U.S. Department of the Interior

U.S. Geological Survey

USGS Fact Sheet 029-99

October 1999

Nevada

The motto of the U.S. Geological

Survey (USGS) “science for a

changing world,” describes the work

of the USGS in Nevada, where the

Federal earth-science agency has

been monitoring or recording elements of change for more than 100

years.

During the 1990’s, Nevada has had

the fastest growing population in the

Nation, with a 40 percent increase

(fig. 1), compared to the national

average of about 8 percent. Most of

this growth has been in southern

Nevada, where the Las Vegas metropolitan area is among the fastest

growing in the Nation. This rapid

growth affects the land, environment,

animal and plant habitats, and water

resources. Although most of the land

is rural, most of Nevada’s population

is urban.

Most of the State’s scarce water

resources are fully appropriated.

Population growth, wildlife-habitat

maintenance, and a 6-year drought

are some factors that have caused a

change in water use. Irrigation is still

the largest use of water in Nevada,

amounting to more than 70 percent of

all withdrawals. Since 1985, however,

the amount of water used for public

supply has increased from 8 percent

of all withdrawals to 20 percent, and

water use in mining has increased

from less than 1 percent to 4 percent.

Collection, analysis, and interpretation of earth science and biological

information by the USGS are significant contributions to sound planning.

The USGS works with more than 40

local, State, and Federal agencies and

Indian Tribes in Nevada to provide

natural-resources information for

immediate and long-term decisions.

Information about USGS programs in

Nevada can be found on the World

Wide Web at http://nevada.usgs.gov/.

Southern Nevada

The rapid population growth in

southern Nevada adds approximately

4,000 people per month to the Las

Vegas Valley. The USGS is using new

technology to support mapping and

geologic, hydrologic, and geophysical

investigations of several southern

Nevada areas.

Studies by USGS geophysicists have

located large regional-scale crustal

structures in southern Nevada that

control the movement of ground

water—sometimes as a conduit and

sometimes as a barrier. The Las Vegas

Valley shear zone (fig. 2) is a prominent structure that bends topography

and geology, separating aquifers from

areas north of the Las Vegas Valley

from those in the valley. The Las

Vegas Valley shear zone is a barrier to

ground-water flow from the north and

is a conduit for water from the Spring

Mountains.

USGS digital earth-science information is addressing environmental

issues and hazards along the lower

Colorado River, including the Lake

Mead National Recreation Area.

USGS maps will provide information

to millions of visitors about geology,

land use, and water resources important to this scenic area. Information

about these studies can be found at

http://geology.wr.usgs.gov/docs/

stateinfo/NV.html.

Figure 1. State and Nation population increases. Clockwise from upper left:

Irrigated lands in Carson Valley, Death Valley area, Stillwater National Wildlife

Refuge, Lahontan cutthroat trout.

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

UNITED STATES POPULATION, IN MILLIONS

1920 1930 1940 1950 1960 1970 1980 1990 2000

NEVADA POPULATION, IN MILLIONS

Nevada

United States

Nevada

300

400

500

600

700

800

900

1,000

200

100

0

United States
science for a changing world

are providing information about

habitat, reproduction, movement, and

survival. In Piute and Eldorado

Valleys, researchers are developing

methods to estimate population

densities, and are x-raying female

tortoises to determine frequency of

reproduction and egg clutch size.

The U.S. Department of Energy

(USDOE) has sponsored desert

tortoise studies in Rock Valley on the

Nevada Test Site (NTS) since the

early 1960’s. The USGS and USDOE

are continuing these long-term

growth studies, which provide the

most complete records of knownaged tortoises, some of which are at

least 37 years old.

Nevada Test Site and Death Valley

At the request of the USDOE, the

USGS is studying the hydrologic and

geologic effects of activities at the

NTS, where more than 900 nuclear

tests were detonated between 1951

and 1992. These cooperative studies

are providing important information

about the potential hazards for

radionuclides and other contaminants

to be transported in regional aquifers

to off-site areas of water use. Regional ground-water systems of

eastern Nevada flow from recharge

areas in the north to discharge areas

in the south, such as Death Valley and

the Colorado River. USGS scientists

are modeling the Death Valley

ground-water flow system to provide

more information to decisionmakers

regarding the effects of Yucca Mountain and Nevada Test Site activities.

Information from these studies can be

found on the World Wide Web at

http://nevada.usgs.gov/doe_nv/.

In the southern part of the Death

Valley flow system, the Ash Meadows National Wildlife Refuge is

home to three federally listed endangered fishes and one federally listed

aquatic insect. These species have

The National Cooperative Geologic

Mapping Program performs geologic

mapping in cooperation with the

Nevada Bureau of Mines and Geology in several parts of Nevada. The

STATEMAP component focuses on

geologic hazards (primarily earthquakes, floods, and ground conditions

affecting construction) in urban and

suburban areas of southern Nevada

and on mineral resource exploration

and environmental protection elsewhere. The FEDMAP component has

focused on geologic hazards of

southern Nevada, and EDMAP has

helped train geologic mappers at

several universities.

The National Earthquake Hazards

Reduction Program, which involves

the USGS as well as Federal Emergency Management Agency, National

Science Foundation, and National

Institute of Standards and Technology, supports earthquake research,

data collection, mitigation, and

emergency preparedness in Nevada,

the third most seismically active State

in the Nation.

Las Vegas Wash

Las Vegas Wash transports urban

runoff and treated sewage effluent

from Las Vegas Valley into Lake

Mead on the Colorado River. Lake

Mead is the primary drinking water

resource for the Las Vegas Valley and

other southwestern metropolitan

areas. Studies by the USGS found

that concentrations of pesticides and

organic compounds in bottom sediment from the Las Vegas Wash were

greater than average values of concentrations at National Water-Quality

Assessment sites throughout the

United States. Investigations in other

areas have linked some of these

compounds to endocrine disruption,

which has been identified in carp

from Las Vegas Wash. Research is

continuing on the sources, fate, and

potential ecological and health effects

of these compounds. A summary of

these initial findings is on the World

Wide Web at http://water.usgs.gov/

lookup/get?circ1170.

Desert Tortoise

The desert tortoise, a threatened

species in the Mojave Desert of

southern Nevada, is being studied in

Piute, Eldorado, and Bird Spring

Valleys by the USGS, in cooperation

with the University of Nevada, Reno.

Researchers are tracking tortoise

movements to understand how

urbanization and relocation practices

affect tortoises and their habitat.

About 1,500 tortoises have been

relocated west of Jean—160 equipped

with radio transmitters to track their

location and survival. In Bird Spring

Valley, 120 tortoises with transmitters

MT. CHARLESTON GASS PEAK FRENCHMAN

MTN

LAS VEGAS

VALLEY

Henderson

Las Vegas

 Valley Shear

 Zone

Unrestricted ground-water flow

MT. CHARLESTON GASS PEAK FRENCHMAN

MTN

TOPOGRAPHY

CENOZOIC DEPOSITS REMOVED

N

Las Vegas

 Valley Shear

 Zone

Las Vegas

Valley Shear

 Zone

Las Vegas

 Valley Shear

 Zone

Las Vegas

 Valley Shear

 Zone

Las Vegas

 Valley Shear

 Zone

Restricted ground-water flow

Figure 2. Geophysics exposes

structure underlying the Las Vegas

Valley. Younger deposits shown in

light green in the upper view are

removed in the lower view to show

complex topography underneath.
Nevada

decreased in number and distribution

because their aquatic environment has

been greatly altered and invaded by

nonnative fishes. The USGS is

studying habitat use and life history

of the endangered fishes and their

interaction with nonnative fishes. The

U.S. Fish and Wildlife Service

(USFWS) is using this information to

restore stream habitat on the Ash

Meadows National Wildlife Refuge.

Western Nevada

The Truckee-Carson-Pyramid Lake

Water Rights Settlement Act contains

many requirements for Department of

the Interior (DOI) agencies. The

USGS is providing detailed waterresources data and river-basin simulation models for use in negotiating the

Truckee River Operating Agreement,

which will be critical to the successful implementation of the Settlement

Act.

Listed as a federally endangered

species in 1967, the cui-ui lake sucker

is endemic to Pyramid Lake and is

important to the current economy and

traditional culture of Paiute Indians at

the Pyramid Lake Reservation. Waste

discharges to and water diversions

from the Truckee River since the late

1800’s have disrupted the spawning

habitat in the river above Pyramid

Lake. In an attempt to revitalize the

Pyramid Lake fishery, the Marble

Bluff Fish Passage Facility was

completed in 1976 to bypass the

Truckee River Delta. The facility has

met with only partial success. USGS

models of cui-ui population responses

to Truckee River flows are supporting

development of a revised Cui-ui

Recovery Plan.

Sierra Nevada

Lake Tahoe is renowned for its high

alpine setting and deep, clear waters.

Recognizing these attributes, President Clinton signed an Executive

Order in July 1997 directing Federal

agencies to establish a formal interagency partnership to assure coordination and efficient management of

federal activities within the Lake

Tahoe Basin.

Human activity has accelerated the

decline in clarity and quality of this

once pristine lake. Since 1979, the

USGS has been involved in waterquality sampling of streams in the

Lake Tahoe Basin. As part of this

cooperative effort with several

agencies, streams are monitored for

suspended-sediment and nutrient

contributions to the Lake. In 1990,

the USGS began monitoring groundwater flow in the basin.

USGS efforts in response to the July

1997 Presidential Order include

sampling water for methyl tert-butyl

ether (MTBE) and other gasoline

additives. The USGS has twice

sampled several locations in the lake

at differing depths, as well as tributary streams and other alpine lakes in

the Tahoe basin. Both times, the

USGS found compounds related to

gasoline byproducts in all samples

from Lake Tahoe and adjacent lakes.

Another effort related to the Presidential Order was updating the bathymetry of Lake Tahoe. Recent advances

in marine sonar capabilities allow

mapping the bathymetry of large

underwater areas. The USGS used

this advanced technology on Lake

Tahoe in the summer of 1998 (fig. 3).

The two types of maps that resulted

provide the multidisciplinary Lake

Tahoe research community a dataset

upon which to build their studies.

Information on activities from the

Federal partnerships for Lake Tahoe

is available at the Lake Tahoe Information Clearinghouse on the World

Wide Web at http://tahoe.usgs.gov/.

Lahontan Cutthroat Trout

Once widespread in streams and lakes

of the Great Basin, the range of

Lahontan cutthroat trout (LCT) has

decreased due to habitat destruction

and introduction of nonnative fishes.

The current stream habitat supports

10 percent of the LCT former range,

and in lakes, LCT occupy less than 1

percent of their former range.

Only two self-sustaining LCT lake

populations persist in their native

habitats, the Summit Lake LCT in the

Quinn River/Black Rock Desert

subbasin in Nevada and the Independence Lake LCT in the Truckee River

basin in California. The Summit Lake

LCT represent the healthiest and most

stable population whereas the Independence Lake LCT have been near

extinction for the past 25 years.

USGS scientists are researching those

factors most influential in LCT

population dynamics. Information

gained from this research is intended

to provide the USFWS and others

with guidance for enhancing survival

and recovery of LCT.

Figure 3. An exaggerated perspective

view of a large failure ofthe Lake

Tahoe lake margin. The view is from

the east, looking west toward

McKinney Bay near Tahoe City, Calif.

The land is gray, the lake floor is

colored (blue the deepest), and areas

that have not been surveyed. are

black. A debris tongue, shown in green

and at the center of the view, is 4.5

miles wide and 5.6 miles long.
Printed on recycled paper

USGS office locations USGS State Representative

The USGS has 191 

employees in Nevada

Carson

 City

Elko

Las Vegas

Reno

Mercury

333 West Nye Lane, Rm 203

Carson City, NV 89706

Telephone: (775) 887-7600

Fax: (775) 887-7629

USGS Home Page

http://www.usgs.gov

http://nevada.usgs.gov

Reports and products

1-888-ASK-USGS

Northern Nevada

The Humboldt River Basin includes

many of the Nation’s largest gold

deposits. Open pit gold mines tapping

the Carlin and Battle Mountain ore

bodies are some of the richest in the

world. Dewatering these pits to allow

deep mining has resulted in major

interbasin water transfers, and

disposal of the water has doubled the

base flow of the Humboldt River.

Concerns of the Bureau of Land

Management (BLM), the USFWS,

and the State about the long-term

cumulative effects of this regionalscale dewatering formed the basis for

a cooperative Humboldt River Basin

Water Resources Assessment with the

USGS. During the first phase of this

study, historical trends in groundwater levels were documented and

water budgets were estimated for

valleys in the middle Humboldt River

basin. The USGS work on the second

phase began in 1999, and includes

modeling regional ground- and

surface-water resources. Information

about USGS work in the Humboldt

River Basin is on the World Wide

Web at http://nevada.usgs.gov/humb/.

The USGS is assessing mineral

deposits in the Humboldt River basin.

The USGS, in cooperation with the

BLM, is mapping the environmental

signatures of mineral deposits to

provide important long-term land-use

planning information. Data from the

Nevada Gold Project, a study of the

origin of precious metal deposits, is

intended to enhance the assessment.

The USGS, in cooperation with the

Mackay School of Mines, the mining

industry, and the Nevada Bureau of

Mines and Geology is modeling gold

deposits, including those along the

Carlin ore body, which contributes

more than 35 percent of the total

annual gold production of the United

States. Preliminary results of the gold

project studies are available on the

World Wide Web at http://

caldera.wr.usgs.gov/OF98-338/.

Statewide Mapping

The USGS completed coverage of

digital raster graphics for the State

from the 1:24,000-scale topographic

maps. These maps depict lakes and

streams, highways and railroads,

boundaries, and geographic names.

Contour lines depict altitude and

shape of terrain. Nevada is covered

by 1,991 maps at this scale, which are

useful for civil engineering, land-use

planning, natural-resource monitoring, and other technical and scientific

applications. These maps are favorites with the public for outdoor uses,

including hiking, camping, and

backcountry hunting and fishing.

The USGS also completed Digital

Elevation Model (DEM) coverage for

Nevada. The DEM’s are digital files

of terrain altitudes for ground positions at regularly spaced horizontal

intervals. DEM data correspond to

the USGS 7.5-minute topographic

quadrangle map series. The DEM’s

can be used to create maps with

three-dimensional perspectives of the

landscape to assess slope and location

for vegetation and habitat mapping,

hydrologic modeling for flood

analysis, and hazard mitigation.

The USGS, under the DOI High

Priority Base Data Program and in

cooperation with the Natural Resources Conservation Service and

Farm Service Agency, is producing

Digital Orthophoto Quadrangles

(DOQ’s; fig. 4). The DOQ’s are

scanned aerial photographs with

distortion and displacement removed.

The DOQ’s can be used for updating

land-use and land-cover maps,

natural-resource inventory and

mapping, and delineating boundaries.

Figure 4. Availability of digital

orthophoto quadrangles (DOQ’s) for

Nevada.

37°

38°

36°

42°

120° 119° 118° 117°

39°

41°

40°

35°

116° 115° 114°

DOQ Available

DOQ Authorized

DOQ Planned

Humbolt Basin DOI DOQ's Completed