66 626 101/A 393515118495602101 N20 E28 22BCA 2 39.5874156 -118.8332106 35 32 327 100/A 393515118495601101 N20 E28 22BCA 1 39.5874156 -118.8332106 87 84 828 none/A 393854118463801101 N21 E28 25ADD 1 39.6482486 -118.7782089 150 -- -29 125/A 394046118472603101 N21 E28 24BBA 3 39.6793589 -118.7915428 13 11 130 124/A 394046118472601101 N21 E28 24BBA 1 39.6793589 -118.7915428 109 106 1031 110/M,S 393458118431101101 N20 E29 22CBAC1 39.5849167 -118.7237619 12 9 132 66/Q 393252118415901101 N19 E29 02BABB1 39.5476953 -118.7007053 21 16 233 117/Q 393651118325701101 N20 E31 07BDCA1 39.6140842 -118.5501439 20 15 234 123/A 393341118241401101 N20 E32 33BBBD1 39.5613075 -118.4048608 -- -- -35 95/A 393153118275301101 N19 E31 11AACA1 39.5313081 -118.4656958 81 -- -36 122/Q 393311118304703101 N20 E31 33CACB3 39.5529742 -118.5140308 28 23 237 96/Q 393106118305301101 N19 E31 16BBDB1 39.5182528 -118.5156972 25 22 238 97/Q 393056118304901101 N19 E31 16BCAA1 39.5154750 -118.5145861 30 26 339 82/M,S 393052118333501101 N19 E30 13ACAA1 39.5141389 -118.5610000 12 10 140 112/A 393309118344701101 N20 E30 35DBDD1 39.5524183 -118.5807003 27 22 241 78/A 393248118374901101 N19 E30 04BBBC1 39.5465847 -118.6312578 15 4 142 79/A 393200118382601101 N19 E30 08BAAA1 39.5332514 -118.6415361 9 -- -43 81/Q 393110118361001101 N19 E30 10CDDD1 39.5193631 -118.6037567 8 -- -44 80/Q 393114118361001101 N19 E30 10CDDA1 39.5204742 -118.6037567 15 11 145 86/M 392938118344301101 N19 E30 23DBDD2 39.4938081 -118.5795886 11 -- -46 93/M 392828118361202101 N19 E30 34BAA 2 39.4743636 -118.6043117 13 -- -47 92/M 392828118361201101 N19 E30 34BAA 1 39.4743636 -118.6043117 25 -- -48 none/A 392758118365101101 N19 E30 33ADD 1 39.4660303 -118.6151453 11 -- -49 90/Q 392828118370702101 N19 E30 33ABAB2 39.4743633 -118.6195900 18 -- -50 71/M,S 393003118402001101 N19 E29 24ABDD1 39.5007517 -118.6732039 12 11 151 67/Q 393049118413501101 N19 E29 14ACB 2 39.5124181 -118.6945939 12 10 152 70/Q 392924118420901101 N19 E29 23CCDC1 39.4899183 -118.7034828 19 -- -53 77/Q 392759118411601101 N19 E29 35DAA 1 39.4663075 -118.6887594 10 8 154 75/Q 392825118435501101 N19 E29 33ABAC1 39.4735292 -118.7329281 28 24 255 74/Q 392816118453901101 N19 E29 32BCBB1 39.4710292 -118.7618181 21 -- -
Appendix A.--Monitoring well measurement frequency 1998–2003, site identifier, location, and well construction data—Continue

Site no. (figure 3) Site no. (Seiler and Allander, 1993)/measure- ment frequency Site identifier1 Local site identification2 Latitude (decimal degrees) Longitude (decimal degrees) Well depth (feet below land surface) Depth to top of open interval (feet below land surface) Dep

bott

o

inte

(f

be

la

sur

56 19/M 392642118470901101 N18 E28 12ABAC1 39.4449181 -118.7868186 15 12 57 28/Q 392540118454501101 N18 E29 18AADD1 39.4274722 -118.7635556 23 18 258 29/M 392439118443401101 N18 E29 21BCCB1 39.4107519 -118.7437608 30 -- 59 40/A 392554118373001101 N18 E30 09CDCC1 39.4315858 -118.6259786 111 -- 60 42/A 392407118392301101 N18 E30 30ABBA1 39.4018636 -118.6573681 24 19 261 43/A 392316118390001101 N18 E30 30DDDC1 39.3876972 -118.6509789 30 25 362 37/M 392309118414601101 N18 E29 35ABCB1 39.3857525 -118.6970917 32 25 363 38/M 392305118414601101 N18 E29 35ABCC1 39.3846414 -118.6970917 128 124 164 34/M,S 392327118425401101 N18 E29 27CDAD1 39.3907522 -118.7159817 13 11 65 35/I 392348118464401101 N18 E29 30BCBD1 39.3965853 -118.7798731 29 27 266 20/I 392359118492501101 N18 E28 34ACAA1 39.3838072 -118.8243186 10

7 

67 6/Q 392208118452701101 N17 E29 05BCAA1 39.3685556 -118.7585556 28 23 268 10/Q 392132118411004101 N17 E29 12BBBB4 39.3588083 -118.6870908 15 10 69 7/Q 392132118411001101 N17 E29 12BBBB1 39.3588083 -118.6870908 50 45 570 5/M 392008118465501101 N17 E28 13DAA 1 39.3354747 -118.7829275 17 15 71 11/A 391853118455801101 N17 E29 19DDCC1 39.3146417 -118.7670933 23 18 272 1/Q 391705118465402101 N16 E28 01AAAA2 39.2846419 -118.7826486 27 22 273 15/A 391857118383801101 N17 E30 20CDCC1 39.3157533 -118.6448661 24 19 274 2/A 391706118403801101 N16 E29 01ABBB1 39.2849200 -118.6782003 30 22 375 4/A 391532118371601101 N16 E30 09CDAA1 39.2588092 -118.6220867 27 -- 

1The site identifier is based on the grid system of latitude and longitude. The number consists of 15 digits. The first six denote the degrees, minutes, and seconds of latitude; t

note the degrees, minutes, and second of longitude; and the last two digits (assigned sequentially) identify the sites within a 1-second grid. For example, site 39264211847090 is 

and 188°47 ́09"W longitude, and is the first site recorded in that 1-second grid. The assigned number is retained as a permanent identifier even if a more precise latitude and lon

2The local site identification is used in Nevada to identify a site by hydrographic area (Rush, 1968) and by the official rectangular subdivision of the public lands referenced 

baseline and meridian. Each site designation consists of four units: The first unit is the hydrographic area number. The second unit is the township preceded by an N or S to ind

south of the baseline. The third unit is the range, preceded by an E to indicate location east of the meridian. The fourth unit consists of the section number and letters designatin

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

recorded. For example, site 101 N18 E28 12 ABAC1 is in the Carson Desert (Hydrographic Area 101). It is the first site recorded in the northeast quarter of the northwest quarter 

of the southeast quarter of section 12, Township 18 north, Range 28 east, Mount Diablo baseline and meridian.
Appendix B. Truckee-Carson Irrigation District (TCID) serial numbers of parcels near monitoring wells and summary of parcel size, averafrom well, gradient direction, irrigation history for water years 1992 through 2003, and irrigation prior to 1992 for parcels not irrigated 1992grouped and summarized by gradient direction. Irrigation history and acreages are approximate.[The average distance of parcels from USGS monitoring wells was determined by multiplying the acreage of individual fields by the minimum distance of the fie

the values, and dividing the total by the total acreage of the parcel. The resulting average distances represent the approximate center point of the parcels. Shaded c

tance of all parcels in a similar direction from well.Symbols: nd, indicates no data; U, indicates upgradient direction; L, indicates lateral direction; D, indicates downgradient direction; I, indicates irrigated; NI, indAcreage of zero indicates parcel still irrigated as of 2003. Average distance of zero indicates acreage surrounds well. Average distances for totals rounded to near

Averagedistance

 Site TCID Parcel of parcel Acres 

number serial size from well times Gradient 

(figure 3) number (acres)a (feet) distanceb direction 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 200

2 5351 48 7,600 363,280 U I I I I I I NI NI NI NI N

371 33 8,300 277,220 U I I I I I I NI NI NI NI N374 75 5,600 417,760 U I I I I I I NI NI NI NI N376 69 3,300 226,050 U I I I I I I NI NI NI NI N

5350 70 6,000 418,800 U I I I I I I NI NI NI NI N

378 31 4,300 133,730 U I I I I I I NI NI NI NI N409 68 3,200 216,000 U I I I I I I NI NI NI NI N407 31 1,800 55,080 U I I I I I I NI NI NI NI N411 14 1,300 18,720 U I I I I I I NI NI NI NI N

Total upgradient 438 4,860 2,126,640 c

14 567-2 22 1,200 L I I I I I NI NI NI NI NI N16 592-4 & 7 24 2,990 70,564 U NI NI NI NI NI NI NI NI NI NI N

554 45 2,550 115,005 U I I I I NI NI NI NI NI NI N

565-44 26 5,650 145,770 U NI I NI NI NI NI NI NI NI NI N

Total upgradient 95 3,510 331,339 c

21 854-2&3 35 5,900 205,320 U NI NI NI NI NI NI NI NI NI NI N

455-3to-6 63 4,040 254,520 U NI NI NI NI NI NI NI NI NI NI N

Total upgradient 98 4,700 459,840 c

31 865 w 119 350 41,475 L I NI I NI NI NI NI NI NI NI N

865 e 96 3,330 320,679 L NI NI NI NI NI NI NI NI NI NI N

Total lateral 215 1,690 362,154 c
Appendix B.—Continued.

Average distance Site TCID Parcel of parcel Acres 

number serial size from well times Gradient 

(figure 3) number (acres)a (feet) distanceb direction 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 200

36 819-2 208 3,960 825,264 U I I I I I I I NI I NI NI 

2169 27 500 13,500 U NI I I NI I I I NI NI NI NI 

Total upgradient 235 3,560 838,764 c 819-1-B 456 5,350 2,436,925 L I I I I I I I I I NI NI 

Site total 691 37 & 38 825 157 5,110 804,314 U I I I I I I I NI NI NI NI 

827 29 8,000 234,400 U NI I I I I I I NI NI NI NI 

Total upgradient 187 5,560 1,038,714 c 2169-B 12 6,200 76,880 L NI I I NI NI NI NI NI NI NI NI 

821 540 4,860 2,621,970 L I I I I I I I I NI NI NI 

Total lateral 552 4,890 2,698,850 c 821-8 148 8,230 1,213,925 D I NI NI I I NI NI NI NI NI NI 

2169-A 33 2,820 93,342 D NI I I I NI NI I I I NI NI 

821-6 80 5,810 466,543 D I I I I I NI NI I NI NI I 

Total downgradient 261 6,800 1,773,810 c Site total 1,000 39 821-5 154 4,260 653,910 U NI I NI I NI NI NI NI NI NI NI 

828 42 1,370 57,814 U I I NI I I I I I I I I 770 73 2,120 155,396 U NI I I I NI NI NI NI NI NI NI 

Total upgradient 269 3,220 867,120 c 830 318 2,540 L NI NI NI NI NI NI NI NI NI NI NI 

773-2 34 2,560 D I I I NI NI NI NI NI NI NI NI 

 Site total 621 40 746 146 5,790 847,077 U I I NI NI NI NI NI NI NI NI NI 

747 73 5,980 438,334 U NI NI NI NI NI NI NI I NI NI NI 758 73 7,000 508,200 U NI I I NI NI NI NI NI NI NI NI 744 207 6,170 1,274,722 U I I I I NI I I I I NI NI 750 107 4,680 501,696 U I I I I I NI NI NI NI NI NI 752 7 1,400 9,800 U I I I I I I I I NI I I 

752-1 144 3,470 499,333 U I I I NI NI NI NI NI NI NI NI 

759 69 7,680 532,224 U I I I I I I I I I I I 
Appendix B.—Continued.

Averagedistance

 Site TCID Parcel of parcel Acres 

number serial size from well times Gradient 

(figure 3) number (acres)a (feet) distanceb direction 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 200

755 72 9,650 695,765 U I I I I I I I I I I I 756 71 9,730 692,776 U I I I I I I I I I I I 

Total upgradient 970 6,190 5,999,927 c

43 & 44 778 51 6,000 306,000 L I I I I I I I I I I I 

775 11 3,000 33,900 L NI NI NI NI NI NI I I I NI I 

775-1 63 4,000 252,400 L NI I NI I NI NI NI NI NI NI NI 

755 72 5,000 360,500 L I I I I I I I I I I I 756 71 7,000 498,400 L I I I I I I I I I I I 

Total lateral 269 5,390 1,451,200 c

45 804 348 4,780 1,664,396 U NI NI NI NI NI NI NI NI NI NI NI 

805 63 6,230 389,998 U NI NI NI NI NI NI NI NI NI NI NI 806 93 6,110 567,619 U I I I NI NI NI NI NI NI NI NI 

900-A 21 9,500 196,650 U I I I I I I NI NI NI NI I 900-B 20 8,290 166,629 U NI I I I I I NI NI NI NI I 

808 0 7,670 0 U I I I I I I I I I I I 

Total upgradient 545 5,480 2,985,292 c

793 107 2,180 232,388 L I I NI NI NI NI NI I NI NI I 

794-1 54 2,740 146,864 L I I I I NI I I I I NI I 

Total lateral 160 2,370 379,252

795 71 2,500 178,250 D I I NI NI NI NI NI I NI NI NI 778 51 5,360 273,360 D I I I I I I I I I I I 

778A,B 15 6,900 103,500 D NI NI NI NI NI NI NI NI NI NI NI 

Total downgradient 137 4,040 555,110 c

Site total 842

46 & 47 804 348 3,650 1,270,930 D NI NI NI NI NI NI NI NI NI NI NI 

805 63 1,200 75,120 D NI NI NI NI NI NI NI NI NI NI NI 806 93 4,430 411,547 D I I I NI I NI NI NI NI NI NI 

900-A 21 4,380 90,666 D I I I II I I NI NI NI NI I 900-B 20 4,850 97,485 D NI I I I I I NI NI NI NI I 

808 0 3,380 0 D I I I I I I I I I I I 

Total downgradient 545 3,570 1,945,748 c
Appendix B.—Continued. Average distance Site TCID Parcel of parcel Acres 

number serial size from well times Gradient 

(figure 3) number (acres) a (feet) distanceb direction 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 200

50 674 91 2,250 205,425 U I I I I NI NI NI NI NI NI I 

670 84 1,420 118,854 U NI I I I NI NI NI NI NI NI N

783-1 0 1,600 0 U I I I I NI I I I I I I 

668 23 8,000 180,800 U I NI I NI NI NI I I I I I 

673-1 32 0 0 U I NI NI NI NI NI NI NI NI NI N

Total upgradient 230 2,200 505,079 c 60 4A12 119 7,000 834,400 L I I I I I NI I I I NI N

4A05 135 7,000 947,100 L I I I I I I I I I I I 

Total lateral 255 7,000 1,781,500 c 62 & 63 4A10 260 1,580 410,010 U I I I I I I NI I NI NI N

303-1 38 3,500 131,600 U NI I NI NI NI NI NI NI NI NI N

4A12 119 5,450 649,640 U I I I I I NI I I I NI N

Total upgradient 416 2,860 1,191,250 c 318-1&2 66 390 25,623 L I I I I NI I NI I I NI I 

4A05 135 5,850 791,505 L I I I I I I I I I I I 

302 66 2,430 159,651 L NI I NI NI NI NI NI NI NI NI N

Total lateral 267 3,660 976,779 c 317 98 1,020 99,960 D NI I NI NI NI NI NI NI NI NI N

328 74 3,400 252,960 D I NI NI NI NI NI NI NI NI NI N326 146 6,180 902,280 D NI NI NI NI NI NI NI NI NI NI N

Total downgradient 318 3,940 1,255,200 c Site total 1,001 64 305-1 223 7,130 1,590,703 U I I I I NI I I I I NI N

303-1 38 3,000 112,800 U NI I NI NI NI NI NI NI NI NI N

304 308 1,200 369,240 U NI I NI I I I I NI NI NI N

24 178 1,020 181,254 U NI I NI NI NI NI NI NI NI NI N

Total upgradient 746 3,020 2,253,997 c

24-1 115 3,190 365,893 L NI I I I NI NI NI NI NI NI N

307 0 4,500 0 L I I I I I I NI I I I I 

Total lateral 115 3,190 365,893 c
Appendix B.—Continued.

Averagedistance

 Site TCID Parcel of parcel Acres 

number serial size from well times Gradient 

(figure 3) number (acres) a (feet) distanceb direction 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 200

25-1 170 1,600 271,200 D I I I I NI NI NI NI NI NI NI 

316 0 5,300 0 D NI I I I NI NI NI NI NI NI I 

24-3-4 157 9,000 1,409,400 D NI NI NI NI NI NI NI NI NI NI NI 24-3-1 100 5,000 500,000 D NI NI NI NI NI NI NI NI NI NI NI 24-3-3 49 5,710 280,932 D NI NI NI NI NI NI NI NI NI NI NI 

Total downgradient 475 5,180 2,461,532 c

Site total 1,336

65 311 181 2,870 520,044 D I I I I I I I I I I I 

310 134 5,620 751,956 D I I I I I I I I I I I 

Total downgradient 315 4,040 1,272,000 c

66 170 139 1,310 182,090 U I I I I I I I I I I NI 

2143 112 1,100 122,760 U I I I I I I I I I I I 

171 59 1,480 87,172 U I I I I I I I I I I I 

Total upgradient 310 1,270 392,022 c

 70 6-A-1 81 4,270 346,724 U I I I I NI NI NI I NI I NI 

6-A-2 32 4,300 139,320 U I I I I NI NI NI I I NI NI 6-A-3 33 3,140 102,992 U I I I NI NI NI NI I NI NI NI 6-A-4 95 3,320 314,072 U I I I I NI NI NI I NI NI NI 

13-1 34 2,220 74,370 U I I NI NI NI NI I I NI NI 

6-12- 44 9,400 412,660 U I I I NI NI I I I NI I 6-10- 81 4,740 385,362 U I I I I I I I I I I I 

18-1&-1-A 78 2,400 186,960 U I I I NI NI NI NI NI NI NI NI 

Total upgradient 478 4,110 1,962,460 c

13-2 33 2,910 95,739 L I I I I NI NI NI I NI NI NI 

45 109 1,450 158,485 L I NI I NI NI NI NI NI NI NI NI 

45-1 32 1,020 32,538 L I NI I NI I NI NI NI NI NI NI 

15 136 480 65,280 L I I I I I NI NI NI NI NI NI 

 Total lateral 310 1,140 352,042 c

13-3 37 1,660 60,922 D I I I I NI NI NI I I NI NI 

46 72 1,100 79,640 D NI NI I NI I I I I I NI NI 20 368 2,790 1,025,883 D NI I NI NI NI NI NI NI NI NI NI 

Total downgradient 477 2,450 1,166,445 c

Site total 1,265
Appendix B.—Continued. Average distance Site TCID Parcel of parcel Acres 

number serial size from well times Gradient 

(figure 3) number (acres) a (feet) distanceb direction 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 200

71 6-A-1 81 12,000 974,400 U I I I I NI NI NI I NI I NI 

6-A-2 32 12,600 408,240 U I I I I NI NI NI I I NI NI 6-A-3 33 11,500 377,200 U I I I NI NI NI NI I NI NI NI 6-A-4 95 10,800 1,021,680 U I I I I NI NI NI I NI NI NI 

13-1 34 10,000 335,000 U I I NI NI NI NI I I NI NI 13-2 33 10,500 345,450 U I I I I NI NI NI I NI NI NI 13-3 37 7,700 282,590 U I I I I NI NI NI I I NI NI 

20 368 6,500 2,390,050 U NI I NI NI NI NI NI NI NI NI NI 

6-12- 44 17,700 777,030 U I I I NI NI I I I NI I 6-10- 81 11,000 894,300 U I I I I I I I I I I I 

46 72 5,500 398,200 U NI NI I NI I I I I I NI NI 

18-1&-1-A 78 9,600 747,840 U I I I NI NI NI NI NI NI NI NI 

45 109 6,800 743,240 U I NI I NI NI NI NI NI NI NI NI 

45-1 32 8,400 267,960 U I NI I NI I NI NI NI NI NI NI 

15 136 8,700 1,183,200 U I I I I I NI NI NI NI NI NI 

Total upgradient 1,265 8,820 11,146,380 c 72 23 158 6,200 978,360 U I I I I I nd NI nd I NI NI 

2149 106 3,700 391,090 U I I I NI NI nd NI nd NI NI NI 2184 22 7,780 168,048 U NI NI NI NI NI nd NI nd NI NI NI 

Total upgradient 285 5,390 1,537,498 c Project total 9,770 aRounded to nearest acre. bNumber calculated using non-rounded value for parcel size. cValue is sum for parcels in same direction
APPENDIX C 33

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Appendix C. Water-level hydrographs for monitoring wells for period of record at each well.
34 Evaluation of USGS Monitoring-Well Network and Potential Effects of Changes in Water Use, Newlands Project

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Appendix C. Changes in water levels at selected wells from the early 1990’s and mid-1970’s to 2003--Continued.
APPENDIX C 35

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Appendix C. Changes in water levels at selected wells from the early 1990’s and mid-1970’s to 2003--Continued.
36 Evaluation of USGS Monitoring-Well Network and Potential Effects of Changes in Water Use, Newlands Project

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Appendix C. Changes in water levels at selected wells from the early 1990’s and mid-1970’s to 2003--Continued.
APPENDIX C 37

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Appendix C. Changes in water levels at selected wells from the early 1990’s and mid-1970’s to 2003--Continued.
38 Evaluation of USGS Monitoring-Well Network and Potential Effects of Changes in Water Use, Newlands Project

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WATER LEVEL, IN FEET BELOW LAND SURFACE

YEAR

19741976197819801982198419861988199019921994199619982000200220041974197619781980198219841986198819901992199419961998200020022004

Appendix C. Changes in water levels at selected wells from the early 1990’s and mid-1970’s to 2003--Continued.
APPENDIX C 39

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

Well 53

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

Well 51

Well 55

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

Well 52

Well 50

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

Well 49

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

Well 54

Well 56

WATER LEVEL, IN FEET BELOW LAND SURFACE

YEAR

19741976197819801982198419861988199019921994199619982000200220041974197619781980198219841986198819901992199419961998200020022004

Appendix C. Changes in water levels at selected wells from the early 1990’s and mid-1970’s to 2003--Continued.
40 Evaluation of USGS Monitoring-Well Network and Potential Effects of Changes in Water Use, Newlands Project

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

Well 61

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

-5

-4

-3

-2

-1

0

1

2

3

4

5

6

7

8

9

10

Well 59

Well 63

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

Well 60

Well 58

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

Well 57

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

Well 62

Well 64

WATER LEVEL, IN FEET BELOW LAND SURFACE

YEAR

19741976197819801982198419861988199019921994199619982000200220041974197619781980198219841986198819901992199419961998200020022004

Appendix C. Changes in water levels at selected wells from the early 1990’s and mid-1970’s to 2003--Continued.
APPENDIX C 41

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

Well 69

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

Well 67

Well 71

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

Well 68

Well 66

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

Well 65

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

Well 70

Well 72

WATER LEVEL, IN FEET BELOW LAND SURFACE

YEAR

19741976197819801982198419861988199019921994199619982000200220041974197619781980198219841986198819901992199419961998200020022004

Appendix C. Changes in water levels at selected wells from the early 1990’s and mid-1970’s to 2003--Continued.
42 Evaluation of USGS Monitoring-Well Network and Potential Effects of Changes in Water Use, Newlands Project

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

Well 75

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

Well 74

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

Well 73

YEAR

WATER LEVEL, IN FEET BELOW LAND SURFACE

YEAR

1974197619781980198219841986198819901992199419961998200020022004

1974197619781980198219841986198819901992199419961998200020022004

Appendix C. Changes in water levels at selected wells from the early 1990’s and mid-1970’s to 2003--Continued.
Appendix D. Summary of water-quality analyses for samples taken from monitoring wells—Continued

Site

number

(figure 3)

Date Time

Temperature

(°C)

Specific

conductance pH

Ammonia

as N

(mg/L)

Ammonia +

organic

nitrogen

as N

(mg/L)

Nitrite +

nitrate(mg/L)

Nitrite

as N

(mg/L)

Total

phosphorus

(filtered,

mg/L)

Field 

(μS/cm)

Laboratory

(μS/cm)

Field Labora- tory

12 09/14/2000

02/27/200111/20/200106/20/200201/29/200309/16/2003

120011401000100011001030

20.016.1

--

18

164

22.4

413388

--

411470460

408400417417420426

9.199.48.99.48.9

9.19.199.198.9

<0.02

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

<0.10

E.07

.11

<.1

E.05

<.1

0.22

.21.27.24.2.15

<0.01

<.006<.008<.008<.008<.008

1.351.21

.93

1

.94.91

13 09/14/2000

02/28/200111/20/200106/20/200201/29/200309/15/2003

103210401200120013301330

20.516.516.51817.519.5

288313

--

348348360

295337317338313324

88.38.58.37.88.3

8.28.38.48.17.88.2

<.02<.04<.04<.04<.04<.04

<.1

E.06

<.1

E.06

<.1

.21

.81.85.77.73.97.43

.015

<.006<.008<.008

E.006

<.008

.34.35.28.27.21.81

14 06/21/1988

06/21/198812/09/199809/21/199902/02/200008/07/200002/28/200103/20/200206/17/200201/28/200306/11/200309/16/2003

14001400R1200101513451010122509301030100013001230

18181519142013

--

15.513.7

--

21

346346225240517275364

--

265520

--

320

353352229238554281393603275481

--

278

6.96.97.16.8776.9

--

7.37.36.76.8

7.57.77.47.377.37.17.47.46.9

----

<.01<.01<.02<.02<.02<.02<.04<.04<.04<.04<.04<.04

<.2

.3

<.1

E.09

.36

E.06

.1.23

E.05

.11

E.05

<.1

.49.49.21.2

14.1

.27

14.67

.17

1.71

.13.1

<.01<.01<.01<.01<.01<.01<.006<.008<.008<.008<.008<.008

----

.15.17.12.16.12.12.13.12

--

.16

31 08/02/1988

12/17/199809/22/199902/01/200008/09/200003/14/200106/24/200202/03/200309/19/2003

160013301330130011201100103012151130

--

152214.51914

----

15

--

14,80014,00013,00014,80013,90010,900

----

15,80015,10014,00014,20014,60014,20012,70012,70011,600

7.57.37.47.57.47.47.67.37.6

6.47.37.47.47.57.57.57.77.7

.69.29.21.13.25.16.30.19

<.04

2.502.21.1

.49

1.71.5

E1.7

1.31

<.10

.05

<.05<.05<.05<.05

E.03

<.06<.06

.01

<.01<.01<.01<.01<.006<.008<.008<.008

--

.38.21.19.36.35.32.34.34

Appendix D. Summary of water-quality analyses for samples taken from monitoring wells.

[Symbols: E, estimate; <, less than; --, not analyzed; R, sequential replicate of previous analysis.]
39 08/02/1988 05/03/1989 08/22/1994 12/15/1998 09/23/1999 01/31/2000 08/08/2000 03/1/2001 03/21/2002 06/18/2002 01/28/2003 09/17/2003 1200 1315 1300 1315 1130 1230 1015 1315 1045 1045 1300 1300 16.5 15171416.5 12.5 17.5 12.5 1317.5 1319 5,030 5,910 6,040 1,430 1,680 1,640 1,850 1,550 2,350 2,100 1,360 1,710 4,880 5,690 6,110 1,570 1,660 1,770 1,920 1,690 2,290 2,270 1,650 1,510 6.7 76.9 776.9 6.9 77.2 7.4 7.4 6.9 7.4 7.2 7.1 7.1 7.1 7.2 7.1 7.1 7.4 7.4 7.7 7.3 .16 --.17 .11 .47 .22 .34 .19 .13 .13 .12 .2 1--1.4.96 1.2 1.5 1.5.9.93 .95 .68 .88 <.1 --<.05 <.05 <.05 <.05 <.05 <.05 <.05 <.05 <.06 <.06 <.01 --<.01 <.01 <.01 <.01 <.01 <.006 <.008 <.008 <.008 <.008 ----.39 .6.73 .43 .92 .66 .64 .86 .6.74 50 08/03/1988 09/01/1988 12/11/1998 09/22/1999 02/01/2000 08/08/2000 03/02/2001 03/21/2002 06/18/2002 02/03/2003 09/17/2003 1000 1530 1140 1130 1110 1220 1030 1300 1230 1030 1430 15.5 1712.5 14.5 12179.5 -- 15.2 12.7 16.3 1,440 1,740 1,490 1,610 1,690 1,400 1,340 1,030 1,100 1,000 1,450 1,690-- 1,560 1,620 1,610 1,410 1,420 1,150 1,160 1,320 1,260 8.1 87.7 7.6 7.9 7.7 7.7 7.9 7.7 7.5 7.5 8.3 --7.8 7.8 7.8 7.9 7.8 8.1 7.9 7.8 7.8 .02 --.02 <.02 <.02 <.02 <.04 <.04 <.04 <.04 <.04 .60 --.55 .5.49 .51 .4.38 .37 .42 .36 1.30 --.95 .4.33 .34 .18 .31 .20 .15 .13 .03 --.031 .016 .022 .013 .012 .017 .012 .012 E.006 ----.17 .19 .19 .21 .22 .19 .17 .16 .16 64 07/13/1988 12/10/1998 09/21/1999 02/04/2000 08/07/2000 03/01/2001 03/20/2002 06/17/2002

06/17/200201/30/200309/17/2003

130012001245114012401055113012451245R13301030

17.51418.514.518.513.513.515.6

--

1519.5

>20,000

1,2501,4001,6001,5101,5101,4801,860

--

1,5601,910

20,100

1,3601,3701,6801,5401,5701,9201,8801,8901,5801,780

7.38.17.887.87.87.97.8

--

7.87.7

7.48.18.188.17.98888.18

.69.04

<.02

.03

<.02<.04

.11.05.05

E.04E.03

2.1

.47.39.91.39.29.38.41.43.17.22

<.10<.05<.05<.05<.05<.05

E.03

.19

<.05<.06<.06

<.01<.01<.01<.01<.01<.006

E.007

<.008

E.004

<.008<.008

--

2.7

.08.57

2.252.12.061.981.971.741.23

Appendix D. Summary of water-quality analyses for samples taken from monitoring wells—Continued

Site

number

(figure 3)

Date Time

Temperature

(°C)

Specific

conductance pH

Ammonia

as N

(mg/L)

Ammonia +

organic

nitrogen

as N

(mg/L)

Nitrite +

nitrate(mg/L)

Nitrite

as N

(mg/L)

Total

phosphor

(filtered

mg/L)

Field 

(μS/cm)

Laboratory

(μS/cm)

Field Labora- tory
Appendix D. Summary of water-quality analyses for samples taken from monitoring wells—Continued

Site

number

(figure 3)

Date

Magnesium

as Mg

(mg/L)

Sodium

as

Na

(mg/L)

Potassium

as K

(mg/L)

Alkalinity

as CaC03

(mg/L)

Sulfate

as SO4

(mg/L)

Chloride

as Cl

(mg/L)

Fluoride

as F

(mg/L)

Bromide

as Br

(mg/L)

Silica

as SiO2

(mg/L)

Iron

as Fe

(μg/L)

12 09/14/2000

02/27/200111/20/200106/20/200201/29/200309/16/2003

0.1

.1

--

.1.1.1

----

919496

102

----

32.83.13.2

143144156150164153

35.135.2

--

34.735.934.9

8.58.3

--

98.49.1

0.6

.6

--

.4.4.4

----

0.03

E.02

.04.04

----

34.734.234.335.2

----

E6

136840

13 09/14/2000

02/28/200111/20/200106/20/200201/29/200309/15/2003

2.62.6

--

5.35.25.2

----

40393642

----

77.17.26.4

94

110

98

476

9494

27.736.2

--

37.634.534.4

6.88.1

--

13.413.315.2

.4.4

--

.3.3.4

----

.03.03.04.06

----

27.728.428.529.3

----

<10<10<10

218

14 06/21/1988

06/21/198812/09/199809/21/199902/02/200008/07/200002/28/200103/20/200206/17/200201/28/200306/11/200309/16/2003

7.47.44.75.1

14.8

6.19.4

17

5.5

12.2

--

5.8

31311921

------

392434

--

27

3.63.33.33.8

------

5.33.44.8

--

4.2

99997380

130

8596

212

52

131

--

81

393922.924.751.834.356.860.531.151.3

--

31.9

1819

6.36.2

17.4

7.5

1717.516.218.6

--

12.8

.3.4.2.2.2.3.2.2.2.2

----

--------------

.05.03.04

--

.04

171721.223.5

------

2120.720.9

--

24.5

44

<10<10

------

<10<10<10

--

<8

31 08/02/1988

12/17/199809/22/199902/01/200008/09/200003/14/200106/24/200202/03/200309/19/2003

220261220161181864158152208

3,5004,1503,800

------

2,8302,8802,920

2651.450.7

------

42.943.265.4

1,400

770875920962909831866838

5,2005,1804,7704,2705,1004,6304,6303,9404,430

2,4002,0301,9001,8202,0101,7901,6701,4301,540

1.61.41.81.62.11.51.51.72

------------

2.271.922.1

53.073.076.8

------

58.062.586.8

89

<200

<10

------

111

<100

28E
39 08/02/1988 05/03/1989 08/22/1994 12/15/1998 09/23/1999 01/31/2000 08/08/2000 03/01/2001 03/21/2002 06/18/2002 01/28/2003 09/17/2003 37 140 18024.6 28.9 26.8 32.6 26.5 41.7 39.6 26.6 26.5 230 760 640 247 244------ 333 347 262 244 15222211.9 10.5 ------ 14.2 12.6 11.3 13.6 650 655-- 521 570 532 609 636 709 699 613 488 -- 1,100 1,500 162 214 224 271 171 358 339 193 194 -- 1,000 1,000 54.9 78.4 84.0 115.0 73.9 128.0 136.0 81.5 95.9 --.8 <.10 1.2 1.1 1.2 11.2 1.3 1.3 1.2 1.2 ----.89 ----------.34 .22 .11 .07 14.0 40.0.1 38.1 44.0 ------ 37.3 35.8 38.2 44.5 41430 776 759------ 1,440 1,700 1,060 1,030 50 08/03/1988 09/01/1988 12/11/1998 09/22/1999 02/01/2000 08/08/2000 03/02/2001 03/21/2002 06/18/2002 02/03/2003 09/17/2003 4.0 --9.7 10.9 108.5 7.9 7.2 8.5 12.5 13.5 370-- 288 309------ 226 231 262 242 9.8 -- 14.7 16.1 ------ 10.8 11.4 12.8 14.3 434-- 475 483 501 481 486 375 373 450 393 290-- 249 255 233 191 178 157 154 198 181 120-- 65.6 63.8 57.9 54.2 51.5 45.0 45.8 56.1 59.2 .8 --.7.7.7.8.9.8.7.7.6 --------------.05 E.03 .03 .06 40.0 -- 42.8 44.1 ------ 41.6 42.3 45.0 50.8 70-- <10 <10------ <10 <10 <10<8 64 07/13/1988 12/10/1998 09/21/1999 02/04/2000 08/07/2000 03/01/2001 03/20/2002 06/17/2002 06/17/2002

01/30/200309/17/2003

300

2.42.53.93.53.65.14.74.83.54.6

4,500

291297

------

401398407357391

79

7.78.6

------

1210.310.4

9.6

11.8

852326368492460511489456413453

3,500

99.570.063.673.360.496.5

114113

44.570.1

5,200

191148180171159237237237236251

.3

1.52.01.41.21.31.21.11.2

.8.6

------------

.46.32.34.41.47

31.026.627.0

------

25.724.925.826.329.4

270

5428

------

<10

31312325

Appendix D. Summary of water-quality analyses for samples taken from monitoring wells—Continued

Site

number

(figure 3)

Date

Magnesium

as Mg

(mg/L)

Sodium

as

Na

(mg/L)

Potassium

as K

(mg/L)

Alkalinity

as CaC03

(mg/L)

Sulfate

as SO4

(mg/L)

Chloride

as Cl

(mg/L)

Fluoride

as F

(mg/L)

Bromide

as Br

(mg/L)

Silica

as SiO2

(mg/L)

Iron

as Fe

(μg/L)
Since 1879, the U.S. Geological Survey has been providing maps, reports, and information to help others 

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

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

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

our efforts touch the daily lives of almost everyone.

Maurer and others—EVALUATION OF USGS MONITORING-WELL NETWORK AND POTENTIAL EFFECTS OF CHANGES IN WATER USE, NEWLANDS PROJECT, CHURCHILL COUNTY, NEVADA—USGS, SIR 2004-5246