Trends in Streamflow on the Humboldt River 

between Elko and Imlay, Nevada, 1950–99

Prepared in cooperation with the 

Nevada Department of Conservation and Natural Resources

Scientific Investigations Report 2005-5199

U.S. Department of the Interior

U.S. Geological Survey
FRONT COVER: Photographs of Humboldt River at Blossom bridge near Valmy, Nevada, upstream of

the streamflow gage at Comus. Top photograph is from the bridge looking downstream on June 9, 1999

during high flow. Bottom photograph is from the bridge looking downstream on October 18, 2001 during

a period of no flow. Photographs taken by D.E. Prudic. 
Trends in Streamflow on the Humboldt River 

between Elko and Imlay, Nevada, 1950–99

By David E. Prudic, Richard G. Niswonger, and Russell W. Plume

Prepared in cooperation with the

NEVADA DEPARTMENT OF CONSERVATION AND NATURAL RESOURCES

Scientific Investigations Report 2005–5199

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

P. Patrick Leahy, Acting Director

U.S. Geological Survey, Carson City, Nevada: 2006

For sale by U.S. Geological Survey, Information Services

Box 25286, Denver Federal Center

Denver, CO 80225

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endorsement by the U.S. Government.

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

reproduce any copyrighted material contained within this report.

For additional information contact:

Director

USGS, Nevada Water Science Center

2730 N. Deer Run Road

Carson City, NV 89701 

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

http://nevada.usgs.gov
v

Contents

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

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

Purpose and Scope .....................................................................................................................3

Approach.......................................................................................................................................3

Acknowledgments.......................................................................................................................3

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

Physiography................................................................................................................................3

Climate...........................................................................................................................................6

History of Water Resources Development.......................................................................................8

Surface-Water Diversions for Irrigation..................................................................................8

Ground-Water Withdrawals.....................................................................................................10

Domestic and Municipal Use..........................................................................................11

Irrigation Use.....................................................................................................................11

Industrial Use ....................................................................................................................13

Power Generation....................................................................................................13

Mining Use................................................................................................................13

Streamflow...........................................................................................................................................14

Tributaries ...................................................................................................................................15

Humboldt River...........................................................................................................................21

Annual Precipitation Volume ............................................................................................................31

Method Used ..............................................................................................................................31

Trends .........................................................................................................................................39

Relation of Annual Runoff to Precipitation .....................................................................................39

Tributaries ...................................................................................................................................44

Humboldt River...........................................................................................................................44

Effects of Ground-Water Withdrawals on Annual Runoff............................................................49

Summary and Conclusions................................................................................................................53

References Cited.................................................................................................................................56
vi

Figures

Figure 1. Locations of cultural features including major mines in the Humboldt River Basin, 

north-central Nevada................................................................................................................2

Figure 2. Distribution of mean annual precipitation and locations of streamflow gages and 

weather stations used in analysis of streamflow trends in the Humboldt River 

Basin, north-central Nevada....................................................................................................4

Figure 3. Departures from mean annual precipitation at selected weather stations, water 

years 1950–99 .............................................................................................................................6

Figure 4. Location of irrigated areas, diversions along the Humboldt River, and reservoirs 

on or tributary to the Humboldt River......................................................................................9

Figure 5. Annual volumes of water discharged to the Humboldt River or Maggie Creek 

by mining operations, 1990–99...............................................................................................10

Figure 6. Population trends for counties in the Humboldt River Basin, 1940–99 ...........................11

Figure 7. Number of wells drilled annually for different uses in the Humboldt River Basin 

above Rye Patch Reservoir, 1950–99 ....................................................................................12

Figure 8. Estimates of annual ground-water withdrawals in the Humboldt River Basin 

above Rye Patch Reservoir, 1950–99. ...................................................................................13

Figure 9. Departures from mean annual runoff at streamflow gages on A, Lamoille; 

B, Rock; and C, Martin Creeks, water years 1950–99 ........................................................17

Figure 10. Cumulative annual runoff at streamflow gages on Lamoille, Rock, and Martin 

Creeks, water years 1950–99 .................................................................................................18

Figure 11. Mean monthly discharges at streamflow gages on A, Lamoille; B, Rock; and 

C, Martin Creeks, water years 1950–70, 1971–91, and 1992–99........................................19

Figure 12. Flow duration at streamflow gages on A, Lamoille; B, Rock; and C, Martin 

Creeks, water years 1950–70, 1971–91, and 1992–99 .........................................................20

Figure 13. Departures from mean annual runoff at streamflow gages on Humboldt 

River A, near Elko; B, near Carlin; C, at Palisade; D, at Comus; and E, near 

Imlay, Nevada, water years 1950–99. ...................................................................................22

Figure 14. Cumulative annual runoff at selected streamflow gages on Humboldt River, 

water years 1950–99................................................................................................................24

Figure 15. Differences in cumulative annual runoff between selected streamflow gages 

on Humboldt River, water years 1950–99 .............................................................................25

Figure 16. Differences in cumulative annual runoff between selected streamflow gages 

on Humboldt River compared with cumulative annual runoff at Palisade, 

Nevada, water years 1950–99................................................................................................26

Figure 17. Mean monthly discharges at streamflow gages on Humboldt River A, near 

Elko; B, near Carlin; C, at Palisade; D, at Comus; and E, near Imlay, Nevada, 

water years 1950–70, 1971–91, and 1992–99........................................................................28

Figure 18. Flow duration at streamflow gages on Humboldt River A, near Elko; B, near 

Carlin; C, at Palisade; D, at Comus; and E, near Imlay, Nevada, water years 

1950–70, 1971–91, and 1992–99 ..............................................................................................29

Figure 19. Mean daily discharge at streamflow gages on Humboldt River A, near Elko; 

B, near Carlin; C, at Palisade; D, at Comus; and E, near Imlay, Nevada, 

water years 1950–70, 1971–91, and 1992–99........................................................................30

Figure 20. Mean daily discharges from September through December at streamflow 

gages on the Humboldt River A, near Elko; B, near Carlin; C, at Palisade; D,

at Comus; and E, near Imlay, Nevada, water years 1950–70, 1971–91, and 

1992–99 ......................................................................................................................................31
vii

Figure 21. Distribution of mean annual precipitation and transects used to determine 

regions of different mean annual precipitation with respect to land-surface 

altitude .......................................................................................................................................33

Figure 22. Relation of mean annual precipitation to land-surface altitude by region in 

the Humboldt River Basin. ......................................................................................................34

Figure 23. Departures from mean annual precipitation volume in drainage area above 

streamflow gages on A, Lamoille; B, Rock; and C, Martin Creeks, water years 

1953–99 ......................................................................................................................................40

Figure 24. Departures from mean annual precipitation volume in drainage area above 

streamflow gages on the Humboldt River A, near Elko; B, near Carlin; C, at 

Palisade; D, at Comus; and E, near Imlay, Nevada, water years 1953–99 ......................42

Figure 25. Relation between annual runoff and effective precipitation volume at 

streamflow gages on A, Lamoille; B, Rock; and C, Martin Creeks, water 

years 1955–99 ...........................................................................................................................46

Figure 26. Relation between annual runoff and effective precipitation volume at 

streamflow gages on Humboldt River A, near Elko; B, near Carlin; C, at 

Palisade; D, at Comus; and E, near Imlay, Nevada, water years 1955–99 ......................48

Figure 27. Ratios of annual runoff to effective precipitation volume at streamflow gages 

on A, Lamoille Creek; and B, Rock and Martin Creeks, and effective 

precipitation volume to mean effective precipitation volume above each 

streamflow gage, water year 1955–99 ..................................................................................50

Figure 28. Ratios of annual runoff to effective precipitation volume at streamflow gages 

on Humboldt River, and ratios of effective precipitation volume to mean 

effective precipitation volume above streamflow gages near Carlin and at 

Comus ........................................................................................................................................51
viii

Tables

Table 1. Actively operating streamflow gages as of 1999 in the Humboldt River Basin 

above Imlay, Nevada.................................................................................................................5

Table 2. Weather stations where precipitation was measured between 1950 and 1999 

in the Humboldt River Basin above Imlay, Nevada ............................................................15

Table 3. Drainage areas and percent of areas below and above 6,000 feet altitude for 

streamflow gages on Lamoille, Rock, and Martin Creeks, and on the Humboldt 

River near Elko, near Carlin, at Palisade, at Comus, and near Imlay, Nevada...............16

Table 4. Annual adjustments to the regression equations of mean annual precipitation 

and land-surface altitude by region in the Humboldt River Basin, north-central 

Nevada for water years 1953–99...........................................................................................36

Table 5. Areas of land-surface altitude intervals used to estimate precipitation 

volumes in drainage areas above selected streamflow gages on Lamoille, 

Rock, and Martin Creeks, and on Humboldt River, north-central Nevada .....................37

Table 6. Precipitation volumes estimated for water years 1953–99 in drainage areas 

above selected streamflow gages on Lamoille, Rock, and Martin Creeks, and 

on Humboldt River, north-central Nevada ..........................................................................38

Table 7. Fractions used to estimate effective precipitation volumes on basis of 

partitioning precipitation over three-year periods from 1953 through 1999 in 

drainage areas above streamflow gages on Lamoille, Rock, and Martin 

Creeks, and above streamflow gages on Humboldt River near Elko, near 

Carlin, at Palisade, at Comus, and near Imlay, Nevada.....................................................41

Table 8. Effective precipitation volumes estimated for water years 1955–99 in drainage 

areas above streamflow gages on Lamoille, Rock, and Martin Creeks, and on 

Humboldt River near Elko, near Carlin, at Palisade, at Comus, and near Imlay, 

Nevada.......................................................................................................................................45

Table 9. Annual ground-water withdrawals estimated for water years 1955–99 in 

drainage areas above streamflow gage on Humboldt River near Elko, and 

between selected streamflow gages from Elko to Imlay, Nevada ..................................52

Table 10. Results of multiple linear regression models to estimate runoff at streamflow 

gages along the Humboldt River from Elko to Imlay, Nevada ..........................................54
ix

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 4,047 square meter (m2)

acre 0.004047 square kilometer (km2)

square foot (ft2) 0.09290 square meter (m2)

square mile (mi2) 2.590 square kilometer (km2) 

Volume

cubic foot (ft3) 0.02832 cubic meter (m3) 

acre-foot (acre-ft) 1,233 cubic meter (m3)

Flow rate

acre-foot per year (acre-ft/yr) 1,233 cubic meter per year (m3/yr)

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

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

cubic foot per second per square mile 

(ft3/s)/mi2]

 0.01093 cubic meter per second per square 

kilometer [(m3/s)/km2]

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

°F=(1.8×°C)+32

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

°C=(°F-32)/1.8

Vertical coordinate information is referenced to North American Vertical Datum of 1988 (NAVD

88).

Horizontal coordinate information is referenced to North American Datum of 1983 (NAD 83).

Altitude, as used in this report, refers to distance above the vertical datum.
x
Trends in Streamflow on the Humboldt River between

Elko and Imlay, Nevada, 1950–99

By David E. Prudic, Richard G. Niswonger, and Russell W. Plume

Abstract 

The Humboldt River is an important source of water in 

north-central Nevada. It provides water to several communities 

and is used extensively for agriculture. Farmers began diverting flow from the river in the 1860’s. Conflicts over water 

diversions along the river led to the adjudication of water 

rights and to the construction of Rye Patch Dam and Reservoir 

in the 1930’s. Increased ground-water withdrawals beginning in the 1960’s have raised concerns regarding their effects 

on streamflow. The purpose of this report was to analyze 

streamflow trends from 1950 to 1999 in relation to precipitation and ground-water withdrawals at five streamflow gages on 

the Humboldt River from Elko to Imlay, Nevada.

Effects of ground-water withdrawals have been superimposed on the variation of streamflow caused by climate, which 

during 1950–99 was highly variable. Annual runoff normally 

increased from the streamflow gage near Elko to Palisade 

because of tributary inflow and ground-water discharge, which 

maintained a baseflow during the late summer to early winter. 

Annual runoff normally decreased downstream of Palisade 

because of irrigation diversions, infiltration of streamflow into 

the alluvium, and evapotranspiration. The river often ceased to 

flow downstream of Palisade during late summer because of 

minimal ground-water discharge to its channel.

The ratio of annual runoff to precipitation varied considerably at all streamflow gages with generally higher ratios 

during periods of above mean annual precipitation and lower 

ratios during periods of below mean annual precipitation. 

Highest ratios were estimated for Lamoille Creek, a headwater 

stream in the Ruby Mountains, where the average ratio was 

about 0.7, which indicates that about 70 percent of the precipitation in the drainage area above the streamflow gage became 

runoff. The ratio of runoff to effective precipitation decreased 

downstream along the Humboldt River such that on average 

only 2 percent of the annual precipitation in the drainage area 

above the streamflow gage near Imlay, Nevada became runoff. 

This implies that 98 percent of the annual precipitation was 

lost to evapotranspiration or to ground-water storage.

Ground-water withdrawals above the streamflow gage

at Palisade had no significant effect on annual runoff above 

Palisade on the basis of multiple linear regressions that 

included annual runoff at an upstream gage, and annual 

precipitation volumes and ground-water withdrawals between 

streamflow gages. Ground-water withdrawals between Palisade and Comus had no significant effect on annual runoff 

to a probability of 0.05 at Comus until 1992, when discharge 

of water directly to the river from mining operations had 

a significant effect that slightly increased annual runoff at 

Comus. Ground-water withdrawals in the reach between 

Comus and Imlay were significant to a probability of 0.04 and 

slightly decreased annual runoff at Imlay. Most ground-water 

withdrawals in the reach between Palisade and Comus were 

in alluvial basins distant from the river, whereas much of the 

ground-water withdrawals in the reach between Comus and 

Imlay were either near the mouths of alluvial valleys adjacent 

to the Humboldt River Valley or the withdrawals were within 

the valley proper.

Introduction 

The Humboldt River Basin covers an area of nearly 

17,000 mi2 in Nevada, and it is the only major river basin that 

is entirely in the State (fig. 1). Streamflow of the Humboldt 

River and its tributaries and ground water are used by diverse 

and sometimes competing interests. Streamflow historically 

has been used for agricultural purposes—mainly irrigation 

of crops and meadows. However, wetlands along the river 

and its tributaries provide wildlife habitat, and infiltration 

of streamflow is a source of recharge to underlying aquifers. Prior to 1980, most ground-water withdrawals in the 

Humboldt River Basin were for municipal and domestic use, 

irrigation of crops, watering stock, and industrial use at a few 

mines. Since 1990, ground-water withdrawals in the basin 

have increased as a result of development of large gold mines 

and a corresponding increase in population.

Federal, State, and local government agencies and other 

groups are concerned about the long-term viability of the 

water resources of the Humboldt River Basin because of the 

increased demand for ground water and the need to dewater 

several of the gold mines. (The word “dewater” as used in this 

report refers to the pumping of ground water for the purpose 
Figure 1. Locations of cultural features including major mines in the Humboldt River Basin, north-central Nevada.

Area of figure 4 

LANDER COUNTY

EL KO COUNT Y

WH IT E PI NE COUNT Y

PE RSHING COUNT Y

CHUR CHI LLCOUNT Y

HUMBO LD T COUNT Y

PERSHING COUNT Y

LA

EUREKA COUNTY 

NDER COUNTY 

NYE COUNTY 

MINERAL COUNTY 

CHURCHILL COUNTY 

11 6o

11 5o

39o

40o

11 9o

41o

11 8o

11 7o

Rye Patch 

Reservoir

River

Ruby Mountains 

Elko 

Carlin 

Humboldt

Lovelock 

Humboldt

Sink

River

Humboldt

Battle

Mountain

Palisade 

Winnemucca 

Golconda 

Imlay 

Argenta

Dunphy 

Humboldt

Martin

Creek 

River

Marys River

North

Fork Humboldt River

Maggie 

Creek 

Willow Creek 

Marys

Creek 

Susie

Creek Little

Reese

River

Rock 

Creek 

Pine

Creek 

Santa Rosa Range 

Tuscarora 

Mountains

Jarbidge 

Mountains

East

Humboldt

Range

In dependence

Mounta ni s

Lovelock 

Valley 

Toiyabe

Range

Lamoille Creek

South Fo

H

rk

untington Creek

Bishop Creek 

Bishop Creek 

Willow Reservoir

Creek 

Reservoir

0

0 2 10 0 4 30 0 50 KILOMETERS

10 20 30 40 50 MILES

EXPLANATION 

Hydrographic-area boundary 

Active mine—Not dewatered in 1998 

Active mine—Dewatered in 1998 

Active mine—Water released to Humboldt 

 River or tributary in 1998 

. 

. 

Las 

Vegas 

Reno 

Area of figure 

(Humboldt River Basin) 

NEVADA 

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

1977-88; Universal Transverse Mercator projection

Zone 11; Shaded-relief base from 90-meter Digital

Elevation Model; sun illumination from northwest at

30 degrees above horizon

2 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
of lowering water levels in order to maintain a dry and workable mine). In response to this concern, the U.S. Geological 

Survey (USGS), in cooperation with the Nevada Department 

of Conservation and Natural Resources (NDCNR), has undertaken the Humboldt River Basin Assessment. The objectives 

of the assessment are to (1) provide scientific appraisals of 

the ground-water and surface-water resources of each hydrographic area in the Humboldt River Basin, (2) determine the 

contribution of each area to the quantity and timing of flow in 

the Humboldt River, and (3) determine the effects of all major 

water uses in the basin.

Purpose and Scope

The purposes of this report are threefold. The first was to 

evaluate streamflow conditions and trends on the Humboldt 

River and three of its tributaries during 1950–99. This period 

was used for the flow analysis because several streamflow 

gages were in continuous operation since the mid-1940’s 

(table 1). The second purpose was to determine the variation 

in annual runoff in relation to precipitation. The third purpose 

was to evaluate the effects of ground-water withdrawals on 

annual runoff. 

Streamflow records for Lamoille and Martin Creeks were 

particularly important for this analysis because neither of these 

drainages have been affected by man’s activities to the extent 

experienced by the other drainages in the Humboldt River 

Basin. Thus, any short-term or long-term changes in the flow 

of either stream during 1950-99 were the result of climate 

variability. Contrastingly, streamflow along the Humboldt 

River and several other tributaries have been affected during 

the past 140 years or so by numerous irrigation diversions, 

construction of reservoirs, channel modification, and, most 

recently, by the discharge of water to the Humboldt River and 

to Maggie Creek from mining operations.

Approach

The results of this study are based on streamflow and 

precipitation data collected during water years 1950–99. Water 

year used herein is the 12-month period October 1 through 

September 30. The water year is designated by the calendar 

year in which the 12-month period ends. These data consist of 

daily mean discharges at five streamflow gages on the main 

stem of the Humboldt River between Elko and Imlay and at 

three streamflow gages on Lamoille, Rock, and Martin Creeks 

(fig. 2 and table 1). Daily mean discharges for each gage were 

obtained from the USGS National Water Information System 

on the World Wide Web (WWW) at http://waterdata.usgs.

gov/nv/nwis/nwis. The data also consist of precipitation measured at 36 weather stations in or adjacent to the Humboldt 

River Basin (fig. 2). Daily precipitation and temperature 

were obtained from the National Oceanic and Atmospheric 

Administration, National Climatic Data Center (1999) and 

from the Natural Resources Conservation Service (1999) and 

twice annual precipitation was obtained from high-altitude 

precipitation-storage gages from the Nevada Division of Water 

Resources (NDWR), State Engineer’s Office (Carson City, 

Nevada, written commun., 2000).

The streamflow data were analyzed with graphical 

methods using annual runoff, mean monthly, and mean daily 

discharges separated into three periods (1950–70; 1971–91; 

and 1992–99) that represent changes in the volumes and 

distribution of ground-water withdrawals. Annual volumes of 

precipitation were estimated using the measurements from the 

weather stations and by dividing the Humboldt River Basin 

into regions that had different mean annual precipitation in 

relation to land-surface altitude. Multiple linear regression 

techniques were used to determine the relation between annual 

runoff and precipitation volume at each of the streamflow 

gages, and to evaluate the effects of ground-water withdrawals 

on annual runoff at streamflow gages on the Humboldt River.

Acknowledgments

Several people contributed to the study. Matt Dillon, Kim 

Groenwald and other employees from the Nevada Division of 

Water Resources provided assistance for obtaining information on water use, drillers’ logs, and streamflow diversions. 

Information from drillers’ logs and crop inventories from 

the Nevada Division of Water Resources was entered into an 

Excel spreadsheet by Katherine K. Henkelman (USGS) and 

provided important information on the history of groundwater development. Information on county and city population 

demographics from 1950 to 1999 was compiled by Rachel M. 

Caskey (USGS) from information from the U.S. Bureau of the 

Census (1952, 1983, 1991, and 2003) and from the Nevada 

State Demographer (Jeff Hardcastle, Reno, Nevada, written 

commun., 2005).

The USGS principal cooperator for the Humboldt River 

Basin Assessment has been the Nevada Department of Conservation and Natural Resources. However, financial support 

has been provided by the mining industry and state and local 

government. Support from the mining industry has come from 

Barrick Gold Corporation, Newmont Mining Corporation, 

Santa Fe Pacific Gold Corporation, Glamis Gold Limited, 

and Getchell Gold Corporation. Support from state and local 

government has come from Nevada’s Legislative Committee 

on Public Lands, Nevada Division of Water Resources, Eureka 

County, and the Humboldt River Basin Water Authority.

Geographic Setting

Physiography

The headwaters of the Humboldt River are in the Ruby, 

Jarbidge, and Independence Mountains and East Humboldt 

Range in northeastern Nevada (fig. 1). The main stem of the 

river receives flow from several tributaries including Marys 

River, the North Fork Humboldt River, Lamoille Creek, the 

Geographic Setting 3
Figure 2. Distribution of mean annual precipitation and locations of streamflow gages and weather stations used in analysis of 

streamflow trends in the Humboldt River Basin, north-central Nevada. Mean annual precipitation was estimated for 1960–91 by Daly 

and others (1994) for all of Nevada. Estimates of mean annual precipitation for a 2.4 square mile grid were provided by G.H. Taylor 

(Oregon Climate Service, Oregon State University, written commun., 1997).

Imlay 

Comus 

Martin Creek 

Rock Creek 

6 

10 

12 

15 

1 

18 

21 

25 

36 

8 

20 

30 

4 

22 

33 

27 

35 

11 

7 19 

14 

17 

13 

29 

28 

32 

Lamoille Creek 

2 

3 

Imlay 

Comus 

 Comus

Martin Creek 

Rock Creek 

Palisade 

5 

4 

6 

26 

10 

12 

15 

1 

18 

21 

25 

36 

8 

16 

9 

8 

20 

30 

Elko 

Palisade 

4 

22 

23 

33 

27 

34 35 

11 

7 19 

14 

17 

13 

29 

31 

28 

24 

32 

1 

Lamoille Creek 

2 

3 

Jarbidge 

Mountains

Independence

0 20 40 60 MILES 

0 20 40 60 KILOMETERS 

39°

40°

41°

119°

118°

117°

116°

115°

Base from U.S. Geological Survey digital data 1:100,000, 1977-1988 

Universal Transverse Mercator projection, Zone 11, NAD 27 

Shaded-relief base from 90-meter Digital Elevation Model; 

sun illumination from northwest at 30 degrees above horizon 

EXPLANATION 

Weather Station and number—See

 table 2 

National Weather Service 

Natural Resources Conservation Service 

Nevada Department of Conservation 

 and Natural Resources 

Gage and abbreviated name—See table 1

Mean annual precipitation, in inches 

36 – 44

29 – 36

21 – 28

13 – 20

 6 – 12

Rye Patch 

Reservoir

River

Ruby Mountains 

Carlin 

Humboldt Humboldt Sink

River

Humboldt

Reese

River

Santa Rosa Range 

Tuscarora 

Mountains

East

Humboldt

Range

Lovelock 

Valley 

Toiyabe

Range

Mountains

4 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
South Fork Humboldt River, and Susie, Maggie, Marys, and 

Pine Creeks, and occasionally from Rock Creek and the Reese 

and Little Humboldt Rivers (fig. 1). 

The study area consists of the main stem of the Humboldt 

River from the streamflow gage near Elko to the streamflow 

gage near Imlay, a distance along the river channel of 307 

mi (fig. 2). This reach of the river includes the uppermost 

streamflow gage on the river (near Elko) to the lower most 

streamflow gage (near Imlay) that is above Rye Patch Reservoir. The study area also includes three of its tributaries—

Lamoille, Rock, and Martin Creeks (fig. 2).

Land-surface altitudes in lowlands of the Humboldt River 

Basin range from less than 3,900 ft at the Humboldt Sink in 

the western part of the basin to more than 5,000 ft in the eastern part. Land-surface altitudes in mountain ranges are more 

than 11,000 ft in parts of the Ruby Mountains, East Humboldt 

Range, and the southern Toiyabe Range. The terms low-altitude and high-altitude are used to refer to runoff sources for 

the streamflow gages discussed herein. Low-altitude areas are 

at altitudes of less than 6,000 ft and high-altitude areas are at 

altitudes above 6,000 ft.

The Humboldt River flows through a broad valley from 

northeast to southwest. This valley is several miles wide and is 

well defined where it is bounded by mountain ranges, and less 

well defined at the mouths of large tributary valleys such as 

those of the Reese and Little Humboldt Rivers. The Humboldt 

Table 1. Actively operating streamflow gages as of 1999 in the Humboldt River Basin above Imlay, Nevada

[Shaded stations are those shown in figure 2 and discussed in this report. Data for each streamflow gage can be obtained from http://waterdata.usgs.gov/nv/nwis/]

Station 

Number Station Name

Drainage Area

(square miles)1

Annual runoff for 

period of record

to 1999 2

 (acre-feet)

Period of Record to

 water year 1999

10313400 Marys River Below Orange Bridge near Charleston 72 36,210 1991 to 1999

10315500 Marys River above Hot Springs Creek, near Deeth 415 47,770 1943 to 1980, 1982 to 1999

10315600 Marys River below Twin Buttes near Deeth 516 42,100 1991 to 1999

10316500 Lamoille Creek near Lamoille 25 32,870 1915 to 1923, 1943 to 1999

10318500 Humboldt River near Elko 2,780 186,600 1895 to 1902, 1944 to 1999

10319900 South Fork Humboldt River above Tenmile Creek near 

Elko 898 92,110 1989 to 1999

10320000 South Fork Humboldt River above Dixie Creek, near 

Elko 1,150 87,560 1948 to 1982, 1988 to 1999

10321000 Humboldt River near Carlin 4,340 278,700 1943 to 1999

10321590 Susie Creek at Carlin 194 7,420 1992 to 1999

10321925 Simon Creek near Highway 766 near Carlin 46 980 1996 to 1997

10321940 Maggie Creek above Maggie Creek Canyon near Carlin 332 25,010 1997 to 1999

10321950 Maggie Creek at Maggie Creek Canyon near Carlin 334 16,270 1989 to1999

10322000 Maggie Creek at Carlin 396 22,870 1913 to 1924, 1992 to1999

10322150 Marys Creek at Carlin 45 4,210 1989 to 1999

10322500 Humboldt River at Palisade 5,050 291,900 1902 to 1906, 1911 to 1999

10323425 Humboldt River at Old U.S. 40 Bridge, at Dunphy 7,390 329,100 1991 to 1999

10324500 Rock Creek near Battle Mountain 864 29,700 1918 to 1925, 1927 to 1929,

1945 to 1999

10324700 Boulder Creek near Dunphy 77 62 1991 to 1999

10325000 Humboldt River at Battle Mountain 8,860 272,100 1896 to 1897, 1921 to 1924,

1945 to 1981, 1991 to 1999

10327500 Humboldt River at Comus 12,200 247,400 1884 to 1926, 1945 to 1999

10329000 Little Humboldt River near Paradise Valley 1,030 16,660 1921 to 1928, 1943 to 1999

10329500 Martin Creek near Paradise Valley 175 25,430 1921 to 1999

10333000 Humboldt River near Imlay 15,500 207,700 1935 to 1941, 1945 to 1999

1 Drainage area rounded to three significant figures or to nearest square mile when less than 100 (from Stockton and others, 2004).

2 Annual runoff for period of record to water year 1999 reported by Jones and others (2000).

Geographic Setting 5
hot summers, and arid conditions (2) mid-latitude steppe, 

with cold winters, hot summers, and semi-arid conditions; 

(3) subhumid continental, with cold winters and moderate 

precipitation; and (4) humid continental with cold winters and 

heavy precipitation. Mid-latitude desert and steppe climate 

types generally correspond to lowlands in the Humboldt River 

Basin. The subhumid continental climate type generally corresponds to mountain ranges. The humid continental type is 

restricted to the highest parts of the mountains in the eastern 

part of the Humboldt River Basin. This latter climate type 

covers only a small part of the basin, but accounts for a large 

percentage of the total runoff of the Humboldt River in most 

years.

Mean annual precipitation at the three long-term weather 

stations at or above 6,000 ft ranged from 13.17 in. at Austin 

to 16.12 in. at Lamoille, whereas mean annual precipitation at four long-term weather stations in the basin lowlands 

River passes through four canyons—the first near Elko, the 

second near Carlin, the third near Palisade, and the fourth 

above Golconda (fig. 1).

Climate

The flow of the Humboldt River depends almost entirely 

on the annual snowpack that accumulates each winter in the 

Ruby, Jarbidge, and Independence Mountains, and the East 

Humboldt Range (fig. 2). Mean annual precipitation ranges 

from about 6 in. near the Humboldt Sink to more than 36 in. 

in the Ruby Mountains (fig. 2). Year-to-year and longer-term 

variations in annual precipitation result in corresponding variations in flow of the river.

The Humboldt River Basin is characterized by four 

climatic types (Houghton and others, 1975, p. 3), which can 

be described as (1) mid-latitude desert, with cold winters, 

Figure 3. Departures from mean annual precipitation at selected weather stations, water years 1950–99. Weather stations are listed 

in table 2 and shown in figure 2. (Precipitation data are from the National Oceanic and Atmospheric Administration, National Climatic 

Data Center, 1999.) 

Mean annual precipitation = 16.12

Coefficient of variation = 0.23 

Median annual precipitation = 16.77 

WATER YEAR

DEPARTURE FROM MEAN ANNUAL PRECIPITATION, IN PERCENT 

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 1999

-100

0

100

Austin—Altitude 6,605 feet 

Mean annual precipitation = 13.17

Coefficient of variation = 0.30 

Median annual precipitation = 13.19 

0

100 Lamoille—Altitude 6,310 and 5,840 feet 

-100

-100

0

100 Arthur 4NW—Altitude 6,299 feet 

Mean annual precipitation = 14.73 

Coefficient of variation = 0.28 

Median annual precipitation = 14.50

6 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
(between 4,300 ft to almost 5,100 ft altitude) ranged from 8.06 

in. at Battle Mountain to 9.63 in. at Elko for the 50-yr period 

from 1950 to 1999 (fig. 3). Lower coefficients of variation 

(standard deviation divided by the mean annual precipitation) 

were estimated for the stations on the eastern side of the basin 

indicating that precipitation is generally less variable than to 

the west. The least coefficient of variation was determined for 

the weather station at Lamoille on the west side of the Ruby 

Mountains suggesting that the high mean annual precipitation 

areas (areas in fig. 2 with mean annual precipitation greater 

than 20 in.) may have less variability than areas with less mean 

annual precipitation.

The 1950’s through the early 1960’s were characterized by two droughts as indicated by the negative departures 

from mean annual precipitation (fig. 3). The severity of both 

droughts was greater in western parts of the Humboldt River 

Basin where precipitation during some years was less than half 

of the 50-yr mean. The 1950’s were preceded by a wetter than 

average period over much of the Humboldt River Basin. The 

wetter period of above mean annual precipitation started in the 

late 1930’s and continued into the 1940’s (Eakin and Lamke, 

1966, p. 19). The 1960’s through the 1970’s had several alternating periods of generally above and below mean annual precipitation. The wet years from 1982 to 1984 were well above 

mean annual precipitation at most stations, sometimes as much 

as 50 percent or more and increased precipitation was not limited to the higher elevations as shown by the large departures 

at Elko, Beowawe, and Winnemucca. The effect of these three 

wet years was that the annual runoff of the Humboldt River in 

1984 was the largest ever recorded at all the streamflow gages. 

WATER YEAR

DEPARTURE FROM MEAN ANNUAL PRECIPITATION, IN PERCENT 

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 1999

-100

0

100 Winnemucca Municipal Airport—Altitude 4,297 feet 

Mean annual precipitation = 8.10 

Coefficient of variation = 0.31 

Median annual precipitation = 8.09 

-100

0

100 Battle Mountain—Altitude 4,450 feet 

Mean annual precipitation = 8.06 

Coefficient of variation = 0.31 

Median annual precipitation = 8.02

-100

0

100 Beowawe—Altitude 4,700 feet 

Mean annual precipitation = 8.43 

Coefficient of variation = 0.32 

Median annual precipitation = 8.45

-100

0

100 Elko Airport—Altitude 5,050 feet 

Mean annual precipitation = 9.63

Coefficient of variation = 0.29 

Median annual precipitation = 9.35

Geographic Setting 7

Figure 3. Continued. 
The wet years of 1982–84 were followed by a drought 

that began about 1985 and continued through 1994. The 

severity of this drought differed across the Humboldt River 

Basin and was most pronounced at the three eastern stations 

near the Ruby Mountains (Arthur 4NW, Lamoille, and Elko) 

and at Winnemucca. The greater severity of the drought in the 

eastern part of the basin is where much of the annual runoff in 

the Humboldt River is generated. The mid to late 1990’s was 

generally above mean annual precipitation at the four lowaltitude stations. During this same period, each of the three 

high-altitude stations had two years of below mean annual 

precipitation.

History of Water Resources 

Development

Surface-Water Diversions for Irrigation

Diversion of flow from the Humboldt River and its 

tributaries for irrigating meadows and crops is, and has been, 

the principal use of surface water in the Humboldt River 

Basin. The first large ranching operations in the basin were 

established between about 1862 and 1872 (Horton, 2000, 

p. 102–103). The completion of the Transcontinental Railroad was particularly important to the establishment of these 

operations because the railroad was needed for transportation of cattle to markets. During high flows of spring and 

early summer, the river overtops its banks and spreads out in 

abandoned channels, and thus naturally irrigates low lying 

meadows. Ranchers and farmers began diverting water into 

canals and ditches for irrigation of crops and meadows. The 

first diversions, based on year of priority, were put into use 

in the Lovelock area in 1861, in the Elko area in 1862, and 

the Winnemucca and Imlay areas in 1863 (Hennen, 1964b, p. 

154, 170, 177, and 178). By the late 1800’s, diversions on the 

upper Humboldt River were so prolific that streamflow rarely 

reached the Lovelock area in average or dry years (Horton, 

2000, p. 108–109). Conflicts between upstream and downstream users continued to intensify in the early 1900’s, and 

this led not only to the adjudication of Humboldt River water 

rights in the 1930’s (Mashburn and Mathews, 1943), but also 

to construction of Rye Patch Dam and Reservoir (fig. 4) in 

1935–36.

The process of water-rights adjudication on the 

Humboldt River began with the filing of the Nevada State 

Engineer’s Final Order of Determination in the District Court 

of Humboldt County and it included the Bartlett Decree, 

intervening orders by two other judges, and a final decision 

by the Nevada Supreme Court ending litigation (Mashburn 

and Mathews, 1943). Besides establishing priorities by year 

for individual water rights, the adjudication established two 

districts on the river with irrigation seasons of differing length, 

and identified three crop types and irrigation requirements for 

each. Figure 4 shows locations of diversions on the main stem 

of the river as of the early 1990’s.

The upper district on the Humboldt River is that part of 

the basin upstream from the streamflow gage at Palisade and 

the lower district extends from Palisade to Lovelock Valley (Malone, 1932, p. 13). The irrigation season in the upper 

district extends from April 15 to August 15 each year and in 

the lower district from March 15 to September 15. The three 

recognized crop types and water requirements are (1) harvest lands—3 ft/yr; (2) meadow pasture—1.5 ft/yr; and (3) 

diversified pasture—0.75 ft/yr. The Bartlett Decree recognized 

that the total cultivated area using water from the Humboldt 

River was 285,238 acres (Mashburn and Mathews, 1943, p. 

27). The decree further recognized that 698,379 acre-ft would 

be required to satisfy all water rights with a priority of 1928 

or earlier (Mashburn and Mathews, 1943, p. 28). Because 

the average annual flow of the river at Palisade at the time 

of the decree was 255,650 acre-ft (Mashburn and Mathews, 

1943, p. 28), serving all water rights in a year of average flow 

depended on irrigation return flows to the river (Hennen, 

1964a, p. 13). As of 1963, 265,791 acres of land with decreed 

water rights of 666,680 acre-ft were under irrigation in the 

Humboldt River Basin (Hennen, 1964a, p. 8). As of 2000, 

270,978 acres of land with decreed water rights of 674,581 

acre-ft were under irrigation (Horton, 2000, p. I–99). These 

figures do not include lands irrigated by diversions from the 

Reese River and the Little Humboldt River because both of 

these streams rarely reach the Humboldt River, and thus have 

no consistent influence on its flow.

Prior to 1910, the Humboldt River followed a course in 

its reach between Dunphy and Battle Mountain that now is one 

to three miles north of its present course. The older channel 

was abandoned as a result of flooding during February and 

March 1910 (Foster, 1933, p. 49–50). Blue House Slough and 

the lowest reaches of Rock Creek mark the abandoned course 

(fig. 4). After 1910, the present channel was well defined 

except for a marshy area near Argenta that was called the 

Argenta Swamp. In this area, the river channel disappeared 

and flow spread out over an area of marshes and wetlands. 

Estimates of the total area of the Argenta Swamp have ranged 

from less than 1,000 acres (Malone, 1932, p. 41–48) to 

12,000–15,000 acres (Horton, 2000, p. 24). Flow of the river 

exited the Argenta Swamp as two channels that joined a few 

miles east of Battle Mountain (Foster, 1933, p. 50–51). The 

effect of the Argenta Swamp was that it impeded the flow 

of the river, especially in the spring, and delayed the arrival 

of the snowmelt runoff in the Lovelock area. Flow losses in 

this reach of the river were estimated to range from 4,000 to 

12,000 acre-ft/yr mainly because flow had to resaturate the 

shallow water table in the swamp area before it could continue 

downstream (Malone, 1932, p. 48). Lovelock area irrigation 

interests and the Bureau of Reclamation began to consider 

draining the swamp during the 1930’s, but this was not accomplished until the early 1950’s when a ditch was constructed to 

drain the swamp. The ditch is visible from I-80 as a straight 

section of river channel north of the highway and immediately 

west of the Argenta railroad siding.

8 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
Figure 4. Location of irrigated areas, diversions along the Humboldt River, and reservoirs on or tributary to the Humboldt River.

116o

39o

40o

41o

11 8o

117o

Rye Patch 

Reservoir River

Ruby Mountains 

Elko 

Dunphy 

Lovelock 

Humboldt

Humboldt

Sink

River

Humboldt

Battle

Mountain

Palisade 

Winnemucca

Imlay 

Argenta

#

#

Lovelock 

Valley 

Rock Creek

Paradise Valley 

Grass Valley 

Golconda

Chimney 

Reservoir 

Willow 

Creek 

Reservoir 

 Maggie 

Creek 

Reservoir 

T-S Ranch 

Reservoir 

Blue House 

Slough 

Canal 

South Fork 

Reservoir 

Upper and

Lower Pitt-Taylor

Reservoirs

Pitt-Taylor

Diversion

Canal

Iron Point 

Relief Canal 

and Herrin 

Slough 

Lone Tree 

cooling ponds 

Valmy 

power 

plant

Lone

Tree 

Beowawe 

power 

plant

Betze 

Gold

Quarry 

Sand dunes

0

0 10 20 30 KILOMETERS 

10 20 30 MILES 

EXPLANATION 

Hydrographic-area boundary 

Diversion 

Reservoir 

Diversion from the Humboldt River or 

one of its tributaries 

Area irrigated by: 

Ground water 

Active mine—Not dewatered in 1998 

Active mine—Dewatered in 1998 

Active mine—Water released to Humboldt 

 River or tributary in 1998 

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

1977-88; Universal Transverse Mercator projection 

Zone 11 

History of Water Resources Development 9
Ten reservoirs store water in the Humboldt River Basin 

(figs. 1 and 4). Three are used to store ground water pumped 

for mine dewatering purposes and seven impound streamflow 

for irrigation and recreation purposes. Maggie Creek and T-S 

Ranch Reservoirs and Lone Tree Cooling Ponds store excess 

ground water pumped from the Gold Quarry, Betze-Post, and 

Lone Tree Mines, respectively. Figure 5 shows discharge volumes from each of the mine-dewatering storage reservoirs for 

water years 1990–99. Water from Maggie Creek Reservoir has 

been released to the Humboldt River by way of Maggie Creek 

since April 1994 at total annual volumes ranging from 8,840 

acre-ft in 1994 to 19,000 acre-ft in 1997. The total volume discharged to Maggie Creek as of 1999 was 84,400 acre-ft. Water 

from the T-S Ranch Reservoir was released to the Humboldt 

River by way of a lined canal and pipeline (fig. 4) in 1997–99 

at total annual volumes of 24,600 acre-ft, 48,600 acre-ft and 

8,600 acre-ft, respectively. Total water released to the river 

from the T-S Ranch Reservoir as of 1999 was 81,800 acre-ft. 

Water from the Lone Tree Cooling Ponds has been released to 

the Humboldt River by way of a lined ditch, Iron Point Relief 

Canal, and Herrin Slough since June 1992 at total annual volumes ranging from 13,100 acre-ft in 1992 to 45,700 acre-ft in 

1999. The total volume released to the Iron Point Relief Canal 

as of 1999 was 289,000 acre-ft. However, the volume that 

reached the Humboldt River by way of Herrin Slough probably was less because of seepage and evaporation losses. As 

of 1999, total ground water released to the Humboldt River, 

either directly or by way of tributaries, was 455,000 acre-ft 

(Data source for all releases from NDWR files, 2003).

Four reservoirs impound streamflow on tributaries to the 

Humboldt River and three reservoirs impound water along or 

near the main stem of the Humboldt River (figs. 1 and 4). The 

four reservoirs on tributaries are (1) Bishop Creek Reservoir, 

with a potential capacity of 30,000 acre-ft and constructed in 

1912, is not used because of structural problems; (2) South 

Fork Reservoir, with a capacity of 42,000 acre-ft and constructed in 1987, is used for recreation and fisheries purposes; 

(3) Willow Creek Reservoir, with a capacity of 18,000 acre-ft 

and constructed during 1910–25, is used for irrigation; and 

(4) Chimney Reservoir, with a capacity of 35,000 acre-ft and 

constructed in 1974, is used for irrigation and recreation. The 

three reservoirs on or near the Humboldt River are downstream of Imlay and are used for irrigation in the Lovelock 

area. The Upper and Lower Pitt-Taylor Reservoirs have a 

combined capacity of 36,600 acre-ft and were constructed 

during 1907–11. These two reservoirs are filled by way of 

the Pitt-Taylor diversion canal only when no storage capacity is available in Rye Patch Reservoir. Rye Patch Reservoir 

was constructed during 1935–36 and has a storage capacity of 

194,300 acre-ft. It is the only impoundment on the main stem 

of the Humboldt River. This reservoir is also used for recreation. Total usable impoundment capacity in the Humboldt 

River Basin is about 326,000 acre-ft. However, this capacity 

is achieved only during the infrequent periods of well above 

average precipitation and runoff in the Humboldt River Basin.

Ground-Water Withdrawals

Ground water is, and historically has been, pumped in the 

Humboldt River Basin to meet the demands for five principal 

uses—municipal and domestic, power generation, irrigation, 

mining, and stock. Power generation and mining use traditionally have been reported as industrial use. The development 

history of ground-water resources in the Humboldt River 

Basin from the late 1800’s to the 1940’s cannot be accurately 

documented because few records were kept. However, census 

records from the U.S. Bureau of the Census (1952, 1983, 

1991, and 2003) and the Nevada State Demographer (Jeff 

Hardcastle, Reno, Nevada, written commun., 2005) combined 

with well drillers’ reports from NDWR (Carson City, Nevada, 

written commun., 2002) provide useful information for making estimates of ground-water withdrawals prior to the time 

when records were begun in the 1980’s.

Figure 5. Annual volumes of water discharged to the Humboldt 

River or Maggie Creek by mining operations, 1990–99. Location of 

mines is shown in figure 4. (Data are from Nevada State Division 

of Water Resources, State Engineer’s Office, written commun., 

2002; Newmont Mining Corporation, written commun., 2004; and 

Barrick Gold Corporation, written commun., 2004.)

 

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&%%40%29%!2

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10 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
Populations in the counties that are included in the 

Humboldt River Basin were nearly static from 1940 to 1960 

(fig. 6) on the basis of the decadal census suggesting that 

there were few changes in development of the water resources 

resulting from a change in population (both surface and 

ground water). Populations in all counties in the Humboldt 

River Basin increased slowly from 1960 to 1980 and correspond to a period when people settled several areas in the 

Humboldt River Basin, drilled wells, and began irrigating 

crops. Populations increased dramatically after 1980 as a 

result of the development of large, low-grade gold deposits 

and the resultant employment opportunities.

Numbers and types of wells drilled each year since 1949 

provided another indication of the development of groundwater supplies. The number of wells drilled each year by 

type of use is shown in figure 7. The number of wells drilled 

for stock water remained relatively low throughout the 50-yr 

period with the number of wells drilled increasing during 

dry periods (1953–60; 1968; 1977; 1981; 1988–92). Only a 

few irrigation wells were drilled between 1949 and 1958 and 

most were for supplemental irrigation when surface water 

was insufficient. However, many irrigation wells were drilled 

between 1958 and 1977 when people began settling areas 

away from the Humboldt River (see fig. 4 for location of areas 

irrigated with ground water). The number of domestic wells 

drilled annually remained low until 1977 when the number 

of wells drilled doubled. There was another large increase 

in the number of domestic wells drilled starting in 1988 that 

continued until 1998. The large increase in the number of 

domestic wells beginning in 1988 coincides with a rapid 

increase in population in most counties in the Humboldt River 

Basin (compare figs. 6 and 7). Similar trends occurred with 

the drilling of monitoring and test wells for gold exploration 

and mining and for municipal and industrial (power generation 

and mining) uses that also coincide with a rapid increase in 

population.

The number of wells drilled for municipal and industrial 

use declined dramatically after 1998, which corresponds to a 

decline in the number of new gold mining operations and in 

the general population for Elko, Humboldt, and Lander Counties (compares figs. 6 and 7). The decline in new gold mining 

operations also corresponds to a decline in the number of wells 

drilled for domestic, monitoring, and test purposes after 1996 

that preceded the decline in population.

Domestic and Municipal Use

Estimates of ground-water withdrawals for domestic and 

municipal uses were based on the years between 1988 and 

1999 when municipal water use was reported. Comparison of 

municipal use with the municipal population served for these 

years provided an approximate per capita water use of 0.4 

Figure 6. Population trends for counties in the Humboldt River 

Basin, 1940–99. Data from U.S. Bureau of the Census (1952, 1983, 

1991, and 2003), and Nevada State Demographer (Jeff Hardcastle, 

Reno, Nevada, written commun., 2005).

acre-ft/yr. This value was then used to estimate total municipal use on the basis of municipal populations. Domestic water 

use was estimated on the basis of the rural population in 1950. 

It was increased yearly on the basis of the number of new 

domestic wells drilled every year in each county multiplied 

by the product of the average number of people per household 

and the per capita water use. The total estimated municipal 

and domestic water use ranged from less than 10,000 acre-ft 

in 1950 to more than 20,000 acre-ft in 1999 (fig. 8).

Irrigation Use

Estimates of ground-water withdrawals for irrigation 

were based on several sources. Only Paradise Valley north of 

Winnemucca had annual estimates that extended for 1950–99 

(Prudic and Herman, 1996; and crop inventories from 

NDWR). Annual ground-water withdrawals in other areas 

of the Humboldt River Basin above Imlay were estimated 

from previous reports (Eakin, 1961; Zones, 1961; Eakin, 

1962; Cohen, 1963; Crosthwaite, 1963; Cohen, 1964; Eakin 

and others, 1965; Everett and Rush, 1966; Rush and Everett, 

1966; Eakin and others, 1976; and Harrill and Prudic, 1998); 

from maps and air photos showing irrigated acreages during 

the mid-1970’s, from crop inventories compiled annually by 

NDWR since the early 1980’s, and from well drillers’ reports 

YEAR

0

10

20

30

40

50

60

70

80

90

1940 1950 1960 1970 1980 1990 2000

POPULATION, IN THOUSANDS 

All

Elko

Eureka

Lander

Humboldt

Pershing

History of Water Resources Development 11
Figure 7. Number of wells drilled annually for different uses in the Humboldt River Basin above 

Rye Patch Reservoir, 1950–99. Data are from drillers’ logs submitted to the Nevada Division of Water 

Resources, State Engineer’s Office, Carson City, Nevada.

0

YEAR

200

400

600

800

19491954195919641969197419791984198919941999

E Monitoring, test, and other wells 

0

0

0

200

400

600

800

D Domestic wells 

50

100

150

200

C Municipal and industrial wells 

50

100

150

200

B Irrigation wells 

0

50

100

150

200

NUMBER OF WELLS 

A Stock watering wells 

12 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
Industrial Use

Power Generation

Ground-water withdrawals for power generation have 

been used for cooling at the Valmy Power Plant since 1977 

and for withdrawal of geothermal fluids for the Beowawe 

Geothermal Power Plant since at least 1988. Estimates of 

ground-water withdrawals for power generation ranged from 

about 2,000 acre-ft/yr in 1977 to about 12,000 acre-ft/yr in 

1994 (fig. 8). Between 1997 and 1999, about 77 percent of the 

ground water used for cooling at the Valmy plant came from 

excess water from the nearby Lone Tree Mine (value from 

NDWR files).

Mining Use

Ground water was pumped for mining use more or less 

continuously throughout much of the 1900’s. However, this 

use was minor (less than 1,000 acre-ft/yr) compared with other 

for wells serving irrigated fields. The NDWR crop inventories for 1998 were compared with estimates of ground-water 

withdrawals reported by Plume (2003). Irrigated acreages 

were converted to ground-water withdrawals on the basis 

of the following crop requirements: (1) alfalfa, pasture, and 

potatoes—3 ft/yr, and (2) grains—1.5 ft/yr. Some alfalfa and 

pasture fields were irrigated with surface water when available and ground water was applied only when surface water 

was not available. The quantity of supplemental ground water 

was assumed to be 1 ft/yr. Little or no ground water may be 

pumped at these types of fields during years of well aboveaverage runoff, whereas ground water would have served all 

irrigation needs in years of well below-average runoff. Estimated ground-water withdrawals for irrigation increased from 

a few thousand acre-feet in 1950 to a maximum of about 

160,000 acre-ft in 1981 (fig. 8). Estimated ground-water 

withdrawals for irrigation during 1983–99 ranged from about 

100,000 to 130,000 acre-ft/yr.

Figure 8. Estimates of annual ground-water withdrawals in the Humboldt River Basin above Rye Patch Reservoir, 

1950–99.

WATER YEAR

0

100

200

300

400

500

19501955196019651970197519801985199019952000

GROUND-WATER WITHDRAWALS, IN THOUSANDS OF ACRE-FEET PER YEAR

Mean annual discharge of Humboldt River at Palisade, 1950–99

Power Generation

Mine

Irrigation

Municipal and rural domestic

History of Water Resources Development 13
uses prior to 1990. Mining companies, by the 1980’s, recognized the significance of large, low-grade gold deposits in 

Nevada. Water use for exploiting these gold deposits increased 

rapidly from about 2,000 acre-ft in 1988 to 28,000 acre-ft in 

1990 (fig. 8). This water was used mostly for milling purposes 

and dust control. By 1992, however, ground-water withdrawals 

increased dramatically because of the need to dewater some of 

the mines. As a result, ground-water withdrawals increased to 

more than 120,000 acre-ft in 1992. Ground-water withdrawals 

for mining use peaked at about 261,000 acre-ft in 1998 

(fig. 8).

Some of the water pumped for mine dewatering after 

1991 was discharged to the Humboldt River or to its tributary 

Maggie Creek (fig. 5). Peak discharge from mine dewatering 

was in 1998, the same year that ground-water withdrawals for 

mining use was greatest. In that year, withdrawals for mine 

dewatering and mine consumptive use accounted for about 78 

percent of total ground-water withdrawals in the middle part of 

the Humboldt River Basin (the drainage area between Palisade 

and Comus; Plume, 2003, p. 12) and about 62 percent of the 

total ground-water withdrawals above Rye Patch Reservoir. Of 

the total volume pumped in the middle part of the Humboldt 

River Basin for dewatering, 46 percent (96,700 acre-ft) was 

discharged to the river or to Maggie Creek, 36 percent (74,500 

acre-ft) was returned to local aquifers by infiltration or reinjection, 16 percent (33,100 acre-ft) was substituted for other 

uses (mostly irrigation), and 2 percent (5,260 acre-ft) was lost 

to evaporation (Plume, 2003, p. 12).

Streamflow

The analysis of streamflow conditions and trends on the 

Humboldt River presented herein is based on the records for 

eight streamflow gages, five on the river and one on each of 

three tributaries, and records from 36 weather stations (fig. 2). 

The eight streamflow gages have differing periods of record, 

but all have been in operation since 1945. The 36 weather 

stations also have varying periods of record, and several have 

been in operation since before 1950. The 50-yr period of 

record from water year 1950 to 1999 was selected for analysis of streamflow conditions and trends because streamflow 

records were continuous for the 8 streamflow gages. This 

50-yr period was further subdivided into three shorter periods 

on the basis of changes in ground-water withdrawals (fig. 

8). The three periods reflect differing stages of ground-water 

development in the Humboldt River Basin. The first period, 

1950–70, was one during which ground-water withdrawals 

increased from less than 10,000 acre-ft/yr to 60,000 acre-ft/yr. 

The second period, 1971–91, was one during which groundwater withdrawals increased to about 180,000 acre-ft in 1981 

and thereafter ranged from 130,000 to 180,000 acre-ft/yr until 

1992. The third period, 1992–99, was one during which irrigation withdrawals remained nearly constant, but total groundwater withdrawals increased to more than 420,000 acre-ft 

in 1998 as a result of mining operations. Tables 1 and 2 list 

names, periods of record, and other pertinent information for 

streamflow gages and weather stations, respectively, used for 

this study.

Trends in streamflow correlate not only with the activities of man but also with climate variations. Although the 

influence of man’s activities on streamflow may seem straightforward, the relation is complicated by the effects of climate 

variation. Thus, the effects of man’s activities on streamflow 

cannot be completely understood unless the effects of climate variability also are understood. Streamflow response to 

climate change is difficult to assess because the timing and 

magnitude of response is highly variable. Ideally, the relation 

between climate and streamflow at a particular time scale can 

be defined by comparing streamflow and precipitation records. 

However, many processes, in addition to annual precipitation, affect streamflow, the most important being variations in 

ground-water storage and the interaction between streamflow 

and ground water. Anything that affects ground-water storage indirectly affects runoff and baseflow, and many coupled 

processes influence ground water, including effects caused by 

the natural variability in climate, man’s activities, and flow 

and storage in the unsaturated zone.

Streamflow conditions and trends on the Humboldt River 

and on Lamoille, Rock, and Martin Creeks were analyzed 

using graphical and statistical techniques. The first technique 

involved plotting streamflow data for each streamflow gage 

as time series graphs. The streamflow data presented on these 

graphs are shown as (1) percent departure of annual runoff from the 50-yr mean annual runoff (figs. 9 and 13); (2) 

cumulative annual runoff where the value for any year is the 

sum of all annual runoff up to and including the year for the 

period being evaluated (figs. 10 and 14); (3) mean monthly 

discharges (figs. 11 and 17) and mean daily discharges (fig. 

19); (4) flow duration in which the percentage of time when 

discharge of any magnitude was equaled or exceeded (figs. 

12 and 18); and (5) the difference in cumulative annual runoff 

among stations on the Humboldt River (figs. 15 and 16). 

When data for two or more streamflow gages or for different 

time periods are shown on the same graph, differences in flow 

among the streamflow gages and different time periods and the 

reasons for changes in flow can be evaluated.

Statistical techniques were used to analyze the relation 

of annual runoff to precipitation. Regression models (Helsel 

and Hirsch, 1992) were used to evaluate the relation of mean 

annual precipitation to land-surface altitude and the relation of 

annual runoff to an effective precipitation volume. An effective precipitation volume that included a percent of precipitation from the two previous years was determined by minimizing the square of the difference in rank between annual runoff 

and annual precipitation volume (Searcy and Hardison, 1960).

Multiple linear regression models (Helsel and Hirsch, 1992) 

were used to test for the significance of the effective precipitation volume and ground-water withdrawals on annual runoff at 

streamflow gages along the Humboldt River.

14 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
Tributaries

A number of tributary streams contribute flow to the 

Humboldt River, especially in the upper part of the basin. 

Lamoille Creek was chosen as the tributary to analyze in this 

part of the basin because it has a long period of record 

(table 1) and it is not affected by diversions or impoundments 

above the streamflow gage. Altitude in Lamoille Creek drainage ranges from 6,240 ft at the streamflow gage to more than 

11,000 ft along the crest of the Ruby Mountains. The drainage 

area above the streamflow gage is about 25 mi2.

Martin Creek also was used for the analysis of tributary 

flow for the same reasons as Lamoille Creek. Martin Creek is 

a tributary of the Little Humboldt River (fig. 1), which contributed flow to the Humboldt River in years of well above average runoff and only when a channel was excavated through 

sand dunes that block the natural channel at the south end of 

Paradise Valley (Prudic and Herman, 1996). Altitude in the 

Table 2. Weather stations where precipitation was measured between 1950 and 1999 in the Humboldt River Basin above Imlay, 

Nevada

[Abbreviations: NDWR, Nevada Division of Water Resources; NRCS, U.S. Dept. of Agriculture, Natural Resources Conservation Service (SNOTEL site); 

NCDC, National Oceanic and Atmospheric Administration, National Climate Data Center. Station number is shown in figure 2. Regions are shown in figure 21]

Station 

number Station Name Agency Latitude (degrees minutes)

Longitude 

(degrees minutes)

Altitude 

(feet)

Period of 

Record Region

1 Adobe Summit NDWR 4054 11552 6,550 1960–99 3

2 Angel Lake NDWR 4103 11506 8,380 1959–99 2

3 Antelope Valley Farr NCDC 3958 11726 4,900 1985–97 6

4 Arthur 4NW NCDC 4047 11511 6,300 1949–99 2

5 Austin NCDC 3930 11704 6,605 1950–99 5,6

6 Battle Mountain NCDC 4037 11653 4,540 1950–99 3,7

7 Beaver Creek NDWR 4127 11541 6,263 1966–99 2

8 Beowawe NCDC 4035 11628 4,700 1950–99 3

9 Big Creek Sum NRCS 3918 11707 8,700 1981–99 5

10 Buckskin Lower NDWR 4145 11732 6,700 1981–99 1

11 California Creek NDWR 4124 11554 6,437 1966–99 2

12 Carlin Newmont NCDC 4055 11619 6,520 1968–99 3

13 Corral Canyon NRCS 4017 11532 8,497 1980–99 2

14 Draw Creek NRCS 4139 11512 7,198 1985–99 2,3

15 Elko NCDC 4050 11548 5,080 1950–99 2,3

16 Emigrant Pass Hwy Station NCDC 4039 11618 5,760 1955–99 2,3

17 Gibbs Ranch NCDC 4133 11513 6,000 1953–99 2,3

18 Granite Creek NRCS 4139 11734 7,800 1981–99 1

19 Hanks Creek NDWR 4126 11523 6,552 1950–99 2,3

20 Ione Upper Reese River NDWR 3851 11728 6,995 1953–99 4

21 Lamance NRCS 4131 11738 5,997 1981–99 1

22 Lamoille PH NCDC 4041 11528 6,293 1929–71 2

22 Lamoille 3E NCDC 4044 11526 6,306 1973–75 2

22 Lamoille Yost NCDC 4043 11531 5,840 1975–99 2

23 Lamoille3 NRCS 4038 11524 7,700 1981–99 2

24 Overland Pass #2 NDWR 4001 11535 6,788 1966–99 2

25 Paradise Valley 1NW NCDC 4130 11732 4,675 1955–99 1,3

26 Paris Ranch NCDC 4013 11741 4,140 1967–99 7

27 Pratt NDWR 4129 11556 6,998 1966–99 2

28 Pine Valley Bailey Ranch NCDC 4026 11607 5,047 1957–99 2,3

29 Rattle Snake NDWR 4030 11533 7,198 1966–99 2

30 Reese River O’Toole NCDC 3904 11725 6,550 1973–99 4,5

31 Ruby Lake NCDC 4012 11530 6,010 1949–99 2

32 Saddler Ranch NDWR 4012 11547 5,699 1950–99 2

33 Soldier Creek NDWR 4046 11515 6,998 1950–99 2

34 Tuscarora NCDC 4119 11613 6,170 1958–99 2,3

35 Willow Creek NDWR 4112 11622 5,915 1954–99 3

36 Winnemucca Municipal Airport NCDC 4054 11748 4,297 1950–99 6,7

Streamflow 15
Martin Creek drainage ranges from 4,660 ft at the streamflow 

gage to more than 9,700 ft at the crest of the Santa Rosa 

Range. The drainage area above the streamflow gage is about 

175 mi2. The Martin Creek drainage area differs from that of 

Lamoille Creek in that only 57 percent of the drainage area is 

higher than 6,000 ft (table 3).

The flow of Rock Creek is affected by diversions in its 

upper and lower reaches and by impoundment of streamflow 

on Willow Creek, its main tributary. However, Rock Creek 

contributes flow to the Humboldt River in years of above average runoff (Maurer and others, 1996, p. 27). Altitude in the 

Rock Creek drainage ranges from 4,670 ft at the streamflow 

gage to 8,600 ft at the crest of the Tuscarora Mountains. The 

drainage area above the streamflow gage is 864 mi2; however, 

only 25 percent of the drainage area is higher than 6,000 ft 

(table 3).

The characteristics of runoff from the three tributary 

drainages have some similarities, but they also differ. Mean 

annual runoff at Lamoille Creek during 1950–99 was 33,000 

acre-ft. The geometric mean (mean of the log of annual runoff) was slightly less and the median was slightly more (fig. 

9A). The coefficient of variation was 0.34 and is slightly more 

than that for annual precipitation recorded at the Lamoille 

weather station (fig. 3). The coefficient of variation assuming 

a log-normal distribution was 0.16. Departures from mean 

annual runoff ranged from -55 percent in 1959 to 70 percent in 

1984 and 1997, and were somewhat greater than the maximum 

range in departures from mean annual precipitation of about 

-50 to 50 percent at the Lamoille weather station (fig. 3). The 

number of departures was evenly distributed between those 

above and below mean annual runoff. There were 24 yrs when 

the departure was greater than 5 percent of the mean, 21 yrs 

when the departure was less than -5 percent of the mean, and 6 

yrs when the departure was within 5 percent of the mean.

The mean annual runoff of Martin Creek during 1950–99 

was 28,200 acre-ft, which was less than that of Lamoille Creek 

even though the drainage area of Martin Creek is 7 times 

larger. The geometric mean was less by almost 5,000 acre-ft 

and the median was slightly higher (fig. 9C). The coefficient 

of variation indicates greater variability in annual runoff as 

compared with runoff at Lamoille Creek. Departures from 

mean annual runoff ranged from -73 percent in 1988 to 180 

percent in 1984, again indicating greater variability in annual 

runoff. The number of departures was evenly distributed 

between those above and below mean annual runoff. There 

were 24 yrs when the departure was greater than 5 percent of 

the mean, 23 yrs when the departure was less than -5 percent 

of the mean, and only 3 yrs when the departure was within 5 

percent of the mean.

The mean annual runoff of Rock Creek during 1950-

99 was 31,200 acre-ft (fig. 9B), which was less than that of 

Lamoille Creek even though the drainage area of Rock Creek 

is 35 times larger. The geometric mean was only 17,500 acreft (56 percent of the mean annual runoff) and the median was 

23,200 acre-ft. The much lower geometric mean and median 

annual runoff compared with the mean indicates that the mean 

annual runoff is skewed by a few years of abnormally high 

runoff (1952, 1969, 1983, and 1984). The coefficient of variation indicates greater variability in annual runoff as compared 

with runoff at both Lamoille and Martin Creeks. Departures 

from mean annual runoff ranged from -95 percent in 1994 to 

450 percent in 1984, again indicating greater variability in 

annual runoff.

The number of departures for Rock Creek was not evenly 

distributed between those above and below mean annual 

runoff, unlike Lamoille and Martin Creeks. There were 19 yrs 

when the departure was more than 5 percent of the mean, 

31 yrs when the departure was less than -5 percent of the 

Table 3. Drainage areas and percent of areas below and above 6,000 feet altitude for streamflow gages on Lamoille, Rock, and Martin 

Creeks, and on the Humboldt River near Elko, near Carlin, at Palisade, at Comus, and near Imlay, Nevada

[Locations of streamflow gages are shown in figure 2]

Stream gage

Drainage area in square miles 1 Percent of total2

Total

Below 6,000 feet 

altitude

Above 6,000 feet 

altitude

Below 6,000 feet 

altitude

Above 6,000 feet 

altitude

Tributary streamflow gages

Lamoille Creek 25 0 25 0 100

Rock Creek 864 646 218 75 25

Martin Creek 175 76 99 43 57

Humboldt River streamflow gages

Near Elko 2,780 1,220 1,560 44 56

Near Carlin 4,340 2,090 2,250 48 52

At Palisade 5,050 2,490 2,560 49 51

At Comus 12,200 7,130 5,070 58 42

Near Imlay 15,500 9,850 5,650 64 36

1

 Values are rounded to three significant figures unless drainage area was less than 100 square miles then values were rounded to nearest square mile. 

2

 Percentages were rounded to nearest percent. 

16 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
Figure 9. Departures from mean annual runoff at streamflow gages on A, Lamoille; B, Rock; and C, Martin Creeks, water years 

1950–99. Locations of streamflow gages are shown in figure 2.

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

WATER YEAR

C Martin Creek near Paradise, Nevada 

-100

0

100

200

300

 DEPARTURE FROM MEAN ANNUAL RUNOFF, IN PERCENT

B Rock Creek near Battle Mountain, Nevada 

-100

0

100

200

300

400

500

A Lamoille Creek near Lamoille, Nevada 

Mean annual runoff = 33,000 acre-feet

Coefficient of variation = 0.34

Coefficient of variation assuming log-normal distribution = 0.16

Geometric mean = 31,000 acre-feet

Median annual runoff = 33,900 acre-feet

Mean annual runoff = 31,200 acre-feet

Coefficient of variation = 1.04

Coefficient of variation assuming log-normal distribution = 0.57

Geometric mean = 17,500 acre-feet

Median annual runoff = 23,200 acre-feet

Mean annual runoff = 28,200 acre-feet

Coefficient of variation = 0.60

Coefficient of variation assuming log-normal distribution = 0.28

Geometric mean = 23,500 acre-feet

Median annual runoff = 28,700 acre-feet

-100

0

100

200

Streamflow 17
mean, and no years when the departure was within 5 percent 

of the mean. The large variability in annual runoff at the 

Rock Creek streamflow gage indicates that the area contributing runoff from year to year is not constant, but rather varies 

considerably in relation to the distribution of precipitation, to 

changes in ground-water storage, and perhaps to the operation 

of Willow Creek Reservoir and diversions within the drainage 

above the streamflow gage.

Although Lamoille Creek has the smallest watershed of 

the three tributary streams, it had the largest cumulative runoff 

during 1950–99 (1.65 million acre-ft compared with 1.56 million acre-ft for Rock Creek and 1.41 million acre-ft for Martin 

Creek; fig. 10). Each curve shown in figure 10 is the sum of 

annual runoff since 1950. For example, the value for 1950 is 

the total runoff for that year, whereas the volume for 1980 is 

the sum of all annual runoff from 1950 through 1980. The 

curve for each streamflow gage shows changes in slope that 

relate to wet (more vertical or steeper slopes) and dry (more 

horizontal or flatter slopes) periods.

The variation in annual runoff of Lamoille Creek (figs. 

9 and 10) was much less than either Rock or Martin Creeks. 

This indicates the source of runoff for Lamoille Creek above 

its streamflow gage was from a more consistent annual 

precipitation as suggested by the low coefficient of variation 

for precipitation at the Lamoille weather station (fig. 3), from 

accumulation of a snowpack during years of above average 

precipitation that slowly dissipated during years of below average precipitation, or from shallow ground water stored within 

the near surface alluvial deposits within the canyon floor. Runoff volumes for Rock and Martin Creeks were similar from 

1950 to 1982 even though the drainage area of Rock Creek 

was five times larger than that of Martin Creek. This suggests 

that the proportion of total basin area that contributes runoff to 

Rock Creek in most years was much less than that for Martin 

Creek. The similar patterns of cumulative runoff for Rock and 

Martin Creeks suggest that much of annual variation in Rock 

Creek was related to variation in precipitation.

Total runoff of Rock and Martin Creeks was much larger 

than that of Lamoille Creek in 1983 and 1984 (fig. 9) which 

resulted in a steep increase in cumulative runoff for Rock 

and Martin Creeks relative to the nearly constant slope for 

Lamoille Creek (fig. 10). Well above average precipitation 

during 1983 and 1984 produced large low- and high-altitude 

snowpacks in the drainages of Rock and Martin Creeks, and as 

a result a much larger percentage of the drainage area contributed flow to both streams. Because of its larger drainage 

area, annual flows of Rock Creek greatly exceeded those of 

Lamoille and Martin Creeks in 1983–84 (fig. 10).

Figure 10. Cumulative annual runoff at streamflow gages on Lamoille, Rock, and Martin Creeks, water years 1950–99. 

Locations of streamflow gages are shown in figure 2.

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

WATER YEAR

CUMULATIVE ANNUAL RUNOFF, IN MILLIONS OF ACRE-FEET

Lamoille Creek near Lamoille, Nevada

Rock Creek near Battle Mountain, Nevada

Martin Creek near Paradise Valley, Nevada

18 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
Mean annual discharge of the three tributaries to the 

Humboldt River varied for the three reference periods of 

1950–70, 1971–91, and 1992–99 (fig. 11). Mean annual 

discharge for Lamoille and Martin Creeks was lowest during 

1950-70 and highest during 1992–99, whereas mean annual 

discharge for Rock Creek was highest during 1971–91. The 

lower mean annual runoff during 1950–70 compared with the 

other periods is consistent with lower precipitation during that 

period compared with the later two periods (see fig. 3).

Mean monthly discharge for all three reference periods 

increased from April through July at Lamoille Creek and from 

January through June at Martin Creek, whereas mean monthly 

discharge at Rock Creek differed considerably during 1950–70 

compared with the later two periods (fig. 11). The shorter 

period of high runoff and a later peak in the mean monthly 

discharge at Lamoille Creek compared with that at Martin 

Creek is consistent with the Lamoille Creek drainage having a 

greater percentage of area above 6,000 ft in altitude (table 3).

Lowest mean monthly discharge occurred from December to February at Lamoille Creek, whereas it was in August 

and September in Martin Creek. The lower winter flows at 

Lamoille Creek indicate that most of the drainage area was 

frozen during the winter months, whereas the lower summer 

flows at Martin Creek indicate that at least part of the drainage 

was not frozen during the winter months and that evapotranspiration had a greater relative effect on late summer flows than 

at Lamoille Creek.

Mean monthly discharges at Rock Creek were consistently higher from July to December and were lower from 

February to June during 1950–70 than either during 1971–91 

or during 1992–99 (fig. 11C). The later two periods had a 

pattern of mean monthly discharges that were similar to that 

at Martin Creek although peak discharge occurred in March 

and April instead of May (compare figs. 11B and 11C). The 

abnormal pattern during 1950–70 suggests greater regulation 

of water released from Willow Creek Reservoir, whereas the 

pattern for the later two periods suggests less regulation and 

a more natural distribution of runoff. Earlier peak discharge 

in Rock Creek during the later two periods compared with 

either Martin or Lamoille Creek indicates earlier snowmelt in 

the Rock Creek drainage. Minimum mean monthly discharges 

occurred in July and August and suggest that evapotranspiration in the drainage above the streamflow gage had an important effect on runoff.

Flow-duration curves were used to show differences 

in the character of flow among the tributary streams and to 

show changes in the character of flow for the three reference 

periods (fig. 12). The curves show percentages of time that 

discharge per unit area of a specific magnitude were equaled 

or exceeded. The percentage is plotted as a normal probability, 

which means if the flow durations were normally distributed, 

the curves would plot as a straight line. Discharge per unit 

area, in cubic feet per second per square mile of the drainage 

area, was used because this minimizes the effects of drainage-area size. The flat slopes at the high-flow section of each 

curve (percent of time where indicated discharge per unit area 

Figure 11. Mean monthly discharges at streamflow gages on A, 

Lamoille; B, Rock; and C, Martin Creeks, water years 1950–70, 

1971–91, and 1992–99. Locations of streamflow gages are shown 

in figure 2.

OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT

0

50

100

150

200

250

300

1950–70: Mean annual discharge 35 ft3/s

1971–91: Mean annual discharge 41 ft3/s

1992–99: Mean annual discharge 44 ft3/s

C Martin Creek near Paradise, Nevada

0

50

100

150

200

250

300

MEAN MONTHLY DISCHARGE, IN CUBIC FEET PER SECOND

1950–70: Mean annual discharge 41 ft3/s

1971–91: Mean annual discharge 51 ft3/s

1992–99: Mean annual discharge 46 ft3/s

B Rock Creek near Battle Mountain, Nevada

0

50

100

150

200

250

300

1950–70: Mean annual discharge 42 ft3/s

1971–91: Mean annual discharge 45 ft3/s

1992–99: Mean annual discharge 54 ft3/s

A Lamoille Creek near Lamoille, Nevada

Streamflow 19
Figure 12. Flow duration at streamflow gages on A, Lamoille; B, Rock; and C, Martin Creeks, water years 1950–70, 1971–91, 

and 1992–99. Locations of streamflow gages are shown in figure 2.

1950–70

1971–91

1992–99

A Lamoille Creek near Lamoille, Nevada

DISCHARGE, IN CUBIC FEET PER SECOND PER SQUARE MILE

PERCENT OF TIME INDICATED DISCHARGE

WAS EQUALED OR EXCEEDED

1 2 5 10 20 30 50 70 80 90 95 9899

0.001

100

0.002

0.003

0.005

0.007

0.01

0.02

0.03

0.05

0.07

0.1

0.2

0.3

0.5

0.7

1

2

3

5

7

10

20

30

50

70

B Rock Creek near Battle Mountain, Nevada

C Martin Creek near Paradise Valley, Nevada

DISCHARGE, IN CUBIC FEET PER SECOND PER SQUARE MILE

1 2 5 10 20 30 50 70 80 90 95 98 99

PERCENT OF TIME INDICATED DISCHARGE

WAS EQUALED OR EXCEEDED

0.001

100

0.002

0.003

0.005

0.007

0.01

0.02

0.03

0.05

0.07

0.1

0.2

0.3

0.5

0.7

1

2

3

5

7

10

20

30

50

70

0.00001

1

0.00002

0.00003

0.00005

0.00007

0.0001

0.0002

0.0003

0.0005

0.0007

0.001

0.002

0.003

0.005

0.007

0.01

0.02

0.03

0.05

0.07

0.1

0.2

0.3

0.5

0.7

1950–70

1971–91

1992–99

20 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
was equaled or exceeded was less than 10 percent) for all three 

streams and reference periods are typical of streams dominated 

by snowmelt runoff, or streams with large floodplain storage, 

or those that drain swamps (Searcy, 1959, p. 22). Because 

none of the three tributary streams have large floodplain storage or drain swamps, the likely explanation for the flat slopes 

is snowmelt runoff.

The flat slopes of the low-flow section of the flow-duration curves (percent of time where indicated discharge per 

unit area was equaled or exceeded was more than 90 percent) 

for Lamoille and Martin Creeks are indicative of streams 

with sustained baseflow (flow maintained by water released 

from surface- or ground-water storage). The much steeper 

slope of the low-flow section of the duration curve for Rock 

Creek is indicative of streams with little to no baseflow (flow 

is not maintained by surface- or ground-water storage). The 

differences in low-flow characteristics likely are the result of 

differences in geology of the three drainages. Poorly permeable metamorphic rocks covered with a relatively thin veneer 

of soil, colluvium, alluvium, and glacial deposits underlie 

Lamoille Creek. Volcanic rocks covered with soil, colluvium, 

and alluvium underlie Martin Creek, and relatively thick 

Tertiary sediments underlie much of the Rock Creek drainage. 

The Tertiary sediments that underlie the Rock Creek drainage 

may be more permeable than the rocks beneath Lamoille and 

Martin Creek, and ground-water levels in the deposits beneath 

Lamoille and Martin Creeks probably are close to the stream 

channel as suggested by the flat slopes on the low-flow section 

of the flow-duration curves (fig. 12). Part of the snowmelt in 

the drainages of Lamoille and Martin Creek enters deposits 

beneath the stream channels where it is temporarily stored and 

slowly released during the dry summer and fall months. The 

higher discharge per drainage area for the low-flow section of 

the flow duration curves for Lamoille Creek compared with 

Martin Creek suggests greater storage within the drainage of 

Lamoille Creek (either as ground water or as snowpack) than 

in the Martin Creek drainage. The near vertical slope of the 

low-flow section of the flow duration curve for Rock Creek 

(fig. 12) suggests that the water table is below the level of the 

streambed and water that infiltrates into Tertiary sediments 

beneath Rock Creek likely leaves the drainage as subsurface 

flow. As a result, Rock Creek typically has periods of little or 

no flow during the summer and fall months.

Lamoille and Martin Creeks had higher flow throughout 

most of the flow-duration curve during 1992–99 when compared with the two earlier periods, whereas Rock Creek had 

higher flow throughout most of the flow-duration curve during 

1971–91 (fig. 11). The low-flow section of the flow-duration 

curves for Lamoille and Martin Creeks are nearly the same 

for all three periods indicating that base flow remained nearly 

constant during 1950–99. This suggests that water in storage 

(snowpack, surface impoundments, or ground water) also did 

not change. The low-flow section of the flow-duration curves 

for Rock Creek were higher during 1971–91 and 1992–99 than 

during 1950–70, although little of the low flow was sustained 

by storage as the slopes of the low-flow section of the flowduration curves remained nearly vertical.

Humboldt River

The Humboldt River is a stream of highly variable annual 

runoff. The records of annual runoff at streamflow gages near 

Elko, near Carlin, at Palisade, at Comus, and near Imlay are 

characterized by periods of a few to several years of below 

less than -5 percent and near mean annual runoff (within 5 

percent) separated by less frequent periods of a few years of 

above mean annual runoff (fig. 13). The Humboldt River has 

experienced periods that are three years or more of below 

average runoff in every decade during 1950–99, whereas only 

two periods had three or more years of above average runoff at 

all streamflow gages and they were 1982–84 and 1995–98.

Not only is the Humboldt River one of variable flow, 

but the degree of variation increases downstream (fig. 13). 

Mean annual runoff increased between Elko and Palisade, 

and decreased between Palisade and Imlay. The coefficient 

of variation and the coefficient of variation of the log-normal 

distribution was nearly the same for the streamflow gages near 

Elko, near Carlin, and at Palisade (fig. 13). The coefficient of 

variation for the three streamflow gages was greater than that 

determined for the streamflow gage on Lamoille Creek but 

was similar to that for the streamflow gage on Martin Creek 

(compare figs. 9 and 13). The coefficient of variation increased 

for Comus and Imlay indicating greater variability in annual 

runoff. The coefficient of variation for the streamflow gages 

at Comus and near Imlay was similar to that of the streamflow 

gage on Rock Creek.

Differences in annual runoff and the coefficient of variation indicate major differences in runoff and losses along 

the Humboldt River above and below the streamflow gage at 

Palisade. Annual runoff from the drainage above Palisade was 

dominated by snowmelt runoff from high altitude in headwater 

parts of the basin (Ruby, Jarbidge, and Independence Mountains, and East Humboldt Range) and annual runoff generally 

increased from Elko to Palisade as the drainage area increased 

(Eakin and Lamke, 1966; and table 3). Snowmelt runoff from 

the Tuscarora Mountains, and Santa Rosa and Toiyabe Ranges 

downstream of Palisade during most years was lost to irrigation diversions, to natural evapotranspiration, and to infiltration into alluvium prior to reaching the Humboldt River. 

Annual runoff on the Humboldt River increased from 

Elko to Carlin and from Carlin to Palisade as a result of 

tributary inflow and ground-water discharge to the channel as indicated by greater cumulative annual runoff at the 

Palisade streamflow gage (fig. 14). Annual runoff normally 

decreased at streamflow gages below Palisade as a result of 

irrigation diversions, infiltration of streamflow into alluvium, 

and evapotranspiration. Annual runoff variations among the 

five streamflow gages during 1950–82 were fairly subtle as 

displayed by the changes in the slope of each curve.

Streamflow 21
Figure 13. Departures from mean annual runoff at streamflow gages on Humboldt River A, near Elko; B, near Carlin; C, at Palisade; D,

at Comus; and E, near Imlay, Nevada, water years 1950–99. Locations of streamflow gages are shown in figure 2.

Mean annual runoff = 186,000 acre-feet 

Coefficient of variation = 0.75 

Coefficient of variation assuming log-normal distribution = 0.37

Geometric mean = 139,000 acre-feet 

Median annual runoff = 183,000 acre-feet 

Mean annual runoff = 280,000 acre-feet 

Coefficient of variation = 0.75 

Coefficient of variation assuming log-normal distribution = 0.34

Geometric mean = 217,000 acre-feet 

Median annual runoff = 270,000 acre-feet 

Mean annual runoff = 317,000 acre-feet 

Coefficient of variation = 0.74 

Coefficient of variation assuming log-normal distribution = 0.34

Geometric mean = 246,000 acre-feet 

Median annual runoff = 308,000 acre-feet 

-100

0

100

200

300

400

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

WATER YEAR 

C At Palisade, Nevada 

-100

0

100

200

300

400

 DEPARTURE FROM MEAN ANNUAL RUNOFF, IN PERCENT 

B Near Carlin, Nevada 

-100

0

100

200

300

400 A Near Elko, Nevada 

22 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
Mean annual runoff = 275,000 acre-feet 

Coefficient of variation = 0.95 

Coefficient of variation assuming log-normal distribution = 0.42

Geometric mean = 188,000 acre-feet 

Median annual runoff = 230,000 acre-feet 

Mean annual runoff = 229,000 acre-feet 

Coefficient of variation = 1.06 

Coefficient of variation assuming log-normal distribution = 0.44

Geometric mean = 150,000 acre-feet 

Median annual runoff = 183,000 acre-feet 

-100

0

100

200

300

400

500

600

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

WATER YEAR 

E Near Imlay, Nevada 

-100

0

100

200

300

400

500

600

 DEPARTURE FROM MEAN ANNUAL RUNOFF, IN PERCENT 

D At Comus, Nevada 

Figure 13. Continued.

Streamflow 23
The cumulative annual runoff at all five streamflow gages 

showed a dramatic increase in 1983 and 1984. The abrupt 

increase in slope of each curve represents the highest annual 

runoff recorded on the Humboldt River. Runoff in 1983 and 

1984 was the result of low-altitude snowmelt during late 

winter and early spring of both years followed by a prolonged 

high-altitude snowmelt. Annual runoff at Comus and Imlay 

showed the greatest change during 1983 and 1984 because 

large accumulations of snow over much of the drainage area, 

especially lowland areas (fig. 3), resulted in a much larger part 

of the drainage area that contributed flow to the river.

Relative changes in annual runoff between an upstream 

and downstream gage on the Humboldt River were analyzed 

by plotting differences in cumulative annual flow over time. 

Differences in cumulative annual flow between streamflow 

gages Elko and Carlin, Carlin and Palisade, Palisade and 

Comus, and Comus and Imlay are shown in figure 15. Upward 

sloping curves indicate a gaining reach, whereas downward 

sloping curves indicate a losing reach. The reach of the 

Humboldt River between Elko and Carlin showed the greatest 

gain in annual runoff. This mostly was the result of tributary 

inflow, especially from the South Fork of the Humboldt River. 

The reach of the Humboldt River between Carlin and Palisade 

showed a gain in annual runoff because of tributary flow from 

Maggie, Susie, and Marys Creeks and ground-water discharge. 

The slopes of the cumulative difference curves between Elko 

and Carlin and between Carlin and Palisade, steepened during 1982–84 and during 1994–98 in response to above mean 

annual precipitation.

The Humboldt River below Palisade almost always lost 

flow to irrigation diversions, infiltration of streamflow into 

the alluvium, and evapotranspiration because the cumulative 

difference in annual runoff between Palisade and Comus and 

Comus and Imlay was negative (fig. 15). The greatest annual 

loss was generally between Palisade and Comus, although 

the greatest cumulative loss from 1950 to 1999 was between 

Comus and Imlay because annual runoff at Comus exceeded 

that at Palisade in 1983–84 and again from 1997 to 1999 

(cumulative difference in runoff between Palisade and Comus 

became less negative). Annual runoff along the Humboldt 

River downstream of Palisade was influenced by the effects 

of infrequent accumulation of snow over large areas of lower 

Figure 14. Cumulative annual runoff at selected streamflow gages on Humboldt River, water years 1950–99. Locations of 

streamflow gages are shown in figure 2.

0

2

4

6

8

10

12

14

16

18

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

WATER YEAR 

CUMULATIVE ANNUAL RUNOFF, IN MILLIONS OF ACRE-FEET 

Elko

Carlin

Palisade

Comus

Imlay

24 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
altitudes, whereby annual runoff can occasionally increase 

downstream of Palisade. Thus, variations in annual runoff 

increased below Palisade because of the combined effects 

of annual runoff above Palisade, infrequent accumulation of 

snow at lower altitudes, and increased ground-water storage 

capacity below Palisade.

The discharge of water to the Humboldt River from the 

Betze Mine by way of the T-S Ranch Reservoir from 1997 to 

1999 and the Lone Tree Mine by way of the Lone Tree cooling 

ponds from 1992 to 1999 also contributed to increased runoff 

at Comus (fig. 5; location of cooling ponds shown in fig. 4), 

which when combined with above mean annual precipitation 

and runoff resulted in greater annual runoff at Comus than at 

Palisade from 1997 to 1999. However, the discharge of water 

from the Lone Tree cooling ponds from 1992 to 1996 was 

insufficient to alter the slope of the cumulative difference in 

annual runoff between Palisade and Comus because the slope 

remained unchanged from 1985 to 1996 (fig. 15).

The annual runoff at the streamflow gage near Imlay 

was less than annual runoff at Comus in 1983 and was about 

the same as that at Comus in 1984 and 1985. Some of the 

loss in 1983 was probably caused by ungaged diversions to 

the Upper and Lower Pitt-Taylor Reservoirs upstream of 

Imlay (a streamflow gage recorded diversions from 1947 

to 1977; Berris and others, 2003, p. XV) and some may 

have been caused by greater infiltration into the alluvium 

during high flow.

The slope of the cumulative difference in annual runoff 

between Comus and Imlay increased downward after 1961 

and then was nearly constant until 1982. The increased 

downward slope suggests that more water was lost along the 

reach from 1962 to 1982 than was lost from 1950 to 1961. The 

reason for the change in slope after 1961 is not known but the 

change cannot be explained by increased diversions to the PittTaylor Reservoirs (diversion is above the Imlay streamflow 

gage; fig. 4) as diversions were recorded during 1947; 1951–

53; 1958; 1965–66; and 1969–75 but not during 1961–64. 

Another possibility for the change in slope after 1961 is that 

alluvial aquifers along the Humboldt River floodplain between 

Comus and Imlay slowly released ground water that had been 

Figure 15. Differences in cumulative annual runoff between selected streamflow gages on Humboldt River, water 

years 1950–99. Locations of streamflow gages are shown in figure 2.

-3

-2

-1

0

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

WATER YEAR 

1

2

3

4

5

DIFFERENCE IN CUMULATIVE ANNUAL RUNOFF BETWEEN 

STREAMFLOW GAGES, IN MILLIONS OF ACRE-FEET 

1982 1984 1992

Elko and Carlin 

Carlin and Palisade 

Palisade and Comus 

Comus and Imlay 

1997

Streamflow 25
stored during a period of above mean annual precipitation 

from the late 1930’s into the 1940’s (Eakin and Lamke, 1966, 

p. 19). A similar trend was observed following the wet years 

of 1982–84, in which the slope from 1985–95 was about the 

same as that from 1950–61 and the slope from 1996–1999 was 

about the same as that from 1962–82.

Differences in cumulative annual flow for the reaches 

between Elko and Carlin and Carlin and Palisade form straight 

lines when plotted against the cumulative annual flow of 

the streamflow gage at Palisade (fig. 16). The straight lines 

indicate that any changes in annual runoff were less than what 

could be discerned from the graph or that any change affected 

annual runoff above Palisade equally. The discharge of water 

from Maggie Creek Reservoir (location shown in fig. 4) into 

Maggie Creek had little effect on the difference in annual runoff between Carlin and Palisade. If there had been an effect, 

the difference in annual runoff between Carlin and Palisade 

would have shown an increased slope after 1994.

The cumulative difference in annual flow between Palisade and Comus and between Comus and Imlay did not form 

straight lines (fig. 16), which indicates that both reaches were 

affected differently than reaches between Elko and Carlin 

and Carlin and Palisade. The slope of the curve for the reach 

between Palisade and Comus increased downward after 1952 

indicating that annual runoff at Comus was less after 1952 

relative to the annual runoff at Palisade. Annual runoff at 

Palisade and Comus in 1952 was about twice the mean annual 

runoff from 1950 to 1999 (fig. 13), and annual runoff in 1952 

followed a period from the late 1930’s into the 1940’s of above 

mean annual precipitation (Eakin and Lamke, 1966, p. 19). 

The general downward slope of the cumulative difference in 

annual runoff between Palisade and Comus reversed during 

Figure 16. Differences in cumulative annual runoff between selected streamflow gages on Humboldt River compared with 

cumulative annual runoff at Palisade, Nevada, water years 1950–99. Locations of streamflow gages are shown in figure 2.

-3

-2

0

2

4

5

0 2 4 6 8 10 12 14 16 18

CUMULATIVE ANNUAL RUNOFF AT PALISADE, IN MILLIONS OF ACRE-FEET 

DIFFERENCE IN CUMULATIVE ANNUAL RUNOFF BETWEEN 

STREAMFLOW GAGES, IN MILLIONS OF ACRE-FEET 

Elko and Carlin 

Carlin and Palisade 

Palisade and Comus 

Comus and Imlay 

1952 1982 1984 1992 1997

3

1

-1

26 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
1983–84 and again during 1997–99, both of which correspond 

to periods of above mean annual precipitation and runoff. The 

slope in the cumulative difference in annual runoff between 

Palisade and Comus when compared with cumulative annual 

runoff at Palisade decreased slightly after 1992 (fig. 16). This 

is different from the slope of the difference in cumulative 

runoff shown in figure 15, and suggests that the discharge 

of water from the Lone Tree Mine by way of the Lone Tree 

cooling ponds from 1992 to 1996 had a small effect on the 

difference in annual runoff between the Palisade and Comus 

streamflow gages that could not be discerned in figure 15. The 

most likely explanation for the reach to switch between losing and gaining is that much of the area along the reach only 

contributes sufficient runoff to the Humboldt River during 

infrequent periods of well above the mean annual precipitation 

(both high and low altitude) that are capable of overcoming 

losses due to diversions for irrigation, evapotranspiration, and 

infiltration into the alluvium. 

The cumulative difference in annual runoff between 

Comus and Imlay also showed variations in its slope (fig. 16). 

However, changes in the slope were more gradual compared 

with the reach between Palisade and Comus, suggesting less 

contribution from tributary streams during periods of above 

mean annual precipitation, diversions to the Pitt-Taylor 

Reservoirs, and a greater capacity for ground-water storage. 

The lack of a reversal in the slope and an extended period of a 

flatter slope in the early 1950’s that followed a period of above 

mean annual precipitation during the late 1930’s into the 

1940’s (Eakin and Lamke, 1966, p. 19) and during 1982–84 

suggests that ground-water storage in this reach may be an 

important factor affecting the shape of the curve.

Mean monthly discharge during 1950–70 was less than 

either of the two later periods (fig. 17). Mean annual discharge 

during 1971–91 was greater than during 1950–70 and during 

1992–99 at all streamflow gages. The monthly distribution of 

runoff was the same for all three reference periods. Lowest 

mean monthly discharge was in September at all streamflow 

gages and highest discharge was in June. The pattern is consistent with snowmelt-dominated runoff in which precipitation 

that accumulated as snow during the winter months in the 

mountains became runoff during the spring and early summer, 

and once most of the accumulated snow had melted, runoff 

declined rapidly during late summer.

The mean monthly discharge during 1992–99 had two 

differences when compared with the two earlier periods. First, 

mean monthly discharge in June and July was highest during 1992–99 at all streamflow gages (fig. 17). The reason for 

increased discharge in June and July during 1992–99 in relation to the two earlier periods is unknown but may be caused 

by releases from the South Fork Reservoir, which began 

operation in 1987. Second, mean monthly discharge from 

August through February was also higher during 1992–99 at 

Comus, and the mean monthly discharge at Comus exceeded 

that at Palisade for the same months (fig. 17). The higher mean 

monthly discharges at Comus during what was historically the 

low-flow months can only be attributed to discharge of water 

to the Humboldt River from the Lone Tree and Betze Mines 

(fig. 5).

Flow duration for the three reference periods at each 

streamflow gage on the Humboldt River show a decrease in 

the slope of the curves at high discharge (fig. 18; less than 10 

percent of time that discharge was equaled or exceeded) and 

was similar to the tributary streams (fig. 12). The decrease in 

slope of the flow-duration curves during the low-flow sections 

of the curves (greater than 90 percent of time that discharge 

was equaled or exceeded) at Elko, Carlin, and Palisade 

indicates that discharge during low flow prior to and after the 

South Fork Reservoir was likely sustained by tributary inflow 

and ground-water discharge and operations of the South Fork 

Reservoir had little effect on low flow.

The low-flow section of the flow duration curves at the 

Elko, Carlin, and Palisade streamflow gages during 1950–70 

were consistently lower than those during 1971–91 and during 1992–99. The slightly higher discharge per drainage area 

of the low-flow section of the flow-duration curve during 

1992–99 compared with 1971–91 at Palisade may be caused 

by increased tributary flow from Maggie Creek because water 

from Gold Quarry Mine was discharged into Maggie Creek 

from Maggie Creek Reservoir beginning in 1994 (fig. 5).

The much lower discharge per drainage area and the 

greatly increased slope of the low-flow section of the flowduration curves at Comus suggests that the discharge during 

low flow was not maintained by tributary inflow or groundwater discharge. The higher discharge for much of the flowduration curve during 1992–99 when compared with 1971–91 

was likely caused by, or at least affected by, discharge of water 

from the Betze and Lone Tree Mines (fig. 5). However, much 

of the increased discharge at Comus during 1992–99 did not 

reach Imlay because the low-flow section of the flow-duration curve during 1992–99 was less than that during 1950–70 

and 1971–91 (fig. 18). The higher percentage of time that low 

flow occurred during 1992–99 may have been caused by the 

extended drought from 1986 to 1994. The extended drought 

may have caused increased infiltration between Comus and 

Imlay such that much of the water discharged to the Humboldt 

River above Comus was lost prior to reaching the Imlay gage, 

particularly during 1992–94.

The mean daily discharge for the three reference periods shows a detailed pattern of runoff at each of the five 

streamflow gages on the Humboldt River (fig. 19). Mean daily 

discharges were computed from the daily mean discharges 

for each day of the year during each reference period. The 

general pattern of higher discharge from March through July 

and lower discharge from August through February is the 

same as the distribution of mean monthly discharge (fig. 17). 

Two distinct periods of increased discharge are shown in the 

mean daily discharge during 1950–70 and 1992–99 that is not 

discernable with the mean monthly discharge. The two peaks 

suggest an earlier low-altitude snowmelt followed by a later 

high-altitude snowmelt. An initial peak discharge occurred in 

early April at Elko and late April at Carlin and Palisade

Streamflow 27
Figure 17. Mean monthly discharges at streamflow gages on Humboldt River A, near Elko; B, near Carlin; C, at Palisade; D, 

at Comus; and E, near Imlay, Nevada, water years 1950–70, 1971–91, and 1992–99. Locations of streamflow gages are shown in 

figure 2.

1950–70: Mean annual discharge 206 ft3/s

1971–91: Mean annual discharge 302 ft3/s

1992–99: Mean annual discharge 275 ft3/s

1950–70: Mean annual discharge 308 ft3/s

1971–91: Mean annual discharge 455 ft3/s

1992–99: Mean annual discharge 416 ft3/s

1950–70: Mean annual discharge 349 ft3/s

1971–91: Mean annual discharge 515 ft3/s

1992–99: Mean annual discharge 475 ft3/s

1950–70: Mean annual discharge 262 ft3/s

1971–91: Mean annual discharge 466 ft3/s

1992–99: Mean annual discharge 459 ft3/s

1950–70: Mean annual discharge 216 ft3/s

1971–91: Mean annual discharge 394 ft3/s

1992–99: Mean annual discharge 372 ft3/s

0

500

1,000

1,500

2,000

E Near Imlay, Nevada

D At Comus, Nevada

0

500

1,000

1,500

2,000

C At Palisade, Nevada

0

500

1,000

1,500

2,000

MEAN MONTHLY DISCHARGE, IN CUBIC FEET PER SECOND

B Near Carlin, Nevada

0

500

1,000

1,500

2,000

A Near Elko, Nevada 

0

500

1,000

1,500

2,000

OCT NOV DEC JAN FEB MAR APR MAYJUNE JULYAUG SEPT

OCT NOV DEC JAN FEB MAR APR MAYJUNE JULYAUG SEPT

28 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
Figure 18. Flow duration at streamflow gages on Humboldt River A, near Elko; B, near Carlin; C, at Palisade; D, at Comus; and 

E, near Imlay, Nevada, water years 1950–70, 1971–91, and 1992–99. Locations of streamflow gages are shown in figure 2.

1950–70

1971–91

1992–99

0.00001

1

0.00002

0.00005

0.0001

0.0002

0.0005

0.001

0.002

0.005

0.01

0.02

0.05

0.1

0.2

0.5

PERCENT OF TIME INDICATED DISCHARGE WAS EQUALED OR EXCEEDED

1 2 5 10 20 30 50 70 80 90 95 98 99 1 2 5 10 20 30 50 70 80 90 95 98 99 1 2 5 10 20 30 50 70 80 90 95 98 99

0.00001

1

0.00002

0.00005

0.0001

0.0002

0.0005

0.001

0.002

0.005

0.01

0.02

0.05

0.1

0.2

0.5

A Near Elko, Nevada B Near Carlin, Nevada C At Palisade, Nevada

1 2 5 10 20 30 50 70 80 90 95 98 99 1 2 5 10 20 30 50 70 80 90 95 98 99

0.00001

1

0.00002

0.00005

0.0001

0.0002

0.0005

0.001

0.002

0.005

0.01

0.02

0.05

0.1

0.2

0.5

DISCHARGE, IN CUBIC FEET PER SECOND PER SQUARE MILE

D At Comus, Nevada E Near Imlay, Nevada

0.00001

1

0.00002

0.00005

0.0001

0.0002

0.0005

0.001

0.002

0.005

0.01

0.02

0.05

0.1

0.2

0.5

Streamflow 29
during 1950–70 whereas a second and larger peak occurred 

in early June. The initial peak discharge at Comus and Imlay 

during 1950–70 occurred in late April and early May and was 

higher than the later second peak in late June and early July 

(fig. 19).

The initial peak discharge during 1992–99 was earlier at 

all five streamflow gages with the initial peak occurring in late 

March at Elko, Carlin, and Palisade and late March to early 

April at Comus and Imlay. However, the discharge for the 

initial peak at Comus and Imlay was less than the later peak 

in June and July, which differs from the two earlier reference 

periods. This suggests a changing pattern in the low-altitude 

snowmelt that results in an earlier but diminished runoff, 

particularly at Comus and Imlay. Two earlier peaks during 1971–91 generally correspond to the initial peaks during 

1950–70 and 1992–99 suggesting that the middle reference 

period includes the transition from a later to earlier low-altitude snowmelt.

The dramatic increase in peak flow between Elko and 

Carlin for all reference periods was caused by tributary inflow 

from the South Fork of the Humboldt River, which drains 

much of the western Ruby Mountains (fig. 1). The dramatic 

decrease in peak flow between Palisade and Comus indicates 

considerable loss between the two streamflow gages as a result 

of diversions and from infiltration into the alluvium.

Differences in mean daily discharge for the three reference periods during low flow are not readily discernable in 

figure 19 and consequently the period from September 1 to 

December 30 is shown for the five streamflow gages in figure 

20. The mean daily discharge from September 1 to December 30 during 1950–70 increased from Elko to Carlin and 

from Carlin to Palisade, whereas the mean daily discharge 

Figure 19. Mean daily discharge at streamflow gages on 

Humboldt River A, near Elko; B, near Carlin; C, at Palisade; D, 

at Comus; and E, near Imlay, Nevada, water years 1950–70, 

1971–91, and 1992–99. Locations of streamflow gages are shown 

in figure 2.

B Near Carlin, Nevada

0

500

1,000

1,500

2,000

2,500

3,000

O N D J F M A M J J A S

MONTH

MEAN DAILY DISCHARGE, IN CUBIC FEET PER SECOND

A Near Elko, Nevada

0

500

1,000

1,500

2,000

2,500

3,000

1950–70

1971–91

1992–99

E Near Imlay, Nevada

0

500

1,000

1,500

2,000

2,500

3,000

O N D J F M A M J J A S

MONTH

D At Comus, Nevada

0

500

1,000

1,500

2,000

2,500

3,000

MEAN DAILY DISCHARGE, IN CUBIC FEET PER SECOND

C At Palisade, Nevada

0

500

1,000

1,500

2,000

2,500

3,000

1950–70

1971–91

1992–99

30 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
Mean daily flow from September 1 through December 30 

during 1971–91 was consistently greater than during 1950–70 

and resulted from greater precipitation. Although mean daily 

discharge was greater, the overall pattern of increased discharge from Elko to Carlin and Carlin to Palisade, decreased 

discharge from Palisade to Comus, and increased discharge 

from Comus to Imlay was the same as during 1950–70 

(fig. 20).

The pattern changed from Palisade to Comus and Comus 

to Imlay during 1992–99 when mean daily discharge was 

greater at Comus than either Palisade or Imlay. Additionally, 

mean daily discharge during 1992–99 was less than that during 

1971–91 at Elko and Carlin and most of the time at Palisade, 

whereas the mean daily discharge was mostly greater than that 

during 1971–91 at Comus and about the same at Imlay. The 

marked increase in mean daily discharge during 1992–99 at 

Comus with respect to the mean daily discharge at Palisade 

was caused by the discharge of water from the Betze and Lone 

Tree Mines. The decrease in mean daily discharge between 

Comus and Imlay indicates that part of the water discharged 

to the Humboldt River either was diverted or infiltrated into 

alluvium prior to reaching the streamflow gage near Imlay.

Annual Precipitation Volume

Annual precipitation volume in the drainage area above 

a streamflow gage is difficult to estimate because it requires 

integrating annual precipitation measured at a few locations over the entire drainage area, which is different than a 

streamflow gage that normally represents all runoff from the 

drainage area above the gage. The uncertainty in estimates 

of annual precipitation volume depends on how well the few 

measured locations of precipitation represent the distribution 

precipitation over the entire drainage area.

Method Used

The method devised to estimate precipitation volumes 

above each streamflow gage was an attempt to account for the 

natural variability in precipitation using the limited number of 

weather stations shown in figure 2 and listed in table 2. The 

natural variability in precipitation results from two principal 

factors. The first factor is how storms generally track across 

the Humboldt River Basin (Houghton and others, 1975). The 

basin upstream of the streamflow gage near Imlay encompasses an area of about 15,500 mi2

 (table 3). The second factor 

is the large differences in altitude among the many mountain 

ranges and adjacent valleys. Because of the way storms generally track across Nevada, mean annual precipitation is more 

at the north and east ends of the Humboldt River Basin (fig. 

21). For example, the Toiyabe Range in the southern part of 

the basin has less mean annual precipitation at similar altitude 

than the Santa Rosa Range and the Independence and Jarbidge 

Mountains to the north. The effect of altitude results in precipitation ranging from about 9 in. in the valley lowland near 

Elko, Nevada to more than 36 in. at the highest altitudes in the 

nearby Ruby Mountains (fig. 21).

Figure 20. Mean daily discharges from September through 

December at streamflow gages on the Humboldt River A, near 

Elko; B, near Carlin; C, at Palisade; D, at Comus; and E, near 

Imlay, Nevada, water years 1950–70, 1971–91, and 1992–99. Mean 

monthly discharges of water to Humboldt River or tributary from 

mining operations included for streamflow gages downstream of 

Carlin. Locations of streamflow gages are shown in figure 2.

E Near Imlay, Nevada

0

40

80

120

160

1950–70

1971–91

1992–99

 Mine discharge

D At Comus, Nevada

0

40

80

120

160

200

1-Sep 21-Sep 11-Oct 31-Oct 20-Nov 10-Dec 30-Dec

MEAN DAILY DISCHARGE, IN CUBIC FEET PER SECOND

C At Palisade, Nevada

0

40

80

120

160

200

B Near Carlin, Nevada

0

40

80

120

160

A Near Elko, Nevada

0

40

80

120

Annual Precipitation Volume 31

decreased markedly from Palisade to Comus, a pattern consistent with mean daily discharge during peak flow (fig. 19). 

However, the mean daily discharge from September 1 until the 

end of December during 1950–70 at Imlay was greater than 

that at Comus. Because little tributary inflow from intermittent streams occurred during late summer and fall, much of 

the increase in low flow along the reach between Comus and 

Imlay likely was from ground-water discharge to the river. 

Increases in ground-water discharge between Comus and 

Imlay during this period were documented by Cohen and others (1965) and Eakin and Lamke (1966).
The mean annual precipitation was used as a basis for 

estimating annual precipitation in the drainage areas above 

each streamflow gage. The distribution of mean annual 

precipitation was developed by Daly and others (1994) 

using mean-annual precipitation data from 1960 to 1991 and 

their propriety computer model named Precipitation-Elevation Regressions on Independent Slopes Model (PRISM). 

Estimates of mean annual precipitation from PRISM were 

provided by G.H. Taylor (Oregon Climate Service, Oregon 

State University, written commun., 1997) for a 2.4 mi2 (2.5 km 

by 2.5 km) grid.

Because the relation between precipitation and altitude 

was not the same throughout the basin, 21 transects were 

drawn across all major mountain ranges and adjacent valleys 

(fig. 21) and precipitation was compared with altitude to determine regions that had similar characteristics. Four transects 

were drawn across the Ruby Mountains and East Humboldt 

Range because the mountains have the greatest mean annual 

precipitation (fig. 2). The mean altitude for each 2.4 mi2 grid 

along transects was determined from 2 acre (90 m by 90 m) 

digital elevation model (DEM) data (1-degree DEM data; U.S. 

Geological Survey, 2000). Mean annual precipitation for each 

PRISM grid along all transects (the dependent variable) was 

plotted against its corresponding altitude (the independent 

variable).

The data were grouped into seven regions on the basis 

of similar distributions between precipitation and altitude 

(fig. 21). For example, regions 3 and 7 were divided along the 

Humboldt River between Winnemucca and the streamflow 

gage at Palisade because there was more precipitation in 

region 3 at a similar altitude than in region 7. Region 2 was 

used to relate precipitation and altitude for the Ruby Mountains, East Humboldt Range, Jarbidge Mountains, and the 

highest part of the Independence Mountains, whereas three 

regions (regions 4, 5, and 6) were used for the Toiyabe Range 

in the southernmost part of the basin. The seven regions 

sufficiently captured the variation in mean annual precipitation from north to south and from west to east. The different 

regions also allowed for annual variations in precipitation 

across the basin to be incorporated into the estimates of annual 

precipitation volumes. 

Equations that relate mean annual precipitation from the 

PRISM data to a corresponding altitude were calculated for 

each region using several types of regression equations (linear, 

natural log, power, and polynomial). The regression equation 

used for each region was chosen by comparing residuals to 

predicted precipitation (Helsel and Hirsch, 1992) and from the 

coefficient of determination or R2 (fig. 22). Equations for areas 

with higher precipitation in the mountain regions (regions 1 

and 2) were represented by a natural log equation, whereas the 

other regions were represented by a linear equation (regions 

3 and 6), an exponential function (region 4), or by a second 

order polynomial (regions 5 and 7).

Annual precipitation was estimated by adjusting the 

regression equations that relate mean annual precipitation to 

altitude for each of the 7 regions (fig. 22). Each regression 

equation was adjusted for each water year by fitting the equation (without changing its shape) to best fit precipitation that 

had been recorded at all active precipitation stations in each 

region. Thus, a value dependent on annual precipitation at 

precipitation stations was added to the regression equation of 

each region for years where precipitation was greater than the 

mean and a value was subtracted from the regression equation 

for years where precipitation was less than the mean. 

Precipitation recorded at all active stations for a water 

year was determined from monthly precipitation totals for all 

precipitation stations except for the high-altitude bulk-storage 

gages operated by NDWR. The bulk-storage gages typically 

were measured in April and October of each year. Not all 

precipitation stations were operational during the entire period 

(table 2). Many of the high-altitude bulk-storage gages operated by NDWR began in water year 1953. Because there was 

little information on high-altitude precipitation prior to water 

year 1953, precipitation volumes for water years 1950–52 

were not estimated. Also, many of the high-altitude SNOTEL 

stations operated by the NRCS of the U.S. Department of 

Agriculture began during water year 1981 (table 2); consequently, estimates of annual precipitation volume for water 

years prior to 1981 were limited mostly to the high-altitude 

bulk-storage gages operated by NDWR. Annual water-year 

adjustments that were either added to (for above mean annual 

precipitation) or subtracted from (for below mean annual precipitation) each regression equation for water years 1953–99 

are listed in table 4.

Annual precipitation volume for each region above the 

three tributary and five Humboldt River streamflow gages 

was estimated by multiplying the annual precipitation estimated from the regression equations with an area of a selected 

altitude range in each region. The area in acres for an altitude 

interval of 1,000 ft was determined for each region starting at 

a base altitude of 4,000 ft (table 5). An average precipitation 

across the selected altitude ranges for each water year was 

determined from the adjusted regression equation. The annual 

precipitation volume in each region was estimated by summing over all altitude intervals.

Annual precipitation volume above each streamflow 

gage was estimated by summing precipitation volumes in each 

region within the drainage area above the gage for water years 

1953–99 (table 6). The lack of measured precipitation in many 

parts of the Humboldt River Basin does not justify a more 

sophisticated approach in estimating precipitation volumes. 

The method used provides an estimate of annual precipitation 

volumes that is consistent with measured precipitation in the 

basin. Although the absolute volumes may be more or less 

than what actually occurred in the basin, a more sophisticated 

approach would suffer from the same lack of data. A more 

sophisticated approach could perhaps provide for a better 

estimate of method uncertainty.

32 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
Figure 21. Distribution of mean annual precipitation and transects used to determine regions of different mean annual precipitation 

with respect to land-surface altitude. Mean annual precipitation was estimated for 1960–91 by Daly and others (1994) for all of 

Nevada. Estimates of mean annual precipitation for a 2.4 square mile grid were provided by G.H. Taylor (Oregon Climate Service, 

Oregon State University, written commun., 1997).

Base from U.S. Geological Survey digital data 1:100,000, 1977-1988

Universal Transverse Mercator projection, Zone 11, NAD 27

3

7

2

4

1

5

2

6

2

6

5

3

7

2

4

1

5

2

6

2

6

5

0 20 40 60 MILES

0 20 40 60 KILOMETERS

39°

40°

41°

119°

118°

117°

116°

115°

EXPLANATION

Transect

Precipitation region boundary and number

3

Precipitation, in inches

36 – 44

29 – 36

21 – 28

13 – 20

 6 – 12

Jarbidge

Mountains

Independence

Santa Rosa Range

Tuscarora

Mountains

East

Humboldt

Range

Toiya

be

Range

Mountains

Ruby

Mountains

Annual Precipitation Volume 33
Figure 22. Relation of mean annual precipitation to land-surface altitude by region in the Humboldt 

River Basin. Locations of regions are shown in figure 21.













   

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Y
E 
X

2













   

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Y
X




















   

02%#)0)4!4)/.).).#(%3

Y
,NX	


2 

2 





















   

Y
,NX	


2

!2EGION

"2EGION

#2EGION

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34 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
%2EGION

&2EGION

'2EGION

















   

!,4)45$%).&%%4!"/6%3%!,%6%,

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02%#)0)4!4)/.).).#(%3

    

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X


Annual Precipitation Volume 35

Figure 22. Continued.
Table 4. Annual adjustments to the regression equations of mean annual precipitation and land-surface altitude by region in the 

Humboldt River Basin, north-central Nevada for water years 1953–99

[All values are in inches. Locations of regions are shown in figure 21]

Year

Region

1 2 3 4 5 6 7 Below 6,000 feet Above 6,000 feet

1953 -6.79 -2.21 -4.40 -6.82 -3.61 -7.85 -5.98 -4.67

1954 -6.48 -2.82 -2.41 -6.83 -2.96 -3.25 -4.76 -4.22

1955 -6.08 -2.71 -3.59 -6.84 1.88 -3.19 -4.58 -4.65

1956 -0.99 1.66 1.00 -3.56 8.77 1.04 0.08 -4.65

1957 -2.33 2.07 -0.32 -3.33 4.18 -4.49 -4.72 -1.30

1958 2.21 1.64 -1.48 -3.53 3.98 0.38 0.62 -0.09

1959 -5.15 -2.26 -3.62 -4.49 -0.17 -7.95 -6.32 -4.56

1960 -4.76 -0.30 -4.80 -4.22 0.08 -6.25 -5.57 -4.23

1961 -4.34 -0.95 -2.84 -7.06 9.68 -3.20 -2.23 -1.95

1962 -4.40 1.06 -0.29 -2.33 7.73 -4.11 -2.80 -0.07

1963 -4.10 3.60 0.73 0.33 1.18 1.30 0.53 0.29

1964 -4.59 1.24 0.71 -5.23 4.33 1.68 0.72 0.72

1965 -2.58 4.22 4.52 1.36 3.38 7.18 3.60 1.69

1966 -7.85 -4.53 -2.85 -6.64 0.43 -5.08 -6.20 -4.38

1967 -1.49 0.87 0.69 -4.21 6.13 -1.15 -0.91 -1.44

1968 -4.82 -0.91 0.31 -3.29 6.23 -3.94 -5.17 -2.56

1969 -0.43 3.07 0.56 -0.17 7.28 2.43 1.43 0.46

1970 1.41 3.10 2.23 -0.39 4.53 0.87 0.60 0.30

1971 -1.15 4.59 2.25 -1.87 3.63 3.72 0.77 -1.47

1972 -4.40 0.84 -1.55 -4.36 -0.27 -0.02 -2.62 -3.66

1973 -1.24 -0.15 1.94 -3.18 3.99 3.98 1.59 0.32

1974 -4.28 -0.90 -2.30 -6.24 -3.46 -3.52 -4.06 -2.48

1975 -1.18 1.14 3.12 -2.91 5.55 8.13 3.23 0.65

1976 -2.53 -0.34 1.54 -5.09 3.38 3.24 0.73 0.49

1977 -4.53 -2.53 -3.60 -4.83 3.17 -2.23 -2.92 -2.94

1978 -0.06 2.33 2.92 2.05 3.81 6.13 2.37 2.57

1979 -4.21 0.09 -0.44 -2.09 3.08 0.35 -1.30 0.03

1980 1.33 4.84 1.34 1.25 4.92 -0.16 -1.80 0.56

1981 -6.19 -2.28 -3.04 -6.79 0.09 -2.44 -3.70 -2.79

1982 11.20 4.33 1.90 2.34 1.60 2.58 1.24 0.13

1983 8.00 6.57 3.28 0.21 6.06 5.04 3.52 2.67

1984 12.30 10.68 3.97 3.85 6.38 12.43 6.26 3.46

1985 -2.82 0.97 -1.15 -3.03 5.02 0.84 -1.47 -1.59

1986 3.80 1.08 0.18 -1.49 1.37 -1.85 -1.83 -1.00

1987 -4.35 -1.06 -1.75 -5.02 3.83 0.28 -1.68 -0.47

1988 -7.82 -3.85 -0.68 -5.43 3.90 3.94 -1.82 -1.01

1989 5.64 -1.76 -2.10 -2.15 2.06 1.45 -2.23 -0.73

1990 -6.49 -1.62 -0.17 -5.86 1.53 -0.13 -1.99 -0.86

1991 -2.30 -1.98 -0.92 -4.82 1.35 0.65 -1.93 -1.74

1992 -9.65 -2.74 -2.23 -4.89 0.79 -3.00 -4.38 -2.72

1993 6.14 2.56 2.14 -0.20 0.42 -2.45 -3.08 0.20

1994 -8.45 -1.26 -0.35 -6.93 -0.99 -1.83 -3.69 -2.30

1995 7.63 4.15 4.58 1.84 5.47 3.38 1.52 0.81

1996 1.68 3.52 0.86 -2.69 0.39 1.28 -2.12 -0.44

1997 3.71 10.14 2.57 -0.15 3.60 -3.15 0.05 2.37

1998 8.00 4.37 5.41 -0.27 5.64 8.37 5.97 6.29

1999 -1.87 3.74 -0.08 -3.31 2.79 -3.99 -3.58 -0.94

36 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
Table 5. Areas of land-surface altitude intervals used to estimate precipitation volumes in drainage areas above selected streamflow 

gages on Lamoille, Rock, and Martin Creeks, and on Humboldt River, north-central Nevada

[All areas are in acres. Symbol: --, interval does not exist. Locations of streamflow gages and regions are shown in figures 2 and 21, respectively]

Region

Land-surface altitude interval, in feet above sea level

Total Area

4,000-

4,999

5,000-

5,999

6,000-

6,999

7,000-

7,999

8,000-

8,999

9,000-

9,999

10,000-

10,999 >11,000

Lamoille Creek

2 -- -- 612 2,461 4,281 5,878 2,651 56 15,938

Rock Creek

3 36,339 376,711 119,654 17,964 2,130 -- -- -- 552,798

Martin Creek

1 1,555 47,128 45,764 15,545 2,107 57 -- -- 112,157

Humboldt River near Elko

2 -- 252 206,130 86,240 50,553 30,156 8,623 185 382,139

3 -- 782,288 532,017 75,300 6,855 -- -- -- 1,396,460

Combined -- 782,540 738,147 161,540 57,408 30,156 8,623 185 1,778,599

Humboldt River near Carlin

2 -- 263 320,568 143,344 85,796 54,508 16,258 215 620,952

3 3,633 1,333,571 710,189 98,973 10,119 13 -- -- 2,156,498

Combined 3,633 1,333,834 1,030,757 242,317 95,915 54,521 16,258 215 2,777,450

Humbold River at Palisade

2 -- 263 320,568 143,344 85,796 54,508 16,258 215 620,952

3 18,511 1,577,938 879,648 125,628 11,628 13 -- -- 2,613,366

Combined 18,511 1,578,201 1,200,216 268,972 97,424 54,521 16,258 215 3,234,318

Humboldt River at Comus

2 -- 263 320,568 143,344 85,796 54,508 16,258 215 620,952

3 507,795 2,266,369 1,133,157 180,738 16,903 13 -- -- 4,104,975

4 -- 216 97,681 94,853 73,229 25,578 6,064 220 297,841

5 -- -- 122,882 52,520 16,459 3,715 390 -- 195,966

6 -- 95 77,143 40,114 7,876 1,655 65 -- 126,948

7 573,098 1,230,076 531,905 125,972 12,810 455 -- -- 2,474,316

Combined 1,080,893 3,497,019 2,283,336 637,541 213,073 85,924 22,777 435 7,820,998

Humboldt River near Imlay

1 1,796 94,258 125,299 36,321 6,719 247 -- -- 264,640

2 -- 263 320,568 143,344 85,796 54,508 16,258 215 620,952

3 1,040,771 2,660,747 1,208,241 194,422 17,549 13 -- -- 5,121,743

4 -- 216 97,681 94,853 73,229 25,578 6,064 220 297,841

5 -- -- 122,882 52,520 16,459 3,715 390 -- 195,966

6 -- 145 115,963 56,791 12,384 1,844 65 -- 187,192

7 1,101,578 1,407,637 581,661 129,938 12,889 455 -- -- 3,234,158

Combined 2,144,145 4,163,266 2,572,295 708,189 225,025 86,360 22,777 435 9,922,492

Annual Precipitation Volume 37
Table 6. Precipitation volumes estimated for water years 1953–99 in drainage areas above selected streamflow gages on Lamoille, 

Rock, and Martin Creeks, and on Humboldt River, north-central Nevada 

[Volumes are in millions of acre-feet. Locations of streamflow gages are shown in figure 2]

Year Lamoille Creek Rock Creek Martin Creek

Humboldt River 

near Elko near Carlin at Palisade at Comus near Imlay

1953 0.041 0.346 0.153 1.611 2.537 2.841 5.388 6.480

1954 0.040 0.414 0.156 1.720 2.726 3.072 6.029 7.295

1955 0.040 0.373 0.160 1.646 2.599 2.919 5.781 6.951

1956 0.046 0.569 0.207 2.253 3.561 4.035 7.759 9.408

1957 0.046 0.527 0.195 2.192 3.451 3.901 7.957 9.646

1958 0.046 0.485 0.237 2.092 3.286 3.707 8.026 9.826

1959 0.041 0.399 0.168 1.778 2.779 3.137 5.931 7.133

1960 0.043 0.362 0.172 1.778 2.768 3.106 5.895 7.048

1961 0.042 0.396 0.176 1.740 2.758 3.092 6.826 8.244

1962 0.045 0.539 0.175 2.213 3.471 3.937 8.402 10.131

1963 0.048 0.605 0.178 2.495 3.896 4.429 9.109 10.971

1964 0.045 0.540 0.174 2.134 3.392 3.833 8.544 10.377

1965 0.049 0.748 0.192 2.815 4.422 5.053 10.646 12.906

1966 0.038 0.401 0.143 1.647 2.602 2.942 5.862 7.053

1967 0.045 0.551 0.203 2.173 3.441 3.897 8.150 9.932

1968 0.042 0.549 0.171 2.139 3.370 3.833 7.741 9.348

1969 0.048 0.594 0.212 2.442 3.816 4.337 9.201 11.143

1970 0.048 0.649 0.230 2.541 3.989 4.542 9.441 11.526

1971 0.050 0.632 0.206 2.513 3.967 4.495 9.003 10.925

1972 0.045 0.473 0.175 2.020 3.180 3.586 6.962 8.394

1973 0.043 0.606 0.205 2.275 3.598 4.098 8.944 10.935

1974 0.042 0.425 0.176 1.819 2.878 3.236 6.585 8.010

1975 0.045 0.650 0.205 2.407 3.815 4.345 9.520 11.623

1976 0.043 0.570 0.193 2.146 3.413 3.874 8.629 10.554

1977 0.040 0.396 0.174 1.754 2.745 3.099 6.447 7.767

1978 0.047 0.701 0.216 2.686 4.192 4.800 10.410 12.661

1979 0.044 0.537 0.177 2.183 3.419 3.886 8.334 10.071

1980 0.050 0.637 0.229 2.621 4.091 4.651 9.521 11.556

1981 0.041 0.393 0.159 1.699 2.687 3.021 6.320 7.632

1982 0.049 0.669 0.321 2.698 4.202 4.792 9.652 11.943

1983 0.052 0.692 0.291 2.750 4.326 4.911 10.582 13.033

1984 0.058 0.758 0.331 3.113 4.865 5.525 11.693 14.371

1985 0.045 0.502 0.190 2.117 3.322 3.758 7.814 9.437

1986 0.045 0.565 0.252 2.286 3.581 4.071 8.296 10.199

1987 0.042 0.458 0.176 1.912 3.014 3.404 7.544 9.137

1988 0.038 0.490 0.143 1.871 2.960 3.367 7.552 9.109

1989 0.041 0.479 0.269 2.014 3.135 3.565 7.656 9.450

1990 0.041 0.502 0.156 1.954 3.103 3.514 7.648 9.274

1991 0.041 0.489 0.195 1.947 3.073 3.485 7.385 9.012

1992 0.040 0.443 0.126 1.834 2.883 3.265 6.717 8.025

1993 0.047 0.648 0.274 2.527 3.964 4.518 9.195 11.355

1994 0.042 0.484 0.137 1.899 3.029 3.418 7.087 8.563

1995 0.049 0.755 0.288 2.841 4.457 5.097 10.486 12.919

1996 0.048 0.575 0.232 2.347 3.701 4.186 8.595 10.519

1997 0.057 0.663 0.251 2.799 4.407 4.971 10.261 12.531

1998 0.049 0.760 0.291 2.795 4.418 5.042 11.776 14.582

1999 0.049 0.535 0.199 2.261 3.565 4.020 8.165 9.907

38 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
Trends

Water-year precipitation volumes varied among the three 

tributary streamflow gages on Lamoille, Rock, and Martin 

Creeks and from year to year as shown by departures from 

mean annual precipitation volumes (fig. 23). The drainage area 

of Lamoille Creek produced the least precipitation volume 

because it has the smallest area (25 mi2 compared with 175 

mi2 for Martin Creek and 864 mi2 for Rock Creek) even 

though it has the highest annual rate (33.9 in. for Lamoille 

Creek compared with 21.7 in. for Martin Creek, and 12 in. 

for Rock Creek). The coefficient of variation for Lamoille 

Creek was much less than that for Rock and Martin Creeks 

(0.10 compared with 0.21 percent for Rock Creek and 0.24 

percent for Martin Creek) suggesting that precipitation in 

the higher elevations of the Ruby Mountains varies less from 

year to year than in drainages that include large areas of lower 

altitude. Although not entirely consistent, the three drainages generally were below mean annual precipitation volume 

during 1953–61 and during 1985–92, and were above the 

mean annual precipitation volume during 1969–71, 1982–84, 

and 1993–98. Water years 1963 and 1965 were above mean 

annual precipitation volume for Lamoille and Rock Creeks but 

below the mean annual precipitation volume for Martin Creek 

suggesting that precipitation was greater towards the east side 

of the Humboldt River Basin during those years. The highest 

annual precipitation volume was in 1984 for both Lamoille 

and Martin Creeks, whereas annual precipitation volumes 

during 1965, 1995, and 1998 nearly equaled 1984 in the Rock 

Creek drainage.

The departures from mean annual precipitation volume for water years 1953–99 in the drainage areas above 

streamflow gages along the Humboldt River near Elko, Carlin, 

and at Palisade showed a greater annual variation than the 

annual precipitation volume for Lamoille Creek but less than 

that for Rock Creek (figs. 23 and 24). The 1950’s generally 

had less annual precipitation volume than during 1985–92. 

Highest annual precipitation was in 1984 and the lowest was 

in 1953. The coefficient of variation was nearly the same for 

all three drainage areas (0.17 to 0.18).

The mean annual precipitation volume in the drainage 

area above Comus (8.2 million acre-ft) was about double the 

mean annual precipitation volume above the Palisade gage 

(3.9 million acre-ft), and the increase in the corresponding 

drainage areas was about 2.5 times. The mean annual precipitation in the drainage areas above Palisade and Comus for 

water years 1953–99 was about 14.6 in. and 12.3 in., respectively. The decrease in mean annual precipitation along with 

an increase in the percent of drainage area below an altitude 

of 6,000 ft (table 3) in the corresponding drainage areas above 

Comus and Imlay compared with the drainage areas above 

Palisade, Carlin, and Elko indicate that a greater percentage of 

precipitation was from lower elevations. The overall pattern 

of above and below mean annual precipitation volume in the 

drainage areas above Comus and Imlay was most similar to 

that for Rock Creek (fig. 23).

Relation of Annual Runoff to 

Precipitation

The effect of climate on annual runoff of the Humboldt 

River was evaluated by comparing estimates of annual runoff 

at each streamflow gage with annual precipitation volume in 

the drainage area above the respective gage. Annual runoff of 

the Humboldt River and its tributaries is affected not only by 

precipitation that falls during the same year as the runoff, but 

also from precipitation that fell in previous years because of 

water stored in impoundments and in aquifers. The effect of 

storage retained from year to year was accounted for in the 

analysis by minimizing the sum of the squares of the difference in rank between an effective precipitation volume and 

annual runoff.

The effective annual precipitation volume (Pe ) was estimated by taking fractions of annual precipitation volume 

(P0 ) for the year of runoff and from successive years prior 

to year of runoff (P P1 2 , Pn ) as described by Searcy and 

Hardison (1960, p. 44), where

Pe = + aP0 1 bP + + cP2 zPn, (1)

and the sum of the fractions (a b, ,c z  ) must equal unity. 

Annual runoff was assigned a number according to rank starting with the year of highest runoff as 1. The same procedure 

was used to determine rank of annual precipitation volume. 

The difference in rank between annual precipitation volume 

and runoff was squared and summed and provided a basis for 

comparing estimates of effective precipitation volume using 

a fraction of annual precipitation volume from each successive year prior to runoff. Effective precipitation volume was 

calculated by assigning a fraction to the year of runoff and to 

successive years prior to the year of runoff, and the square of 

the difference in rank was then calculated and summed for 

the effective precipitation volume. Different percentages were 

used until a minimum value of the sum of the squares between 

effective precipitation volume and runoff was determined. If 

fractions from prior years precipitation volumes decreased 

the sum of the squares then the precipitation volume from 

the prior years had an effect on annual runoff. The sum of the 

squares increased when the percentage of prior years precipitation volume was too large, thus an optimum number of years 

and percentages for each year was obtained using this method.

Minimum sum of the squares of the difference in rank 

between effective annual precipitation volume and runoff were 

calculated when fractions of precipitation volumes for the year 

of runoff (P0 ) plus two years prior the year of runoff 

(P P1 2 , ) were used to estimate the effective annual precipitation volume (table 7). Effective annual precipitation volume 

for Lamoille and Martin Creeks included small fractions (less 

than 0.05) for each of two years prior to the year of runoff suggesting little effect from storage changes in the drainage areas 

above the streamflow gages, whereas the streamflow gage on 

Annual Precipitation Volume 39
-40

-30

-20

-10

0

10

20

30

40

50

60

70

C Martin Creek near Paradise Valley, Nevada 

Mean annual precipitation volume = 203 thousand acre-feet 

Coefficient of variation = 0.24 

Drainage area = 112 thousand acres 

Mean annual precipitation = 21.7 inches 

-40

-30

-20

-10

0

10

20

30

40

50

60

B Rock Creek near Battle Mountain, Nevada 

Mean annual precipitation volume = 554 thousand acre-feet 

Coefficient of variation = 0.21 

Drainage area = 553 thousand acres 

Mean annual precipitation = 12 inches 

-20

-10

0

10

20

30

40

1953 1958 1963 1968 1973 1978 1983 1988 1993 1998

DEPARTURE FROM MEAN ANNUAL PRECIPITATION VOLUME, IN PERCENT 

A Lamoille Creek near Lamoille, Nevada 

Mean annual precipitation volume = 45 thousand acre-feet 

Coefficient of variation = 0.10 

Drainage area = 15.9 thousand acres 

Mean annual precipitation = 33.9 inches 

WATER YEAR 

Figure 23. Departures from mean annual precipitation volume in drainage area above streamflow gages on 

A, Lamoille; B, Rock; and C, Martin Creeks, water years 1953–99. Locations of streamflow gages are shown in 

figure 2.

40 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
Rock Creek had much higher fractions of annual precipitation 

volumes from the two years prior to runoff suggesting changes 

in storage affected annual runoff (either in aquifers or in Willow Creek Reservoir; fig. 4). Effective annual precipitation 

volume for streamflow gages along the Humboldt River also 

included fractions of the precipitation volume from two years 

prior to the year of runoff (table 7).

The least effect of prior years precipitation volumes for 

streamflow gages on the Humboldt River was estimated from 

the streamflow gage near Carlin, which is the first downstream 

gage from the South Fork of the Humboldt River. The South 

Fork and its tributaries drain most of the west side of the Ruby 

Mountains and even though a reservoir was built at the base of 

the Ruby Mountains (fig. 4), the higher percentage of precipitation for the same year as runoff suggests smaller changes 

in storage than for the other streamflow gages along the 

Humboldt River. The higher percentage for the same year of 

runoff at the Carlin gage is consistent with the Lamoille Creek 

gage. The gradually decreasing fraction in annual precipitation 

volume for the year of runoff at streamflow gages downstream 

of Carlin suggests that changes in storage (mostly in aquifers) 

are more important further downstream.

The effect of annual precipitation volume for years prior 

to the year of runoff on the relation of annual runoff to annual 

precipitation volume was tested in multiple-linear regression 

models whereby annual precipitation volume was separated 

into the year of runoff and successive years prior to the year of 

runoff. The models assumed both untransformed and transformed values for runoff and precipitation volume that were in 

the form of:

and (2)

 (3)

where is estimated annual runoff (response variable);

b b0 1 , ,b b2 3 4 , ,b are regression coefficients;

 P P0 1 , ,P P2 3 , are annual precipitation volume for year of 

runoff and successive years prior to year of 

runoff (explanatory variables); and

 is natural log or loge.

A stepwise regression was done with both models in 

which annual precipitation volume for successive years prior 

to the year of runoff (P P1 2 , ,P3 ) were added to the regression equation until the coefficient of the earliest year did not 

improve the regression equation and was not significant to 

a P-value (probability) of 0.05. The log transformed values 

resulted in a better regression model for all streamflow gages 

except for that on Lamoille Creek where untransformed data 

resulted in a better regression model. The selection of the 

proper model was made by plotting residual runoff (both transformed and untransformed) to the predicted runoff for possible 

trends and by plotting predicted runoff to actual runoff to be 

certain that the relation was generally linear with homogeneous variance (Helsel and Hirsch, 1992, p. 258).

Table 7. Fractions used to estimate effective precipitation volumes on basis of partitioning precipitation over three-year periods from 

1953 through 1999 in drainage areas above streamflow gages on Lamoille, Rock, and Martin Creeks, and above streamflow gages on 

Humboldt River near Elko, near Carlin, at Palisade, at Comus, and near Imlay, Nevada 

[Locations of streamflow gages are shown in figure 2]

Streamflow gage

Factor applied to annual precipitation1

Two years previous Previous year Year of runoff

Tributary streamflow gages

Lamoille Creek 0.01 0.01 0.98

Rock Creek .11 .11 .78

Martin Creek .01 .03 .96

Humboldt River streamflow gages

Near Elko .15 .21 .64

Near Carlin .03 .17 .80

At Palisade .14 .15 .71

At Comus .15 .23 .62

Near Imlay .16 .26 .58

1

 The first three-year period of effective precipitation volume corresponded to water years 1953–55; the year of annual runoff was 1955; the previous year was 

1954 and two years’ previous was 1953. Subsequent effective precipitation volumes were estimated by incrementing each year in the three-year period by one 

year. The percentage of precipitation for the year of runoff, previous year, and two years’ previous was estimated using a method to minimize the square of the 

difference in rank of effective precipitation to annual runoff as described by Searcy and Hardison (1960).

Annual Precipitation Volume 41

R P P P P Ù= + b b 0 1( )0 + + b b 2( )1 3( )2 + b4( )3 ,

lnR ln( ) P P ln( ) ln( ) P P ln( ) Ù= + b b 0 1 0 + + b b 2 1 3 2 + b4 3

R

Ù

ln
DEPARTURE FROM MEAN ANNUAL PRECIPITATION VOLUME, IN PERCENT 

Mean annual precipitation volume = 3.93 million acre-feet 

Coefficient of variation = 0.18 

Drainage area = 3.23 million acres 

Mean annual precipitation = 14.6 inches 

-30

-20

-100

10

20

30

40

50

1953 1958 1963 1968 1973 1978 1983 1988 1993 1998 C At Palisade, Nevada 

Mean annual precipitation volume = 3.46 million acre-feet 

Coefficient of variation = 0.17 

Drainage area = 2.78 million acres 

Mean annual precipitation = 14.6 inches 

-30

-20

-100

10

20

30

40

50

B Near Carlin, Nevada 

-30

-20

-100

10

20

30

40

50

A Near Elko, Nevada 

Mean annual precipitation volume = 2.20 million acre-feet 

Coefficient of variation = 0.18 

Drainage area = 1.78 million acres 

Mean annual precipitation = 14.9 inches 

WATER YEAR 

Figure 24. Departures from mean annual precipitation volume in drainage area above streamflow gages on 

the Humboldt River A, near Elko; B, near Carlin; C, at Palisade; D, at Comus; and E, near Imlay, Nevada, water 

years 1953–99. Locations of streamflow gages are shown in figure 2.

42 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
1953 1958 1963 1968 1973 1978 1983 1988 1993 1998

 Near Imlay, Nevada 

DEPARTURE FROM MEAN ANNUAL PRECIPITATION VOLUME, IN PERCENT 

-30

-40

-20

-10

0

10

20

30

40

50

E

D

Mean annual precipitation volume = 9.98 million acre-feet 

Coefficient of variation = 0.20 

Drainage area = 9.92 million acres 

Mean annual precipitation = 12.1 inches 

-30

-40

-20

-10

0

10

20

30

40

50

 At Comus, Nevada 

Mean annual precipitation volume = 8.20 million acre-feet 

Coefficient of variation = 0.19 

Drainage area = 8.02 million acres 

Mean annual precipitation = 12.3 inches 

WATER YEAR 

Annual Precipitation Volume 43

Figure 24. Continued.
Precipitation volume during the year of runoff was the 

only significant explanatory variable (P-value of less than 

0.05) for the tributary streamflow gages on Lamoille, Rock, 

and Martin Creeks, whereas precipitation volume during the 

previous year was also significant for all streamflow gages on 

the Humboldt River. These results, although less sensitive to 

prior years annual precipitation volume, are generally consistent with the method of minimizing the sum of squares of the 

difference in rank between precipitation volume and runoff 

summarized in table 8. The only exception was the Rock 

Creek gage where the multiple-linear regression model indicated that only the precipitation volume for the year of runoff 

was significant, whereas minimizing the sum of the squares 

of the difference in rank indicated fractions of the precipitation volume from the previous two prior years were important. 

Regression models of the runoff using the effective precipitation volume were the same to slightly better than those from 

the multiple linear regression. Thus, effective precipitation 

volumes determined by minimizing the sum of squares of the 

difference in rank was used in the analyses of trends.

Tributaries

The relation of annual runoff to effective precipitation 

volume for the streamflow gages on Lamoille, Rock, and 

Martin Creeks is shown in figure 25. The nearly linear relation 

between annual runoff and effective precipitation volume for 

Lamoille Creek indicates that sufficient precipitation occurs 

each year such that there are only minor year to year changes 

in storage, evapotranspiration, and in the percentage of the 

drainage area that contributes runoff, whereas the nonlinear 

power relation for the Martin Creek and Rock Creek gages 

indicates that there are much larger year to year changes in 

storage, evapotranspiration, and in the percentage of the drainage area that contributes runoff.

The streamflow gage on Rock Creek shows greater variability than the streamflow gage on Martin Creek such that 

there is much scatter in annual runoff to effective precipitation 

volume (fig. 25). The equations used to predict annual runoff 

and the coefficient of determination also are listed in the 

graph for each streamflow gage. The equations for streamflow 

gages on Martin Creek and Rock Creek include an additional 

term that is the bias correction factor because transforming a 

log-regression equation back into its original form results in 

a median estimate for the predicted value and not the mean 

(Helsel and Hirsch, 1992). The bias correction factor (BCF ) 

was estimated using a smearing estimate (Duan, 1983) that is 

equal to the mean of the individually transformed log residuals 

or

(4)

where ei is the difference of the predicted runoff minus runoff 

and n is the number of years used in the regression.

The greater variability between annual runoff and the 

effective precipitation volume from Lamoille Creek to Rock 

Creek corresponds to progressively larger percentages of 

land-surface altitudes less than 6,000 ft in the drainages (table 

3). Annual precipitation in the area below 6,000 ft is normally 

less than the annual evapotranspiration demand (Houghton and 

others, 1975, p. 62–64). Only occasionally is there sufficient 

precipitation during the winter months that produce runoff 

from the lower altitudes in the Martin Creek and Rock Creek 

drainages and from large areas in the Humboldt River drainage.

The considerable scatter among the individual estimates 

for Rock Creek is attributed to variations of when and where 

precipitation occurred in the drainage area during the year and 

the quantity of water in storage at the beginning of each year, 

and perhaps to the change in operation of the Willow Creek 

Reservoir as suggested by a change in mean monthly runoff 

after 1971 (fig. 11). The effect of antecedent conditions in 

the Rock Creek drainage is shown by nearly the same effective precipitation volume for 1965, 1984, 1995, and 1998, yet 

discharge was 38,000 acre-ft in 1965; 170,000 acre-ft in 1984; 

24,000 acre-ft in 1995; and 60,000 acre-ft in 1998. The higher 

than average precipitation years in 1965 and 1995 followed 

relatively long periods of generally below average precipitation whereas 1984 was at the end of a relatively long period 

of above average precipitation (11 of 16 years from 1969–84 

were above average) and followed two consecutive years of 

above average precipitation (fig. 23).

Humboldt River

The relation between annual runoff and the effective precipitation volume at streamflow gages on the Humboldt River 

are similar in form to those for Rock and Martin Creeks (fig. 

26), although the coefficient of determination (R2 between 

0.73 and 0.75) suggests similar variation as Martin Creek and 

much less variation than Rock Creek. However, antecedent 

conditions similar to that of Rock Creek also affect annual 

runoff along the Humboldt River. Annual runoff was consistently greater along the river in 1983 and 1984 than in 1965, 

1995, and 1998. Annual runoff in 1984 was more than double 

that in 1998 at the five streamflow gages on the Humboldt 

River, even though effective precipitation volume in 1984 

was only about 10 percent more than in 1998 in the drainages 

above Elko, Carlin, and Palisade (fig. 26A–C) and were nearly 

equal at Comus and Imlay (fig. 26D–E). Water years 1965, 

1995, and 1998 all were followed by relatively long periods 

of below mean annual precipitation and consequently, much 

of the effective precipitation volume during 1965, 1995, and 

1998 may have gone to replenishing ground-water storage. 

Although the effective precipitation volume was greatest in 

1984 for the five streamflow gages, the year culminated a 

16-year period (1969–84) of generally above mean annual 

precipitation (fig. 24) in which much of the available groundwater storage may have been filled.

44 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999

BCF

e

n

i

i

n

= =

åexp( )

, 1
Table 8. Effective precipitation volumes estimated for water years 1955–99 in drainage areas above streamflow gages on Lamoille, 

Rock, and Martin Creeks, and on Humboldt River near Elko, near Carlin, at Palisade, at Comus, and near Imlay, Nevada

[Volumes are in millions of acre-feet. Locations of streamflow gages are shown in figure 2. Shaded areas for streamflow gages on Humboldt River for 1984 and 

1998 are used to show differences in annual precipitation during two periods of above mean precipitation]

Year Lamoille Creek Rock Creek Martin Creek Humboldt River 

near Elko near Carlin at Palisade at Comus near Imlay

1955 0.0445 0.375 0.159 1.652 2.618 2.931 5.779 6.965

1956 0.0407 0.531 0.205 2.087 3.372 3.733 7.044 8.431

1957 0.0399 0.515 0.195 2.124 3.444 3.784 7.585 9.153

1958 0.0400 0.499 0.236 2.129 3.322 3.782 7.970 9.712

1959 0.0457 0.423 0.171 1.883 2.885 3.330 6.717 8.235

1960 0.0463 0.380 0.172 1.822 2.785 3.195 6.223 7.514

1961 0.0458 0.393 0.176 1.751 2.761 3.100 6.477 7.755

1962 0.0407 0.504 0.175 2.081 3.328 3.694 7.663 9.147

1963 0.0432 0.575 0.178 2.347 3.790 4.168 8.604 10.317

1964 0.0423 0.547 0.174 2.200 3.480 3.937 8.652 10.492

1965 0.0449 0.709 0.192 2.668 4.231 4.783 9.932 11.939

1966 0.0483 0.455 0.145 1.891 2.935 3.383 7.365 9.106

1967 0.0452 0.556 0.201 2.184 3.327 3.916 7.998 9.659

1968 0.0491 0.533 0.172 2.076 3.359 3.718 7.553 9.132

1969 0.0378 0.584 0.211 2.359 3.729 4.200 8.708 10.483

1970 0.0447 0.632 0.229 2.470 3.941 4.412 9.131 11.078

1971 0.0423 0.630 0.206 2.508 3.966 4.480 9.134 11.116

1972 0.0476 0.509 0.177 2.167 3.338 3.856 7.803 9.553

1973 0.0476 0.594 0.204 2.270 3.538 4.077 8.497 10.273

1974 0.0496 0.450 0.177 1.915 3.009 3.414 7.184 8.832

1975 0.0448 0.620 0.205 2.301 3.649 4.144 8.759 10.573

1976 0.0435 0.563 0.193 2.139 3.465 3.855 8.527 10.425

1977 0.0424 0.443 0.175 1.905 2.891 3.390 7.410 9.109

1978 0.0450 0.653 0.214 2.470 3.923 4.415 9.231 11.051

1979 0.0431 0.539 0.178 2.199 3.530 3.913 8.528 10.376

1980 0.0403 0.633 0.227 2.565 3.980 4.557 9.381 11.346

1981 0.0466 0.436 0.161 1.905 2.948 3.386 7.358 9.043

1982 0.0437 0.635 0.315 2.537 3.941 4.507 8.866 10.760

1983 0.0499 0.656 0.291 2.595 4.256 4.629 9.729 11.885

1984 0.0407 0.741 0.330 3.000 4.753 5.330 11.131 13.635

1985 0.0492 0.551 0.195 2.355 3.614 4.184 9.121 11.295

1986 0.0522 0.580 0.251 2.377 3.575 4.228 8.695 10.668

1987 0.0422 0.474 0.178 1.997 3.119 3.554 7.758 9.461

1988 0.0386 0.495 0.145 1.936 2.988 3.471 7.662 9.291

1989 0.0412 0.478 0.264 1.978 3.102 3.513 7.616 9.311

1990 0.0414 0.498 0.159 1.951 3.104 3.501 7.635 9.293

1991 0.0410 0.489 0.195 1.957 3.080 3.500 7.486 9.150

1992 0.0400 0.455 0.129 1.868 2.922 3.333 7.010 8.481

1993 0.0468 0.608 0.269 2.342 3.753 4.185 8.354 10.114

1994 0.0419 0.497 0.141 1.984 3.183 3.562 7.516 9.202

1995 0.0490 0.714 0.283 2.656 4.199 4.764 9.511 11.536

1996 0.0482 0.585 0.233 2.358 3.809 4.215 8.804 10.830

1997 0.0569 0.664 0.251 2.737 4.288 4.871 9.912 12.070

1998 0.0494 0.729 0.289 2.733 4.395 4.911 10.950 13.399

1999 0.0486 0.574 0.202 2.416 3.736 4.307 9.310 11.542

Annual Precipitation Volume 45
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Figure 25. Relation between annual runoff and effective precipitation volume at streamflow 

gages on A, Lamoille; B, Rock; and C, Martin Creeks, water years 1955–99. Location of 

streamflow gages is shown in figure 2.

46 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
Perhaps another reason for the lack of annual runoff in 

response to precipitation in 1998 is that a large percentage 

of the increased precipitation was in the lower-altitude areas 

and less in the higher Ruby Mountains and Eastern Humboldt 

Range. This is supported by the greater positive departures in 

annual precipitation for the stations at Beowawe, Battle Mountain, and Winnemucca compared with stations at Lamoille 

and Arthur 4NW (fig. 3), and by the greater positive offsets 

used to compute annual precipitation for the lower-altitude 

areas of region 3 and all of region 7 in 1998 compared with 

1984 (table 5). Thus, estimated annual precipitation in 1998 

was about 10 percent less than in 1984 for the streamflow 

gages at Palisade, near Carlin, and near Elko, whereas annual 

precipitation in 1998 was about 1 percent more than in 1984 

for the streamflow gages at Comus and near Imlay (table 6). 

Much of the precipitation in the lower-altitude areas likely 

contributed little runoff to the Humboldt River; rather much of 

this precipitation was lost to evapotranspiration or infiltrated to 

ground water.

Trends in the ratio of annual runoff to effective precipitation volume during 1955–99 show a cyclical pattern related 

to the effective precipitation volume (fig. 27). The ratio of 

runoff to effective precipitation volume for the Lamoille Creek 

gage ranged from 0.35 in 1959 to 0.99 in 1999 and the mean 

was 0.7. The mean ratio indicates that about 70 percent of the 

effective precipitation became runoff. Ratios approaching 1 

for the streamflow gage on Lamoille Creek indicate that either 

there was little evapotranspiration relative to the increased precipitation or more likely that precipitation was underestimated. 

A possible reason for decreased evapotranspiration during 

years of above mean annual precipitation is that the heavy 

snowpack in the drainage may result from cooler temperatures 

caused by a prolonged melt. The ratio of annual runoff to the 

effective precipitation volume was directly affected by the 

volume being well below or above the mean. Higher ratios 

were calculated during years when the effective precipitation 

volume was above the mean and lower ratios were calculated 

during years below the mean (fig. 27).

A similar pattern is shown for the streamflow gages on 

Rock and Martin Creeks except the ratio of annual runoff to 

effective precipitation volume is much lower (fig. 27). The 

ratio for Rock Creek ranged from about 0.01 in several years 

to 0.2 in 1984 and the mean was 0.05. This is much lower than 

either of the streamflow gages on Lamoille and Martin Creeks, 

and suggests that only 5 percent of the total precipitation in the 

basin became runoff at the streamflow gage on Rock Creek. 

The remaining 95 percent was either lost to evapotranspiration 

or became ground water that did not return to Rock Creek.

The inability to correctly estimate the actual volume of 

precipitation that had fallen in the drainage area above each 

gage results in some variability in the ratio of runoff to precipitation that can not be explained by an increase or a decrease 

in effective precipitation volume. For example, the ratio of 

runoff to effective precipitation volume for the streamflow 

gage on Martin Creek increased in 1962 yet the estimated 

effective precipitation volume was nearly the same during 

1960–63 (fig. 27). Similarly, the ratio of runoff to effective 

precipitation volume for the streamflow gage on Rock Creek 

increased in 1989, even though the effective precipitation 

volume remained well below the mean during 1987–89. These 

variations in the ratio of runoff to effective precipitation volume are likely caused by errors inherent in estimating annual 

precipitation volumes in drainages with sparse measurements 

of precipitation, although some of the variations may be the 

result of changes in storage of water in snow, surface reservoirs, and ground water.

The ratio of annual runoff to effective precipitation 

volume during 1955–99 at the five streamflow gages on the 

Humboldt River show trends similar to those for Lamoille, 

Rock, and Martin Creeks (fig. 28). The ratio of runoff to the 

effective precipitation volume for Elko, Carlin, and Palisade 

was nearly the same for all three streamflow gages. The ratios 

range from about 0.02 in 1955, 1959, 1961, and 1992 to as 

much as 0.27 in 1984. High ratios generally correspond with 

periods of above mean effective precipitation volume and low 

ratios generally correspond with periods of below mean effective precipitation volume (fig. 28) The ratios are consistent 

with the power-law equations (fig. 26) in which the ratio of 

runoff to effective precipitation volume remains a power-law 

with a positive exponent. The mean ratio was 0.08 for the 

three streamflow gages and indicates that on average about 8 

percent of the effective precipitation volume became runoff 

and that 92 percent was lost to evapotranspiration or to ground 

water. Although streamflow is lost to ground water along 

much of the Humboldt River, ground-water discharge during 

the late summer is sufficient to maintain flow at Elko, Carlin, 

and Palisade (fig. 18). Mean annual ground-water discharge to 

the Humboldt River between Carlin and Palisade was estimated at 12,000 acre-ft during 1946–81 (Maurer and others, 

1996, p. 28).

The streamflow gages at Comus and near Imlay have similar patterns in the ratio of annual runoff to effective precipitation volume to the three upstream gages, although the ratios 

are much lower (fig. 28). The mean ratio was 0.03 for Comus 

and the mean ratio was 0.02 for Imlay. These low ratios suggest that almost all of the precipitation in the drainage areas 

above the two streamflow gages was lost to evapotranspiration 

or to ground water. Finally, the pattern of generally higher 

ratios of runoff during periods when the effective precipitation 

volume was above the mean effective precipitation volume and 

decreasing ratios during periods of below the mean (fig. 28) 

for Comus and Imlay was nearly the same as the pattern for 

the upstream gages. The rapid rise in the ratio from 1982 to 

1984 is consistent with consecutive years where effective precipitation volume was above the mean effective precipitation 

volume, whereas the rapid fall following 1984 is consistent 

with a marked decline in the effective precipitation volume.

Annual Precipitation Volume 47
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Figure 26. Relation between annual runoff and effective precipitation volume at streamflow 

gages on Humboldt River A, near Elko; B, near Carlin; C, at Palisade; D, at Comus; and E, near Imlay, 

Nevada, water years 1955–99. Locations of streamflow gages are shown in figure 2.

48 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
ANNUAL RUNOFF, IN MILLIONS OF ACRE-FEET 

E Near Imlay, Nevada 

0

0.4

0.8

1.2

1.6

6 7 8 9 10 11 12 13

EFFECTIVE PRECIPITATION VOLUME, IN MILLIONS OF ACRE-FEET 

y = (0.0000002 * x 5.949

R2 = 0.74 

1983

1984

1998

1965

 ) * 1.135

14

D At Comus, Nevada 

0

0.4

0.8

1.2

1.6

5 6 7 8 9 10 11 12 13

y = (0.000001 * x 5.689

R2 = 0.74 

1984

1983

1998

1965

 ) * 1.120

Effects of Ground-Water Withdrawals 

on Annual Runoff

Ground-water withdrawals in the Humboldt River 

Basin have the potential for decreasing annual runoff in the 

Humboldt River. The effect is dependent on the quantity 

and proximity of the ground-water withdrawals to the river 

(Glover and Balmer, 1954; Heath, 1987; Winter and others, 

1998). The withdrawal of large quantities of ground water 

in areas distant from the Humboldt River or the withdrawal 

of small quantities near it may have no measurable effect 

on runoff. However, if withdrawals of large quantities of 

ground water are sustained over time, runoff may eventually be reduced. Reduction in streamflow has been attributed 

to ground-water withdrawals in many parts of the country 

(Glennon, 2002). Some of the more significant reductions in 

streamflow have occurred along the Arkansas River in western Kansas as a result of agricultural withdrawals (Sophocleous, 2000) and in the loss of sustained baseflow during the 

fall that once supported Salmon on the Cosumnes River, near 

Sacramento, California (Fleckenstein and others, 2004).

Unlike the reductions determined from the marked 

differences in runoff and baseflow between gages for the 

Arkansas and Cosumnes Rivers, reductions in annual runoff 

and baseflow along the Humboldt River from 1950–99 were 

not obvious (figs. 15–20). Thus, multiple linear-regression 

analyses were done using annual runoff at streamflow gages 

on the Humboldt River to assess the effects of ground-water 

withdrawals. The analyses were done by converting all 

volumes to millions of acre-feet (to be consistent with the 

effective precipitation volumes) and then taking the log transform of annual runoff of the upstream gage, and the effective 

precipitation volume, ground-water withdrawals, and mine 

discharges in the drainage area between gages. The general 

form of the equation used is:

(5)

where is estimated annual runoff at downstream 

gage (response variable);

b b0 1 , ,b b2 3 4 , ,b are regression coefficients;

 is annual runoff at upstream gage, millions 

of acre-feet; 

Figure 26. Continued.

Effects of Ground-Water Withdrawals on Annual Runoff 49

lnRdn ln( ) Rup ln( ) Pef

Ù

= + b b 0 1 + + b2

b3 b4 ln( ) W D gw + ln( ) m ,

Rdn

Ù

Rup
0

0.5

1

1.5

2

0

0.5

1

1.5

2

Lamoille Creek, mean is 0.7 Above streamflow gage 

A Lamoille Creek

 Ratio of annual runoff to

effective precipitation volume

Ratio of effective precipitation volume to mean

R

A

TIO

O

F

R

U

N

O

F

F

T

O

E

F

F

E

C

TIV

E

P

R

E

CIPIT

A

TIO

N

V

O

L

U

M

E

R

A

TIO

O

F

E

F

F

E

C

TIV

E

P

R

E

CIPIT

A

TIO

N

V

O

L

U

M

E

T

O

M

E

A

N

0

0.2

0.4

0.6

0.8

1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

0

0.5

1

1.5

2

WATER YEAR

Martin Creek, mean is 0.13

Rock Creek, mean is 0.05 Above streamflow gage on Martin Creek

Above streamflow gage on Rock Creek

B Rock and Martin Creeks

 Ratio of annual runoff to 

effective precipitation volume

Ratio of effective precipitation volume to mean

Figure 27. Ratios of annual runoff to effective precipitation volume at streamflow gages on A, Lamoille Creek; and 

B, Rock and Martin Creeks, and effective precipitation volume to mean effective precipitation volume above each 

streamflow gage, water years 1955–99. Locations of streamflow gages are shown in figure 2.

50 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
Annual ground-water withdrawals estimated during 

1955–99 (fig. 8) were partitioned into each of the drainage 

areas between streamflow gages except for the streamflow 

gage near Elko, which included the entire drainage area above 

the gage (table 9). Only the regression equations that were 

used to predict runoff at the streamflow gages at Palisade and 

Comus included mine discharge to the Humboldt River. Mine 

discharge was assumed to be a small volume (1 acre-ft) for 

years in which no water was discharged to the river to allow 

for transformation to a natural log. Not included in the models 

were estimates of annual evapotranspiration in the drainage 

areas between gages. Also, annual diversions for irrigation 

along the river and to the Pitt-Taylor Reservoirs were not 

included in the models because data were not available for all 

years.

The inclusion of ground-water withdrawals into the 

regression equations for the streamflow gages near Elko and 

Carlin did not substantially improve the regression equation 

nor was the P-value (significance level attained by the data; 

Helsel and Hirsch, 1992, p. 108–109) less than a probability 

of 0.05 (or 5 percent chance that it should have been accepted) 

as listed in table 10. Only the effective precipitation volume 

was significant in the regression equation for the streamflow 

is effective precipitation volume between streamflow

gages, millions of acre-feet;

is annual ground-water withdrawals between streamflow

gages, millions of acre-feet;

is annual mine discharge to Humboldt River or a tributary 

stream between streamflow gages, millions of acre-feet;

and 

is natural log or loge.

The analyses for the uppermost streamflow gage near 

Elko did not include an upstream gage and thus, all precipitation and ground-water withdrawals in the drainage area above 

the gage was included in the stepwise regression. The models 

used the log transformed values because they were found to 

have a more constant variance throughout the range of the 

explanatory variables (Rup, , Pef W D gw, m ). Also, the use of 

log transformed values was consistent with the results of the 

regression models used to predict runoff from the effective 

precipitation volume for each of the streamflow gages, and 

was consistent with the findings that channel infiltration losses 

can be estimated from streamflow using a power-law equation 

(Burkham, 1970, p. D271).

0

0.1

0.2

0.3

0.4

1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

0

0.5

1

1.5

2

WATER YEAR

R

A

TIO

OF A

N

N

U

AL R

U

N

OFF T

O EFFEC

TIVE PRECIPIT

A

TIO

N

V

OLU

ME

R

A

TIO

OF EFFEC

TIVE PRECIPIT

A

TIO

N

V

OLU

ME TO MEAN

Near Elko, mean is 0.08

Near Carlin, mean is 0.08

At Palisade, mean is 0.08

At Comus, mean is 0.03

Near Imlay, mean is 0.02

Above streamflow gage near Carlin 

 Ratio of annual runoff to 

effective precipitation volume 

Ratio of effective precipitation 

 volume to mean 

Above streamflow gage at Comus 

Figure 28. Ratios of annual runoff to effective precipitation volume at streamflow gages on Humboldt River, and 

ratios of effective precipitation volume to mean effective precipitation volume above streamflow gages near Carlin 

and at Comus. Locations of streamflow gages are shown in figure 2.

Effects of Ground-Water Withdrawals on Annual Runoff 51

Pef

W gw

D m

ln
Table 9. Annual ground-water withdrawals estimated for water years 1955–99 in drainage areas above streamflow 

gage on Humboldt River near Elko, and between selected streamflow gages from Elko to Imlay, Nevada

[Volumes are in acre-feet, rounded to two significant figures. Locations of streamflow gages are shown in figure 2]

Year

Ground-water withdrawals

Upstream of streamflow 

gage near Elko

Between streamflow gages 

near Elko and 

near Carlin

near Carlin and 

at Palisade

at Palisade and at 

Comus

at Comus and 

near Imlay

1955 690 2,600 10 5,500 5,700

1956 700 2,600 10 6,000 6,600

1957 750 2,700 10 6,400 7,000

1958 760 2,700 10 9,000 7,700

1959 770 2,900 10 9,600 8,900

1960 870 3,200 10 12,000 9,100

1961 870 3,300 10 15,000 9,900

1962 880 3,300 110 15,000 14,000

1963 980 3,400 140 19,000 14,000

1964 980 3,500 140 23,000 15,000

1965 980 3,500 140 26,000 16,000

1966 980 3,600 140 27,000 18,000

1967 1,100 3,700 140 30,000 20,000

1968 1,100 3,800 140 33,000 13,000

1969 1,200 3,900 140 34,000 16,000

1970 1,300 4,000 140 34,000 18,000

1971 1,400 4,200 140 39,000 21,000

1972 1,400 4,400 140 40,000 27,000

1973 1,400 4,600 140 40,000 39,000

1974 1,500 4,700 140 40,000 51,000

1975 1,600 4,900 140 41,000 53,000

1976 1,600 5,000 140 46,000 60,000

1977 1,600 5,300 140 55,000 65,000

1978 1,900 5,400 140 67,000 72,000

1979 1,900 5,600 140 73,000 75,000

1980 2,000 5,800 150 81,000 73,000

1981 2,100 6,000 150 89,000 78,000

1982 2,300 6,200 150 79,000 74,000

1983 2,300 6,100 150 66,000 58,000

1984 2,300 6,300 160 64,000 62,000

1985 2,300 6,800 170 63,000 63,000

1986 2,400 6,800 180 55,000 62,000

1987 2,400 7,500 360 57,000 64,000

1988 2,400 8,800 2,300 61,000 69,000

1989 2,500 9,800 5,400 60,000 72,000

1990 2,500 10,000 6,200 83,000 74,000

1991 2,500 9,900 6,600 61,000 72,000

1992 2,500 12,000 6,900 170,000 79,000

1993 2,500 12,000 12,000 200,000 86,000

1994 2,600 13,000 23,000 190,000 110,000

1995 2,700 13,000 25,000 200,000 100,000

1996 2,700 14,000 26,000 140,000 110,000

1997 2,900 13,000 29,000 180,000 120,000

1998 2,900 14,000 27,000 260,000 120,000

1999 2,900 15,000 17,000 260,000 77,000

52 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
gage near Elko, whereas both the annual runoff near Elko 

and the effective precipitation volume were significant for the 

streamflow gage near Carlin. However, neither precipitation 

nor ground-water withdrawals were significant explanatory 

variables in the regression equation for the streamflow gage at 

Palisade even though runoff from Maggie, Susie, and Marys 

Creeks and ground-water discharge contribute additional flow 

to the Humboldt River between Carlin and Palisade. Perhaps 

ground-water discharge and runoff from the tributary streams 

had similar variation to the annual runoff at Carlin such that all 

the variability at Palisade was explained by the variability in 

annual runoff at Carlin.

The regression analysis at Palisade was divided into two 

periods (1955–91 and 1992–99; table 10) because groundwater withdrawals were correlated to mine discharge. The 

expectation was for ground-water withdrawals to decrease 

runoff and mine discharge to increase runoff, which could 

affect the regression equation for the longer period. Neither 

ground-water withdrawals during 1955–91 nor mine discharge 

during 1992–99 were significant to a probability value of 0.05 

indicating that these variables had no effect on annual runoff 

at Palisade. The analysis is consistent with the results that the 

difference in runoff at Carlin and Palisade did not change during 1950–99 (fig. 16).

The regression equations for the streamflow gage at 

Comus showed that either ground-water withdrawals or mine 

discharge was significant to runoff but not both (table 10). The 

coefficient for ground-water withdrawals was positive and 

thus, its effect was to increase runoff at Comus. Because of the 

effect of discharge of water from Betze and Lone Tree Mines, 

the regression analysis was divided into the same two periods 

as was done for the streamflow gage at Palisade. Groundwater withdrawals during 1955–91 were not significant to a 

probability of 0.05, whereas mine discharge during 1992–99 

was significant to a probability of 0.01 and resulted in an 

overall increase in annual runoff during 1992–99 that was not 

explained by effective precipitation. Runoff into the Humboldt 

River from ungaged tributaries between Palisade and Comus 

undoubtedly contributed annual runoff to the river during 

1992–99 but the contribution could not be distinguished from 

annual runoff at Palisade and the discharge of water directly 

to the river from the mines. Thus, the coefficients for annual 

runoff at Palisade and for mine discharge between Palisade 

and Comus listed in table 10 likely incorporate runoff from 

tributary streams.

Ground-water withdrawals in the reach between Comus 

and Imlay was significant in the regression analysis (table 10), 

although the effect is small and the P-value of 0.04 is close to 

the 0.05 probability used to reject coefficients of explanatory 

variables. Nonetheless, the negative coefficient along with an 

overall regression equation that improved the R2 and lowered the standard error (table 10) suggests that ground-water 

withdrawals in the reach between Comus and Imlay may have 

caused a decrease in annual runoff at Imlay. Much of decrease 

was between 1970 and 1998 when ground-water withdrawals 

increased six fold (table 9). The results are reasonable because 

considerable ground-water withdrawals for irrigation occurred 

near the Humboldt River between Golconda and Imlay (fig. 4). 

A numerical model simulation of ground-water withdrawals at 

the southern end of Paradise Valley and in the Humboldt River 

Valley north of Golconda resulted in a net increase in groundwater flow from Humboldt River Valley to Paradise Valley 

(Prudic and Herman, 1996). Prior to the ground-water withdrawals in Paradise Valley, ground-water flow from Paradise 

Valley contributed baseflow to the river (Cohen and others, 

1965). Although unknown, similar effects may have occurred 

west of Winnemucca where ground-water flow from Grass 

Valley increased flow along the river between Winnemucca 

and the Imlay streamflow gage during the early 1960’s (Cohen 

and others, 1965).

Another possibility for the significance of ground-water 

withdrawals in the reach between the Comus and Imlay 

streamflow gages is that the ground-water withdrawals acted 

as a surrogate to diversions along the Humboldt River, either 

for irrigation along the river or to temporarily store excess 

streamflow in the Pitt-Taylor Reservoirs (fig. 4). However, the 

trend in ground-water withdrawals likely was different than 

the trend in surface-water diversions. Diversions along the 

Humboldt River between Comus and Imlay have not changed 

since adjudication of the Humboldt River in the 1930’s and 

diversions to the Pitt-Taylor Reservoirs only occur during 

years when Rye Patch Reservoir is at its maximum storage 

capacity such that the diversion of water into the Pitt-Taylor 

Reservoirs follows the pattern on annual runoff at the Comus 

streamflow gage and not that from ground-water withdrawals.

Summary and Conclusions

Since 1990, ground-water withdrawals in the Humboldt 

River Basin have increased as a result of a general increase 

in population and development of large gold mines. Trends 

in streamflow at five long-term streamflow gages on the 

Humboldt River between Elko and Imlay, Nevada and at three 

streamflow gages on tributary streams were analyzed to evaluate effects of climate variability and ground-water withdrawals 

on flows along the Humboldt River. The study is part of the 

Humboldt River Basin Assessment by the USGS in cooperation with the NDCNR. The study is based on daily mean 

discharge at each of the streamflow gages and precipitation 

measured at 36 stations in or adjacent to the Humboldt River 

Basin from 1950 through 1999.

Ground water is, and historically has been, pumped in 

the Humboldt River Basin for municipal, domestic, power 

generation, irrigation, mining, and stock purposes. Groundwater withdrawals for these purposes were estimated annually from 1950–99. Ground-water withdrawals were less than 

10,000 acre-feet in the basin upstream of Rye Patch Reservoir 

in 1950, increased to more than 160,000 acre-feet by 1981 as 

a result of pumping for irrigation, and increased to more than 

420,000 acre-feet in 1998 because of the need to dewater gold 

Effects of Ground-Water Withdrawals on Annual Runoff 53
Table 10. Results of multiple linear regression models to estimate runoff at streamflow gages along the Humboldt River from Elko to 

Imlay, Nevada 

[Locations of streamflow gages are shown in figure 2. Symbols: --, explanatory variable was not included in regression model. Abbreviation, P-value is probability value. Shaded lines represent the best regression model for each gage and period]

Period

Natural log of explanatory variablesa

Interceptb P-value

Runoff at upstream 

gage Precipitation

Ground-water 

withdrawals

Mine water 

discharged to 

Humboldt River Coefficient of 

determination 

(R2)

Standard 

Slope error b

Pvalue SlopebPvalue SlopebPvalue SlopebPvalue

Humboldt River near Elko

1955–99 -6.14 <0.01 -- -- 5.30 <0.01 -- -- -- -- 0.740 0.432

1955–99 -7.90 <0.01 -- -- 5.60 <0.01 -0.23 0.19 -- -- 0.754 0.425

Humboldt River near Carlin

1955–99 -0.009 <0.01 0.825 <0.01 0.469 <0.01 -- -- -- -- 0.986 0.090

1955–99 -0.009 <0.01 0.825 <0.01 0.469 <0.01 -0.008 0.77 -- -- 0.986 0.091

Humboldt River at Palisade

1955–99 0.118 <0.01 0.996 <0.01 -- -- -- -- -- -- 0.998 0.035

1955–99 0.111 <0.01 0.997 <0.01 -0.011 0.74 -- -- -- -- 0.998 0.035

1955–99 0.118 <0.01 0.996 <0.01 -- -- <-0.001 0.99 -- -- 0.998 0.035

1955–99 0.118 <0.01 0.996 <0.01 -- -- -- -- <0.001 0.90 0.998 0.035

1955–91 0.118 <0.01 0.996 <0.01 -- -- -- -- -- -- 0.998 0.036

1955–91 0.115 <0.01 0.997 <0.01 -0.004 0.93 -- -- -- -- 0.998 0.036

1955–91 0.111 <0.01 0.997 <0.01 -- -- <-0.002 0.53 -- -- 0.998 0.036

1992–99 0.117 <0.01 0.991 <0.01 -- -- -- -- -- -- 0.998 0.035

1992–99 0.072 <0.01 1.003 <0.01 -0.083 0.45 -- -- -- -- 0.999 0.036

1992–99 0.117 <0.01 0.997 <0.01 -- -- -- -- <0.001 0.61 0.998 0.037

Humboldt River at Comusc

1955–99 -1.095 <0.01 1.101 <0.01 0.74 <0.01 -- -- 0.004 0.03 0.988 0.105

1955–99c -0.676 <0.01 1.122 <0.01 0.519 0.01 0.053 0.01 -- -- 0.988 0.105

1955–91 -1.116 <0.01 1.112 <0.01 0.687 <0.01 -- -- -- -- 0.990 0.096

1955–91 -0.577 0.16 1.134 <0.01 0.445 0.04 0.047 0.10 -- -- 0.990 0.094

1992–99 -1.855 0.18 1.018 <0.01 1.159 0.15 -- -- -- -- 0.980 0.163

1992–99 2.661 0.07 0.912 <0.01 -0.630 0.27 -- -- 0.575 <0.01 0.997 0.071

1992–99 1.263 <0.01 0.942 <0.01 -- -- -- -- 0.451 <0.01 0.996 0.076

Humboldt River near Imlay

1955–99 -0.155 <0.01 1.050 <0.01 -- -- -- -- -- -- 0.987 0.111

1955–99 -0.425 <0.01 1.003 <0.01 0.341 0.06 -- -- -- -- 0.989 0.108

1955–99 -0.768 <0.01 0.981 <0.01 0.609 <0.01 -0.046 0.04 -- -- 0.990 0.104

a

Natural log values were calculated from volumes for each explanatory variable reported in millions of acre-feet. Explanatory variables include annual runoff 

from upstream gage, and effective precipitation volumes, ground-water withdrawals, and water discharged to Humboldt River or tributary from mining operations, except for streamflow gage near Elko, which included effective precipitation volumes and ground-water withdrawals in drainage area above the gage. Time 

periods were divided into two intervals for the streamflow gages at Palisade and Comus because of the correlation between ground-water withdrawals and mine 

discharge. 

b

Intercept and slope are coefficients determined from multiple linear regressions using equation 5. 

c

Positive coefficient for ground-water withdrawals is opposite in sign from expected as it should lower the natural log value of the predicted runoff, thus the 

model was rejected in favor of the one that used mine discharge. 

54 Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–1999
mines that were below the water table. Part of the groundwater withdrawals for mining operations was discharged back 

to the Humboldt River or to Maggie Creek, a tributary of 

the Humboldt River. The maximum annual volume of water 

discharged to the Humboldt River or to Maggie Creek was 

96,700 acre-ft in 1998.

Annual runoff along the Humboldt River and its tributaries is highly variable. Runoff in the basin above Palisade 

is dominated by snowmelt mostly from high altitude in the 

Ruby Mountains, East Humboldt Range, and Jarbidge and 

Independence Mountains. Annual runoff generally increases 

from Elko to the Palisade gages because of tributary inflow 

and ground-water discharge. Ground-water discharge during 

late summer into winter maintains a baseflow in the Humboldt 

River upstream of Palisade. Annual runoff generally decreases 

downstream of Palisade because of irrigation diversions, infiltration of streamflow into alluvium, and evapotranspiration. 

However, annual runoff at Comus downstream of Palisade 

exceeded the annual runoff at Palisade during 1983–84 and 

again during 1996–99. Greater annual runoff at Comus than 

Palisade during 1983–84 resulted from well above annual 

mean precipitation and accumulation of snow at lower altitudes throughout much of the drainage basin, whereas greater 

annual runoff during 1996–99 was a result of above annual 

mean precipitation combined with the discharge of water from 

mining operations into the Humboldt River.

The daily discharge at Comus prior to the discharge of 

water directly into the river from mining operations was minimal during late summer to early winter because of insufficient 

baseflow from ground-water discharge. Beginning in 1992, 

daily discharge at Comus and Imlay increased markedly during the late summer to early winter as a result of added flow 

from the mining operations. However, the marked increase 

was much less at Imlay indicating that part of the water 

discharged to the river by the mines either infiltrated into the 

alluvium or was diverted prior to reaching the streamflow gage 

near Imlay.

The effect of climate on annual runoff of the Humboldt 

River was evaluated by comparing annual runoff at each 

streamflow gage with estimates of the annual precipitation volume in the drainage area above each gage. Precipitation generally is greater in the mountains than in the adjacent valleys, 

and is generally greater at the same altitude in the northern 

half of basin than in the southern half because of how storms 

track across the basin. Consequently, the basin was divided 

into seven regions to account for the variability in precipitation 

and a relation between mean annual precipitation and altitude 

was determined for each region. The relation that was developed for each region was then adjusted upward or downward 

on the basis of annual precipitation measured at stations in 

or near each of the regions. The annual precipitation volume 

was then estimated on the basis of the volume of precipitation 

within 1,000-ft altitude intervals in each region.

Because both surface and ground water storage within 

the drainage area above each streamflow gage has an effect 

on runoff, an effective precipitation volume was estimated 

by minimizing the square of the difference in rank of annual 

precipitation and runoff. The lowest square of the difference in 

rank was estimated when the effective precipitation included 

a fraction of precipitation from each of two years previous 

to the year of runoff. Even though the effective precipitation 

volume was an attempt to account for changes in storage, 

there was considerable variation between annual runoff and 

effective precipitation volume at all streamflow gages. Linear 

regression models were used to determine the relation between 

annual runoff and effective precipitation volume. Overall 

variations were reduced when the annual runoff and effective 

precipitation volumes were transformed into log values at all 

streamflow gages except those for Lamoille Creek. The logtransformation results in a power-law equation whereby runoff 

increased exponentially with increased precipitation. 

Although there was considerable annual variation 

between annual runoff and the effective precipitation volume, the ratio of annual runoff to the effective precipitation 

volume was generally higher during periods when the effective precipitation volume was greater than the mean effective 

precipitation volume and was lower during periods that were 

below the mean effective precipitation volume. Highest ratios 

were estimated for Lamoille Creek. Annual runoff at Lamoille 

Creek increased linearly with increased precipitation, and on 

average about 70 percent of the effective precipitation volume 

became runoff. This indicates that on average about 30 percent 

of the effective precipitation volume was lost to evapotranspiration or to ground water that did not discharge back to the 

creek upstream of the gage.

Lowest ratios of runoff to effective precipitation volume 

were estimated on the Humboldt River at the streamflow gage 

near Imlay, just upstream from Rye Patch Reservoir. The ratio 

of annual runoff to effective precipitation volume at this gage 

ranged from less than 0.01 to 0.11 and had a mean of 0.02. 

The low ratio indicates that most of the precipitation in the 

drainage above Imlay was lost to evapotranspiration, either 

from natural vegetation or from irrigated crops or infiltrated 

into the alluvium. The pattern of generally higher ratios of 

runoff to effective precipitation volume during periods of 

above the mean effective precipitation volume and lower ratios 

during periods of below the mean effective precipitation volume was similar to that estimated for the tributary streams.

The effects of ground-water withdrawals on annual runoff 

along the Humboldt River were evaluated using multiple linear 

regressions. Ground-water withdrawals upstream of Palisade 

were not significant to a probability of 0.05 in explaining 

annual runoff at streamflow gages near Carlin or Elko indicating that ground-water withdrawals had little to no effect 

on annual runoff upstream of Carlin. Only annual runoff at 

the streamflow gage near Carlin was significant in predicting 

annual runoff at Palisade. This indicates that ground-water 

withdrawals and mine discharge to Maggie Creek had no 

effect on runoff at Palisade, which is consistent with graphical 

methods that indicated no change in the difference in annual 

runoff between the Carlin and Palisade streamflow gages during 1950–99.

Summary and Conclusions 55
The reach between Palisade and Comus was divided into 

two periods (1955–91 and 1992–99) because ground-water 

withdrawals from two mines discharged directly into the river 

beginning in 1992 and the discharge to the river was correlated 

to the increase in ground-water withdrawals. Ground-water 

withdrawals during 1955–91 had little to no effect on annual 

runoff at Comus; however, the discharge of water to the river 

by the mines during 1992–99 was significant to a probability 

of less than 0.01 indicating that the discharges from the mines 

had the effect of increasing annual runoff at Comus.

Finally, ground-water withdrawals in the reach between 

Comus and Imlay were significant to a probability of 0.04 for 

the 1955–99 period. The negative coefficient suggests that 

ground-water withdrawals may have caused a decrease in the 

annual runoff at Imlay, particularly between 1970 and 1998 

when withdrawals increased six fold. Most of the groundwater withdrawals in the reach between Comus and Imlay 

were for agricultural irrigation located either near the mouths 

of alluvial valleys adjacent to the Humboldt River Valley or 

they were within the valley proper. This contrasts with groundwater withdrawals upstream of the Comus gage where most 

of the ground-water withdrawals were in alluvial basins or 

mountains distant from the river.

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References Cited 57
58 
BACK COVER: Photographs of Humboldt River at T-S Ranch bridge near Argenta, Nevada, downstream of 

streamflow gage at Palisade. Top photograph is from the bridge looking downstream on June 8, 1999 during 

high flow. Bottom photograph is from the bridge looking downstream on October 19, 1992 during a period of 

no flow. Top photograph taken by D.E. Prudic, and bottom photograph taken by D.K. Maurer, U.S. Geological 

Survey.
Prudic and others—Trends in Streamflow on the Humboldt River between Elko and Imlay, Nevada, 1950–99—USGS SIR 2005-5199