Nevada Test Site

Environmental Report Summary 2007

DOE/NV/25946--543-SUM

Vision • Service • Partnership

National Security TechnologiesLLC

Schooner Crater

September 2008
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The information presented in this document is explained in greater detail in the Nevada Test Site Environmental Report 

2007 (DOE/NV/25946--543). A compact disc of this document is included on the back inside cover. This 

document can also be downloaded from the National Nuclear Security Administration Nevada Site Office at 

http://www.nv.doe.gov/library/publications/environmental.aspx.

For more information about the Nevada Test Site’s Environmental Report, contact Bruce Hurley at 

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This report was prepared for: 

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1

Nevada Test Site 

Environmental Report Summary 2007

The U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office (NNSA/NSO) directs 

the management and operation of the Nevada Test Site (NTS). The NTS is the nation’s historical testing site for 

nuclear weapons from 1951 through 1992 and is currently the nation’s unique site for ongoing national-securityrelated missions and high-risk operations. NNSA/NSO strives to provide to the public an understanding of the 

current activities on the NTS, including environmental monitoring and compliance activities aimed at protecting the 

public and the environment from radiation hazards and from nonradiological impacts. This document is a summary 

of the Nevada Test Site Environmental Report (NTSER) for calendar year 2007 (see attached compact disc on 

inside back cover). The NTSER is a comprehensive report of environmental activities performed at the NTS and 

offsite facilities over the previous calendar year. It is prepared annually to meet the requirements and guidelines of 

the U.S. Department of Energy (DOE) and the information needs of NNSA/NSO stakeholders. To provide an 

abbreviated and more readable version of the NTSER, this summary report is produced. This summary does not 

include detailed data tables, monitoring methods or design, a description of the NTS environment, or a discussion of 

all environmental program activities performed throughout the year. The reader may obtain a hard copy of the full 

NTSER as directed on the inside front cover of this summary report. 

The NTS is located about 65 miles northwest of Las Vegas. The approximately 1,375-square mile site is one of the 

largest restricted access areas in the United States. It is surrounded by federal installations with strictly controlled 

access as well as by lands that are open to public entry.
2

NTS History

Between 1940 and 1950, the area now known as the NTS was part 

of the Las Vegas Bombing and Gunnery Range. In 1950, the NTS 

was established as the primary location for testing the nation’s nuclear 

explosive devices. Such testing took place from 1951 to 1992. 

Tests conducted through the 1950s were predominantly atmospheric 

tests. These involved a nuclear explosive device detonated while 

on the ground surface, on a steel tower, suspended from tethered 

balloons, dropped from an aircraft, or placed on a rocket. Several 

tests were categorized as “safety experiments” and “storagetransportation tests,” involving the destruction of a nuclear device 

with non-nuclear explosives. Some of these tests resulted in 

dispersion of plutonium in the test vicinity. One of these test areas, 

Project 57, lies just north of the NTS boundary on the Nevada 

Test and Training Range (NTTR). Other tests, involving storagetransportation, were conducted at the north end of the NTTR 

(Double Tracks) and on the Tonopah Test Range (TTR) (Clean Slates 

I, II, and III). All nuclear device tests are listed in United States Nuclear 

Tests, July 1945 through September 1992.

1

The first underground test, a cratering test, was conducted in 1951. 

The first totally contained underground test was in 1957. Testing was 

discontinued during a moratorium that began October 31, 1958, but 

was resumed in September 1961 after tests by the Union of Soviet 

Socialist Republics began. Since late 1962, nearly all tests have been 

conducted in sealed vertical shafts drilled into Yucca Flat and Pahute 

Mesa or in horizontal tunnels mined into Rainier Mesa. From 1951 to 

1992, a total of 828 underground nuclear tests were conducted at the 

NTS. Approximately one-third of these tests was detonated near or 

below the water table. 

Five earth-cratering (shallow-burial) tests were conducted over the 

period of 1962 through 1968 as part of the Plowshare Program that 

explored peaceful uses of nuclear explosives. The first and highest 

yield Plowshare crater test, Sedan, was detonated at the northern end 

of Yucca Flat on the NTS. The second-highest yield crater test was 

Schooner, located in the northwest corner of the NTS. Mixed fission 

products, tritium, and plutonium from these tests were entrained 

in the soil, ejected from the craters, and deposited on the ground 

surrounding the craters.

Other nuclear-related experiments at the NTS included the Bare 

Reactor Experiment-Nevada series in the 1960s. These tests were 

performed with a 14-million electron volt neutron generator mounted 

on a 1,527-foot steel tower used to conduct neutron and gammaray interaction studies on various materials and assess radiation 

doses experienced by the nuclear bomb survivors of Hiroshima and 

Nagasaki. In addition, from 1959 through 1973 a series of open-air 

nuclear reactor, nuclear engine, and nuclear furnace tests were conducted in Area 25, and a series of tests with a 

nuclear ramjet engine was conducted in Area 26. The test released mostly gaseous radioactivity (radio-iodines, 

radio-xenons, radio-kryptons) and some fuel particles due to erosion of the metal cladding on the reactor fuel; 

these releases resulted in negligible deposition on the ground.

1 U.S. Department of Energy, 2000. Report No. DOE/NV--209 (Rev. 15).

NTS - Continental Test Site

After the end of World War II, the United 

States tested nuclear weapons at Bikini Atoll 

and Enewetak in the Marshall Islands of the 

Central Pacific. 

In June 1950, with the outbreak of hostilities 

in Korea and U.S. relations with the Soviet 

Union continuing to deteriorate, the search 

began for a continental test site to overcome 

the difficulties with remoteness and security 

experienced with testing in the Pacific. The 

final choices included Dugway Proving 

Ground–Wendover Bombing Range in 

western Utah, Alamagordo-White Sands 

Guided Missile Range in south central New 

Mexico, and a North Site and a South Site 

on the Las Vegas Bombing and Gunnery 

Range in southern Nevada. 

On December 18, 1950, President Truman 

approved the recommendations of Los 

Alamos testing officials and the Atomic 

Energy Commission, christening the 

South Site on the Las Vegas Bombing and 

Gunnery Range as the nation’s continental 

test site. It is called the Nevada Proving 

Ground. 

On Saturday, January 27, 1951, an Air Force 

B-50D bomber dropped a 1-kiloton yield 

nuclear bomb over Frenchman Flat. It was 

the world’s tenth nuclear detonation and was 

the first NTS test. 

On September 23, 1992, the last underground 

nuclear test was conducted on the NTS after 

which Congress imposed a moratorium on 

nuclear weapons testing. 

Since 1951, a total of 100 atmospheric and 

828 underground nuclear weapons tests 

were conducted at the NTS.

Source: T. R. Fehner and F. G. Gosling, 2000. Origins of the Nevada 

Test Site, DOE/MA-0518, History Division, Executive Secretariat, 

Management and Administration, U.S. Department of Energy.
3

Historic Nuclear Testing Areas
4

The NTS Now

Los Alamos, Lawrence Livermore, and Sandia 

National Laboratories are the principal organizations 

that sponsor and implement experimental programs 

at the NTS. The three major NTS missions include 

National Security, Environmental Management, 

and Stewardship of the NTS. During the conduct 

of all missions and their programs, NNSA/NSO 

complies with applicable environmental and public 

health protection regulations and strives to manage 

the land and facilities at the NTS as a unique and 

valuable national resource. In 2007, National Security 

Technologies, LLC (NSTec), was the Management 

and Operations contractor accountable for the 

successful execution of work and ensuring that work 

was performed in compliance with environmental 

regulations.

NTS activities in 2007 continued to be diverse, with 

the primary goal being to ensure that the existing 

U.S. stockpile of nuclear weapons remains safe and 

reliable. Facilities that support this mission include 

the U1a Facility, the Big Explosives Experimental 

Facility (BEEF), the Device Assembly Facility (DAF), 

and the Joint Actinide Shock Physics Experimental 

Research (JASPER) Facility. Facilities that support 

the Homeland Security program include the new 

Radiological/Nuclear Countermeasures Test and 

Evaluation Complex (Rad/NucCTEC), which was 

expected to be operational in October 2006, but is 

currently on hold. Facilities that support the Waste 

NTS Missions and Their Programs

National Security

Stockpile Stewardship Program – Conducts highhazard operations in support of defense-related nuclear 

and national security experiments. 

Homeland Security Program – Provides support 

facilities, training facilities, and capabilities for 

government agencies involved in counterterrorism 

activities, emergency response, first responders, national 

security technology development, and nonproliferation 

technology development. 

Test Readiness Program – Maintains the capability 

to resume underground nuclear weapons testing, if 

directed. 

Environmental Management

Environmental Restoration Program – Characterizes 

and remediates the environmental legacy of nuclear 

weapons and other testing at the NTS and offsite 

locations and develops and deploys technologies that 

enhance environmental restoration. 

Waste Management Program – Manages and safely 

disposes of low-level waste received from DOEand U.S. Department of Defense-approved facilities 

throughout the United States and mixed low-level 

waste generated in Nevada by NNSA/NSO, and safely 

manages and characterizes hazardous and transuranic 

wastes for offsite disposal.

Stewardship of the NTS

Facilities and Infrastructure – Maintains the 

buildings, roads, utilities, and facilities required to 

support all NTS programs and to provide a safe 

environment for NTS workers.

Management Program include the Area 5 Radioactive 

Waste Management Complex (RWMC) and the Area 3 

Radioactive Waste Management Site (RWMS). Other 

NTS activities include demilitarization activities; 

controlled spills of hazardous material at the NonProliferation Test and Evaluation Complex (NPTEC) 

(formerly known as the Hazardous Materials Spill 

Center); remediation of industrial sites; processing 

of waste destined for the Waste Isolation Pilot Plant 

in Carlsbad, New Mexico, or the Idaho National 

Laboratory in Idaho Falls, Idaho; disposal of radioactive 

and mixed waste; and environmental research.
5

The Legacy of NTS Nuclear Testing

Approximately one-third of the 828 underground 

nuclear tests on the NTS were detonated near or 

below the water table resulting in the contamination 

of groundwater in some areas. In addition, the 100 

atmospheric nuclear tests conducted on the NTS and 

numerous nuclear-related experiments resulted in the 

contamination of surface soils, materials, equipment, 

and structures, mainly on the NTS. The NNSA/NSO 

Environmental Management Mission was established 

to address this legacy of contamination. Within 

Environmental Management, the Environmental 

Restoration Project is responsible for remediating 

contaminated sites, and the Waste Management Project 

is responsible for safely managing and disposing 

radioactive waste.

The primary regulatory driver of the Environmental 

Restoration Project is the Federal Facility Agreement 

and Consent Order (FFACO) between the State of 

Nevada, DOE, and U.S. Department of Defense. The 

FFACO identifies Corrective Action Units (CAUs), 

which are groupings of Corrective Action Sites 

(CASs) that delineate and define areas of concern for 

contamination. Approximately 2,800 CASs have been 

identified, many of which have already been remediated 

and/or closed. The public is kept informed of 

Environmental Management activities through periodic 

newsletters, exhibits, and fact sheets, and Environmental 

Management provides the opportunity for public input 

via the Community Advisory Board consisting of

15–20 citizen volunteers from Nevada. 

Areas of Soil Contamination on and off the NTS

Legacy Contamination

Groundwater – Areas of known and potential 

groundwater contamination on the NTS due to 

underground nuclear testing are called Underground 

Test Area (UGTA) Corrective Action Units. It is 

estimated that 300 million curies (Ci) of radiation 

were released underground during 828 nuclear tests. 

The total amount of radiation deposited below the 

groundwater table is approximately 60 million Ci, 

based on the last decay-corrected calculation from 

1992. Since there is no feasible technology available 

that would allow for the cleanup of deep, extensive 

groundwater contamination, the strategy of the 

Environmental Management Program is to identify 

contaminant boundaries and implement an effective 

long-term monitoring system. 

Soil – Radioactively contaminated surface soils 

directly resulting from nuclear weapons testing occur 

at approximately 100 sites on and around the NTS. 

Closure of these sites is conducted in accordance with 

the Federal Facility Agreement and Consent Order 

(FFACO) and upon approval of the State of Nevada. 

Corrective actions required to complete closure 

range from removal of soil to closure in place with 

restricted access controls, such as fencing and posting.

Air – Airborne radioactive contamination from the 

resuspension of contaminated soils at legacy sites and 

from current activities (such as waste management) 

is monitored continuously on and off the NTS. 

Since the cessation of atmospheric nuclear testing, 

the annual amounts of radiation released into the air 

from the NTS have ranged from 48 to 2,200 Ci for 

tritium, 0.0018 to 0.40 Ci for plutonium, and 0.039 to 

0.049 Ci for americium. These emissions cannot be 

distinguished from the background airborne radiation 

measured in communities surrounding the NTS. 

Structures/Materials – There are approximately 

1,850 sites where facilities, equipment, structures, 

and/or debris were contaminated by historic nuclear 

research, development, and testing activities. The 

responsibility for remediating these Industrial Sites 

belongs to the Environmental Restoration Project. As 

of May 30, 2008, 1,717 sites have been approved for 

final completion in accordance with the FFACO and 

approved by the State of Nevada.

Waste Disposal – Low-level and mixed low-level 

radioactive waste have been generated by historic 

nuclear research, development and testing activities, 

and the resulting environmental cleanup activities. 

More than 1.33 million cubic yards of this waste 

have been safely disposed at the Area 3 and Area 5 

Radioactive Waste Management Sites as of December 

30, 2007. The estimated total amount of radioactivity 

at the time of disposal was 13.5 million Ci. The 

radioactive content of the disposed waste decays over 

time at a varied rate depending on the radionuclide.
6

Areas of Potential Groundwater Contamination on the NTS 
7

Potential Sources of Radiological Air Emissions on the NTS
8

Understanding Radiation

Radiation is energy that travels through matter or 

space in the form of waves or high-speed particles. 

Light, heat, and sound are types of radiation. Ionizing 

radiation is a very high-energy form of electromagnetic 

radiation. Ionizing radiation are particles or rays given 

off by unstable atoms as they are converted, or decay, 

into more stable atoms. Ionizing radiation may be 

found everywhere. Almost all exposure to ionizing 

radiation comes from natural sources (82 percent in the 

United States). These sources include cosmic radiation 

from outer space, terrestrial radiation from materials 

like uranium and radium in the earth, and naturally 

occurring radioactive elements (i.e., radionuclides) in 

Forms of Radiation

Alpha particles are heavy, positively charged particles given off by some decaying atoms. Alpha particles can 

be blocked by a sheet of paper. Atoms emitting alpha particles are hazardous only if they are swallowed or 

inhaled. 

Beta particles are electrons or positrons (positively charged electrons) ejected from the nucleus of a decaying 

atom. More penetrating than alpha radiation, beta particles can pass through several millimeters of skin. A 

sheet of aluminum only a fraction of an inch thick will stop beta radiation. Beta particles can damage skin, 

but are most hazardous if the beta-emitting atoms are swallowed or inhaled. 

Gamma rays are waves of pure energy similar to X-rays, light, microwaves, and radio waves. Gamma rays 

are emitted by certain radionuclides when their nuclei transition from a higher to a lower energy state. 

They can readily pass into the human body. They can be almost completely blocked by about 40 inches 

of concrete, 40 feet of water, or a few inches of lead. Gamma rays can be both an external and internal 

hazard. 

X-rays are a more familiar form of electromagnetic radiation, usually with a limited penetrating power, 

typically used in medical or dental examinations. Television sets, especially color, give off soft (low-energy) 

X-rays; thus, they are shielded to greatly reduce the risk of radiation exposure. 

Neutrons are uncharged heavy particles contained in the nucleus of every atom heavier than ordinary 

hydrogen. They induce ionization only indirectly in atoms which they strike, but can damage body tissues. 

Neutrons are released, for example, during the fission (splitting) of uranium atoms in the fuel of nuclear 

power plants. They can also be very penetrating. In general, efficient shielding against neutrons can be

provided by materials containing hydrogen, such as water. Like gamma rays, neutrons are both an external 

and internal hazard. 

Understanding Radiation Dose

Dose is a generic term to describe the amount of 

radiation a person receives. The energy deposited 

indicates the number of molecules disrupted. The 

energy the radiation deposits in tissue is called the 

absorbed dose. The units of measure of absorbed 

dose are the rad or the gray. The biological effect 

of radiation depends on the type of radiation (alpha, 

beta, gamma, or X-ray) and the tissues exposed. A 

measure of the biologic risk of the energy deposited is 

the dose equivalent. The units of dose equivalent are 

called rems or sieverts. In this report, the term dose 

is used to mean dose equivalent measured in rems. A 

thousandth of a rem is called a millirem, abbreviated as 

mrem. An average person in the United States receives 

about 300 mrem each year from natural sources and an 

additional 60 mrem from medical procedures, consumer 

products, and activities. Whether or not there is a 

“safe” radiation dose equivalent is a controversial 

subject. Because the topic has yet to be settled 

scientifically, regulators take a conservative approach 

and assume that there is no such thing as a 100 percent 

safe dose equivalent, and it is assumed that the risk of 

our food, water, and the aerosols and gases in the air 

we breathe. Exposures to man-made radiation in our 

everyday life come from smoking cigarettes, traveling 

on airplanes, and having medical X-rays. For the public 

surrounding the NTS, less than 1 percent of their total 

radiation exposure is now attributable to past or current 

NTS activities. 
9

Common Doses to the Public 

Source/Activity Average Dose/Year

(or as noted)

Five-hour jet plane ride 3 mrem

Building materials 4 mrem

Chest X-ray 8 mrem

Cosmic 30 mrem

Soil 35 mrem

Internal to our body 40 mrem

Mammogram 138 mrem

Radon gas 200 mrem

CT scan 2,500 mrem

Smoking 20 cigarettes/day 5,300 mrem to a smoker’s lung

One cancer treatment 5,000,000 mrem to the tumor

Source: <http://hss.energy.gov/HealthSafety/WSHP/radiation/Radiation-final-6-20.pdf>,

accessed on 6/26/2008 

Radionuclides Detected on the NTS

Name* Abbreviation

Primary Type(s) of 

Radiation Major NTS Source

Man-Made

Americium-241 241Am Alpha, gamma

In soil at and near legacy sites of aboveground nuclear testing. 

Detected in soil and air.

Cesium-137 137Cs Beta, gamma 

Plutonium-238 238Pu Alpha 

Strontium-90 90Sr Beta

Plutonium239+240

239+240Pu Alpha In soil at and near legacy sites of plutonium dispersal experiments. 

Detected in soil and air.

Tritium 3

H Beta In groundwater in areas of underground nuclear tests, in surface 

ponds used to contain contaminated groundwater, in soil at nuclear 

test locations, in waste packages buried in pits at waste management 

sites. Detected in groundwater and air.

Naturally Occurring

Be-7 7Be Gamma Produced by interactions between cosmic radiation from the sun and 

the earth’s upper atmosphere. Detected in air.

Potasium-40 40K Beta, gamma

Naturally occurring in the earth’s crust. Detected in groundwater, 

soil, and air.

Radium-226 226Ra Alpha, gamma

Thorium-232 232Th Alpha**

Uranium-234 234U Alpha**

Uranium-235 235 U Alpha, gamma**

Uranium-238 238 U Alpha**

*The number given with the name of the radionuclide is the atomic mass number and is the number of protons and neutrons together in the nucleus of the atom. 

Radionuclides with the same number of protons are the same element and radionuclides of the same element are called isotopes of one another. Plutonium and uranium 

each have several radioactive isotopes that are detected on the NTS.

**These radionuclides decay to other radionuclides (called progeny or daughters) which emit alpha, beta, and gamma radiation. 

}

}

developing an adverse health effect (such as cancer) 

is proportionate to the amount of radiation dose. 

Many human activities increase our exposure to 

radiation over and above the average background 

radiation dose of 300 mrem per year. These 

activities include, for example, uranium mining, 

airline travel, and operating nuclear power plants. 

Regulators balance the benefit of these activities 

to the risk of increasing radiation exposures above 

background, and as a result, set dose limits for the 

public and workers specific to these activities. The 

DOE has set the dose limit to the public from 

exposure to DOE-related nuclear activities to 

100 mrem/yr. This is the same public dose limit 

set by the U.S. Nuclear Regulatory Commission 

(NRC) and recommended by the International 

Commission on Radiological Protection and the 

National Commission on Radiological Protection 

and Measurements. The NRC has set the dose 

limit for radiation workers to 5 rem/yr. There is 

no regulatory standard for radiation dose limits to 

workers or the public across industries, states, or 

countries.
10

Public Dose Limits for NTS Radiation

 10 mrem/yr – This is the dose limit to the public 

(above natural background) from just the air 

transport pathway, as specified by the Clean Air 

Act National Emission Standards for 

Hazardous Air Pollutants (NESHAP). 

 100 mrem/yr – This is the dose limit to the public 

(above natural background) from all possible 

pathways combined, as specified by DOE

Order 5400.5, Radiation Protection of the Public 

and the Environment.

Monitoring NTS Radiation and 

Pathways of Exposure to the Public

The release of man-made radionuclides from the NTS 

has been monitored since the first decade of atmospheric 

testing. After 1962 when nuclear tests were conducted 

only underground, the radiation exposure to the public 

surrounding the NTS was greatly reduced. Underground 

nuclear testing nearly eliminated atmospheric releases 

of radiation, but resulted in the contamination of 

groundwater in some areas of the NTS. After the 1992 

moratorium on nuclear testing, radiation monitoring 

focused on detecting airborne radionuclides that are 

resuspended with historically contaminated soils on 

the NTS and on detecting man-made radionuclides in 

groundwater. 

Potential Dose Pathways to the Public

There are three pathways

in this dry desert 

environment by which 

man-made radionuclides 

from the NTS might 

reach the surrounding 

public: 

Air Transport 

Pathway – Members 

of the public may inhale 

or ingest radionuclides 

that are resuspended by 

the wind from known 

contaminated sites on 

the NTS. However, such 

resuspended radiation 

measured off and on 

the NTS is much lower 

than natural background 

radiation in all areas 

accessible to the public. 

Ingestion Pathway – Members of the public may ingest game animals 

that have been exposed to contaminated soil or water on the NTS, have 

moved off the NTS, and have then been hunted. 

Groundwater Pathway – Drinking contaminated groundwater is currently not a possible pathway for public 

exposure given the restricted public access to the NTS and the location of known contaminated groundwater on the 

NTS. No man-made radionuclides occur in drinking water sources monitored off the NTS, and no drinking water 

wells on the NTS have measurable levels of man-made radionuclides. Only the groundwater from monitoring wells 

drilled near underground tests on the NTS show radioactive contamination. 
11

Estimated 2007 Radiation Dose to the 

Public from NTS Operations

Inhalation – Compliance with radiation dose limits 

to the general public from the air transport pathway is 

demonstrated using air sampling results from six onsite 

“critical receptor” sampling stations. The radionuclides 

detected at three or more of the NTS critical receptor 

samplers were 241Am, 238Pu, 239+240Pu, 233+234U, 235+236U, 238U, and 3

H. The uranium isotopes are attributed to 

naturally occurring uranium. As in previous years, 

the 2007 data from the six critical receptor samplers 

show that the NESHAP dose limit to the public of 

10 mrem/yr was not exceeded. The Schooner critical 

receptor station, in the far northwest corner of the 

NTS, had the highest concentrations of radioactive 

air emissions, yet an individual residing at this station 

would experience a dose from air emissions of only 

1.9 mrem/yr. This annual dose is 19 percent of the 

NESHAP public dose limit. No one resides at this 

location, and the dose at offsite populated locations 

(12 to 50 miles) from the Schooner station would be 

much lower due to wind dispersion.

Ingestion – NTS game animals include pronghorn 

antelope, mule deer, chukar, Gambel’s quail, mourning 

doves, cottontail rabbits, and jackrabbits. Small game 

animals from different contaminated NTS sites are 

trapped each year and analyzed for their radionuclide 

content. These results are used to construct worst-case 

scenarios for the dose to hunters who might consume 

these animals if the animals moved off the NTS. In 

2007, mourning doves were sampled at the E Tunnel 

Ponds. The muscle tissues of a pronghorn antelope 

killed accidentally by a vehicle and of a foal (used as a 

surrogate large game animal) killed by a predator were 

also sampled in 2007. Based on these samples, the 

highest dose to a member of the public was estimated 

to be 0.091 mrem for the person who consumed the 

entire sampled antelope. 

Direct Exposure – No members of the public are 

expected to receive direct gamma radiation from NTS 

operations which is above background levels. Areas 

accessible to the public, such as the main entrance gate, 

2007 Dose to the Public from All Pathways

2.19 mrem/yr – This is the maximum dose to the public from inhalation, ingestion, and direct exposure pathways 

that is attributable to NTS operations. It is well below the dose limit of 100 mrem/yr established by DOE 

Order 5400.5 for radiation exposure to the public from all pathways combined. This total dose estimate 

is indistinguishable from natural background radiation experienced by the public residing in communities 

surrounding the NTS. 

had direct gamma radiation exposure rates comparable 

to natural background rates from cosmic and terrestrial 

radiation. A very small exposure to external radiation 

from a piece of heavy equipment taken off of the NTS 

may have occurred in 2007. A shear machine used for 

demolition projects that contained residual radioactive 

material was taken off of the NTS for 112 days in 2007. 

The estimated maximum dose to a hypothetical individual 

who spent 12 hours per day within 1 foot of the 

radioactive material for all 112 days is less than 0.2 mrem. 

This estimate is extremely conservative (i.e., greater than 

expected), because it is also assumed that the hypothetical 

individual ingested all the removable radioactive material 

that was on the equipment.

Percents of Total Dose to the Public from 

Natural Background Sources and from the NTS

Groundwater — there is no NTS radiation dose to the public from this 

pathway. Annual monitoring continues to 

verify that no contaminated groundwater 

has migrated beyond the NTS boundaries 

into surrounding water supplies used by 

the public
12

Radioactive Air Emissions

NTS radioactive emissions are monitored on site to 

determine the public dose from inhalation (presented 

on page 11) and to ensure compliance with NESHAP 

under the Clean Air Act. A network of 19 air sampling 

stations and a network of 109 thermoluminescent 

dosimeters (TLDs) are located throughout the NTS 

(see map on page 13), mainly within those numbered 

Operational Areas where historic nuclear testing has 

occurred or where current radiological operations occur. 

NTS air sampling stations monitor tritium in water 

vapor, man-made radionuclides, and gross alpha and 

beta radioactivity in airborne particulates. The TLD 

stations monitor direct gamma radiation esposure.

Radioactive emissions are also monitored at stations in 

selected towns and communities within 240 miles of the 

NTS by the independent Community Environmental 

Monitoring Program (CEMP), which is coordinated 

by the Desert Research Institute (DRI) of the Nevada 

System of Higher Education under contract with 

NNSA/NSO. The CEMP can independently confirm 

NTS’s compliance with radiological air emission 

standards. Its purpose is to provide monitoring for 

radionuclides which may be released 

from the NTS. A network of 

29 CEMP stations are used (see

map on page 14). The CEMP 

stations monitor gross alpha and 

beta radioactivity in airborne 

particulates using low-volume 

particulate air samplers, penetrating 

gamma radiation using TLDs, 

gamma radiation exposure rates 

using pressurized ion chamber 

(PIC) detectors, and meteorological 

parameters using automated weather 

instrumentation (MET stations).

Highest Average Concentrations of 

Man-Made Radionuclides in Air Samples on the NTS

Radionuclide

CL (a)

(10-15μCi/mL)

Highest Average

Concentration

(10-15 μCi/mL)(b)

Sampler

Location

241Am 1.9 0.046 Bunker 9-300

3

H 1,500,000 285,320 Schooner

238Pu 2.1 0.0053 Bunker 9-300

239+240Pu 2.0 0.279 Bunker 9-300

(a) Concentration limits established by NESHAP, in microcuries per milliliter (μCi/mL). 

(b) The scale of concentration units for radionuclides shown in the table have been 

standardized to 10-15 μCi/mL. This scale may differ from those reported in detailed 

radionuclide-specific data tables in the NTSER.

Estimated Quantity of Man-Made Radionuclides

Released into the Air from the NTS in 2007

(in Curies)

Tritium

(3H)

Plutonium 

(238Pu)

Plutonium 

(239+240Pu)

Americium

(241Am)

550 0.054 0.32 0.047

Plutonium and americium sources are legacy sites of past nuclear testing on the NTS where 

these radionuclides are in surface soils that can become re-suspended by wind.

Concentration of Man-Made Radionuclides – 

Several man-made radionuclides were detected at NTS 

air sampling stations in 2007: 241Am, 3

H, 238Pu, and 239+240Pu. None, however, exceeded concentration 

limits established by the Clean Air Act. The highest 

average level of 241Am, 238Pu, and 239+240Pu was detected 

at Bunker 9-300 in Area 9, located within an area of 

known soil contamination from past nuclear tests. 

The highest average level of tritium was detected at 

Schooner, site of the second-highest yield Plowshare 

cratering experiment on the NTS where tritium-infused 

ejecta surrounds the crater.

No man-made radionuclides were detected above 

minimum detectable concentrations in the air samples 

from the JASPER Facility, and no 

radiological releases occurred at 

U1a, BEEF, or DAF. 

No airborne radioactivity related 

to any NTS operations was 

detected in any of the CEMP 

samples during 2007. No 

man-made gamma-emitting 

radionuclides were detected. 

Naturally occurring radioactive 

beryllium (7

Be) was detected in 

most air particulate samples. 

Total Quantity of Man-Made 

Radionuclides – The total 

amounts (measured in Ci) of manmade radionuclides that were emitted to the air from 

all sources on the NTS in 2007 was estimated to be 

550 Ci for tritium, 0.047 Ci for 241Am, 0.054 Ci for 238Pu, 

and 0.32 Ci for 239+240Pu. These amounts are similar to 

those from previous years. Over the past 10 years, total 

emissions have ranged from 160 to 564 Ci for tritium, 

0.039 to 0.049 Ci for americium, and 0.24 to 0.39 Ci for 

239+240Pu.
13

2007 NTS Air Sampling Network
14

Gamma Radiation Exposure – Ten of the NTS 

TLD stations are located where radiation effects from 

NTS operations are negligible, and therefore measure 

only natural background levels of gamma radiation from 

cosmic and terrestrial sources. In 2007, the mean 

measured background level from the ten stations was 

121 mR/yr. This is well within average background levels 

observed in other parts of the U.S. of similar elevation 

above sea level. Background radiation varies not only 

by elevation but by the amounts of natural radioactive 

materials in soil and rock in different geographic regions. 

The highest estimated mean annual gamma 

exposure measured at a TLD station on the NTS was 

750 mR/yr at Schooner, one of the legacy Plowshare sites 

on Pahute Mesa. The lowest was 61 mR/yr in Mercury 

at the fitness track. The mean annual gamma exposure 

at 17 TLD locations near the Area 3 and Area 5 RWMSs 

was 147 mR. At the 35 TLD locations near known legacy 

sites (including Schooner), it was 267 mR.

The offsite TLD and PIC results remained consistent 

with previous years’ background radiation levels and 

are well within average background levels observed in 

other parts of the U.S. and with the 121 mR/yr level 

measured on the NTS. The highest total annual gamma 

exposure measured off site, based on the PIC detectors, 

was 183.96 mR/yr 

at Milford, Utah (at 

4,957 feet elevation). 

The lowest offsite 

rate, based on the PIC 

detectors, was 58.87 

mR/yr at Pahrump, 

Nevada (at 2,675 feet 

elevation).

NTS Background 

Gamma Radiation

121 mR/yr – This is the 

background radiation 

measured at 10 TLD 

stations in areas isolated 

from past and present 

nuclear activities.

2007 CEMP Air Surveillance Network

Direct exposure to gamma radiation is measured at 109 TLD stations on the NTS.

Exposure is reported in units called 

milliroentgens (mR). 

Generally, a 1 mR gamma exposure from the 

most common external radionuclides produces 

a 1 mrem dose.
15

Average Background Radiation of Selected U.S. Cities 

(Excluding Radon)

City

Elevation Above 

Sea Level 

(feet)

Radiation 

Exposure 

(mR/yr)(a)

Denver, Colorado 5,280 164.6

Wheeling, West Virginia 656 111.9

Rochester, New York 505 88.1

St. Louis, Missouri 465 87.9

Portland, Oregon 39 86.7

Los Angeles, California 292 73.6

Fort Worth, Texas 650 68.7

Richmond, Virginia 210 64.1

Tampa, Florida 3 63.7

New Orleans, Louisiana 0 63.7

(a) Source: < http://www.wrcc.dri.edu/cemp/Radiation.html>

 “Radiation in Perspective,” August 1990, as accessed on 7/28/2008

Average Direct Radiation Measured in 2007

 Location

Elevation 

Above Sea 

Level (feet)

Radiation 

Exposure 

(mR/yr)

NTS - Schooner TLD station 5,660 750

NTS - 35 Legacy Site TLD stations 3,077–5,938 267

Warm Springs Summit, Nevada CEMP PIC station 6,290 176

Twin Springs, Nevada PIC station 5,055 170

NTS - 17 Waste Operation TLD stations 3,176–4,021 147

NTS - 10 Background TLD stations 2,755–5,938 121

St. George, Utah PIC station 2,600 81

Pahrump, Nevada PIC station 2,550 72

NTS Mercury Fitness Track TLD station 3,769 61

Range in Radioactivity/Radiation Levels

Measured at Offsite and Onsite Air Sampling Stations

Average Gross Alpha

(x 10-15 μCi/mL)

Average Gross Beta

(x 10-14 μCi/mL)

Offsite 

(CEMP)

Onsite

 (NSTec)

Offsite

(CEMP)

Onsite

(NSTec)

Highest 

Average 

Value

2.75

(Las Vegas)

3.00

(Bunker 9-300)

2.66

(Mesquite)

2.32

(Sugar Bunker)

Lowest 

Average 

Value

0.98

(Nyala Ranch)

1.48

(Gate 20-2P)

1.95

(Nyala Ranch)

1.99

(Little Feller 2N)

Estimated Quantity of Pollutants Released 

into the Air from NTS Operations in 2007

Category Tons

Criteria Air Pollutants:

Particulate Matter (PM10)(a) 0.54

Carbon Monoxide (CO) 0.51

Nitrogen Oxides (NOx

) 1.21

Sulfur Dioxide (SO2

) 0.01

Volatile Organic Compounds (VOC) 1.14

Hazardous Air Pollutants (HAPs) 0.02

Lead 0.04

(a)Particulate matter equal to or less than 10 microns in diameter

Gross Alpha and Beta 

Radioactivity – Gross alpha and gross 

beta radioactivity was detected at all NTS 

and CEMP stations at levels consistent with 

previous years. Levels of gross alpha and 

gross beta at all stations reflect radioactivity 

primarily from naturally occurring radioactive 

materials.

Nonradioactive Air Emissions

The release of air pollutants is regulated 

on the NTS under a Class II air quality 

operating permit. Class II permits are 

issued for “minor” sources where annual 

emissions must not exceed 100 tons of any 

one criteria pollutant, or 10 tons of any one 

of the 189 hazardous air pollutants (HAPs), 

or 25 tons of any combination of HAPs. 

Common sources of such air pollutants on the 

NTS include particulates from construction, 

aggregate production, surface disturbances, 

fugitive dust from driving on unpaved roads, 

fuel-burning equipment, open burning, fuel 

storage facilities, and chemical release tests 

conducted at the NPTEC on Frenchman Flat 

playa in Area 5. 

An estimated 3.41 tons of criteria air pollutants were 

released on the NTS in 2007. The majority of the 

emissions were nitrogen oxides from diesel generators 

and VOCs from the bulk storage of gasoline. Total 

air emissions of lead, also a criteria pollutant, was 

0.04 tons. The quantity of HAPS released in 2007 was 

0.02 tons. No emission limits for any air pollutants 

were exceeded, and there were no discharges of 

nonradiological hazardous materials off the NTS or off 

its satellite facilities in 2007.
16

Offsite Radiological Monitoring of 

Groundwater 

NNSA/NSO’s comprehensive radiological 

environmental monitoring program includes sampling 

and analysis of groundwater and natural springs off of 

the NTS to determine if groundwater contamination 

from past nuclear testing poses a current threat to 

public health and the environment. In 2007, NSTec 

conducted radiological monitoring of 14 offsite wells 

and 4 offsite springs. The wells included 4 private or 

community drinking water wells, and 10 NNSA/NSO 

wells drilled for hydrogeologic investigations including 

groundwater flow modeling. All of the NSTec-sampled 

wells and springs are in Nevada within 19 miles from 

the western and southern borders of the NTS (see map 

on page 17). 

The DRI, through the CEMP, is tasked by 

NNSA/NSO to provide independent verification 

of the tritium concentrations in some of the offsite 

groundwater wells, municipal water supply systems, and 

springs used for water supplies in areas surrounding the 

NTS. Samples collected by DRI provide a comparison 

to the results obtained by NSTec. In 2007, the CEMP 

offsite water sampling locations included 21 wells, 3 

surface water supply systems, and 4 springs located in 

selected towns and communities within 240 miles from 

the NTS (see map below). 

NSTec offsite water samples are analyzed for tritium, 

man-made gamma-emitting radionuclides, and gross 

alpha and gross beta radioactivity. Tritium is the sole 

radionuclide for which CEMP water sample analyses are 

run.

All water samples from the offsite springs, wells, and 

surface water supplies monitored by NSTec and the 

CEMP had levels of tritium below the approximate 

minimum detectable concentration (MDC) of 26 pCi/L, 

except for the Henderson municipal water system 

sample of 32.2 pCi/L. The water in samples from 

Henderson originate from Lake Mead. Slightly elevated 

tritium activities in Lake Mead are well documented by 

Tritium

No offsite springs, surface water supplies, 

or wells had levels of tritium that were 

significantly above the minimum detectable 

concentration of 26 picocuries per liter 

(pCi/L). 

2007 CEMP Water Monitoring Locations
17

2007 NSTec Water Monitoring Locations
18

previous investigations and are due to residual tritium 

persisting in the environment that originated from 

global atmospheric nuclear testing.

No offsite springs 

or wells contained 

any man-made 

gamma-emitting 

radionuclides. 

Most offsite wells 

and all offsite spring samples contained detectable 

gross alpha and gross beta activity that is most likely 

from natural sources. All levels were less than the 

U.S. Environmental 

Protection Agency (EPA) 

limits set for drinking water 

(15 pCi/L for gross alpha 

and 50 pCi/L for gross 

beta), except Barn Spring. 

This spring’s measured 

gross alpha activity was 

19 ± 2.4 pCi/L. 

20,000 pCi/L – This is the 

EPA-established maximum 

concentration limit for tritium 

in drinking water. 

Range in Groundwater Tritium Levels 

Measured Off the NTS in 2007

pCi/L

CEMP NSTec

Offsite Supply Wells -9.7 to 19.3 -17 to 2.1

Offsite Springs/

Surface Waters

-6.4 to 32.2* -9.5 to 6.8

Offsite NNSA/NSO 

Monitoring Wells

-- -17 to 17

*Only one sample (from Henderson municipal water 

system) was above the MDC. The MDC is the 

smallest amount of tritium in a sample that can be 

distinguished from background radiation in the sample 

with 95% confidence. Gamma-Emitting

Radionuclides

No offsite springs 

or wells contained 

any man-made 

gamma-emitting 

radionuclides. 

Offsite monitoring indicates that 

there has been no offsite migration 

of man-made radionuclides from NTS 

underground contamination areas.

Radioactivity in onsite groundwater and surface waters 

of the NTS is monitored annually in order to (1) ensure 

that NTS drinking water is safe, (2) determine if 

permitted facilities on the NTS are in compliance with 

permit discharge limits for radionuclides, (3) estimate 

radiological dose to onsite wildlife using natural 

and man-made water sources, and (4) determine 

if groundwater is being protected from disposed 

radioactive wastes at the Area 3 and Area 5 RWMSs. In 

2007, the onsite water monitoring network consisted 

of 5 potable and 4 non-potable water supply wells, 

16 monitoring wells, 1 tritiated water containment pond 

system, and 2 sewage lagoons (see map on page 17).

Water Supply Wells – The 2007 data continue 

to indicate that underground nuclear testing has not 

impacted the NTS drinking water supply network. 

None of the onsite water supply wells had detectable 

concentrations (i.e., above MDC) of tritium or 

detectable concentrations of man-made gammaemitting radionuclides. The gross alpha and gross 

beta radioactivity detected in potable water supply 

wells represent the presence of naturally occurring 

radionuclides and did not exceed EPA limits drinking 

water limits.

Range in Groundwater Tritium Levels 

Measured On the NTS in 2007

pCi/L

Onsite Supply Wells -17 to 14

Onsite Monitoring Wells -16 to 390*

*Four onsite monitoring wells had tritium levels above 

MDCs and all four are within 1 kilometer (0.6 miles) of 

underground nuclear tests.

Monitoring Wells – Some migration of 

radionuclides from the underground test areas to NTS 

monitoring wells has probably occurred, although the 

migration distances appear to be very short. Four 

onsite monitoring wells (PM-1, UE-7NS, U-19BH, 

and WW A) had detectable concentrations of tritium 

in 2007 ranging from 23 to 390 pCi/L, all well below 

the drinking water limit of 20,000 pCi/L. Each of 

these monitoring wells is located within 0.6 miles of an 

historical underground nuclear test; all have consistently 

had detectable levels of tritium in past years, and no 

trend of rising tritium concentrations in these wells has 

been observed since 2000. 

No man-made radionuclides were detected by gamma 

spectroscopy analyses at concentrations above detection 

limits in any of the monitoring wells in 2007. All of 

the 16 monitoring wells had measurable gross alpha 

and gross beta levels, which are likely from natural 

sources. Only one of the monitoring wells (ER-19-1) 

had gross alpha and gross beta activity above the EPA 

No drinking water wells on the NTS 

contained detectable tritium or 

man-made gamma-emitting radionuclides.

Onsite Radiological Monitoring of Groundwater
19

Sampling Oasis Valley, May 2008 (photo by Terry Sonnenburg)

completed in the vicinity 

of some underground 

tests and at other 

locations on the NTS. 

If the tritium level 

exceeds 200,000 pCi/L 

during these drilling 

operations, contaminated water is pumped from the 

wells and diverted to lined sumps (containment ponds) 

for evaporation, as required by the state. During 2007, 

water containing tritium was pumped from two wells in 

Area 5 (RNM #1, RNM #2S) and one in Area 3 (U-3cn 

PS #2). Only the waters discharged from U-3cn PS #2 

needed to be diverted to a lined sump. Tritium levels 

were 7.7 million pCi/L in groundwater samples from 

this well. 

Permitted Sewage Lagoons – Two permitted 

sewage lagoons (Area 6 Yucca and Area 23 Mercury) are 

sampled annually and analyzed for tritium, gross alpha 

and beta activity, and gamma-emitting radionuclides. As 

during previous years, none of these were detected in 

the lagoon water samples. 

Onsite Nonradiological Monitoring 

of Drinking Water and Wastewater

NNSA/NSO operates a network of six permitted wells 

that comprise three permitted public water systems on 

the NTS which supply the drinking water needs of NTS 

workers and visitors. NNSA/NSO also hauls potable 

water to work locations at the NTS that are not part 

of a public water system. Monitoring results for 2007 

indicated that water samples from the three public water 

systems and from the potable water hauling trucks 

met the National 

Primary and 

Secondary Drinking 

Water Standards. 

Industrial discharges 

on the NTS are 

limited to two 

operating sewage 

lagoon systems, one at Yucca Lake in Area 6 and one 

at Mercury in Area 23. Under the conditions of state 

of Nevada operating permits, liquid discharges to these 

sewage lagoons are tested quarterly for biochemical 

oxygen demand, pH, and total suspended solids. 

Sewage lagoon pond waters are sampled annually 

for a suite of toxic chemicals. Quarterly and 

annual analyses of sewage influent and of 

pond waters, respectively, showed that all water 

measurements were within permit limits (often 

below detection levels) with one exception. One 

measure of 5-day Biological Oxygen Demand 

(BOD5

) Mean Daily Load was exceeded at the 

Area 23 Mercury lagoons in the fourth quarter.

Containment Ponds – Five constructed basins 

collect and hold water discharged from E Tunnel in 

Area 12 where nuclear testing was conducted in the 

past. The water is perched groundwater that has 

percolated through fractures in the tunnel system. 

Monitoring of the effluent waters from E Tunnel 

is conducted to determine if radionuclides or other 

contaminants exceed the allowable contaminant 

levels regulated under a state water pollution control 

permit. Tritium concentrations in tunnel effluent 

waters in 2007 were lower than the permit limit. The 

E Tunnel containment ponds are fenced and posted 

with radiological warning signs. Given that the ponds 

are available to wildlife, game animals are sampled 

by NSTec to assess the potential radiological dose to 

humans via ingestion of game animals exposed to 

these ponds and to evaluate the radiological impacts to 

wildlife.

Tritiated water is also pumped into lined sumps during 

studies conducted by the Underground Test Area 

(UGTA) Subproject. Its mission is to characterize the 

groundwater beneath the NTS and adjacent lands for 

the purpose of developing analytical models to predict 

groundwater movement and contaminant transport. To 

do this, suitable wells are drilled and existing wells re2007 Monitoring Results for E Tunnel Effluent Waters 

Pertaining to Water Pollution Control Permit NEV 96021

Parameter

State Water Pollution 

Control Permit Limit 

(pCi/L)

Average Measured 

Concentration

(pCi/L)

Tritium 1,000,000 590,000

Gross Alpha 35 12.1

Gross Beta 100 49.3

UGTA Lined Sumps

In 2007, one lined sump in 

Area 3 held groundwater 

having 7.7 million pCi/L of 

tritium. 

NTS Drinking Water

The public water system which 

supplies drinking water to NTS 

workers and visitors meets all 

National Primary and Secondary 

Drinking Water Standards. 

limits for drinking water. The activity levels in ER-19-1 

is consistent with the levels reported from past years’ 

sampling and may likely be attributed to elevated levels 

of dissolved solids. 
20

Significant Environmental 

Accomplishments 

Environmental Restoration 

The cleanup of sites contaminated by past DOE 

operations and the hydrogeological investigations 

supporting characterization of underground 

nuclear contamination areas are the most significant 

environmental work performed by NNSA/NSO 

each year. The DOE, U.S. Department of Defense, 

and the State of Nevada Division of Environmental 

Protection identify a work scope and milestone 

schedule for the cleanup and safe closure of the 

contaminated aboveground sites and for the field 

investigations and model development necessary to 

characterize the underground sites. In 2007, 114 

contaminated aboveground sites were closed safely. 

These aboveground sites consist of facilities and land, 

and are referred to as Industrial Sites. In addition to 

the Industrial Sites closures, extensive progress was 

made toward the development of hydrologic models 

describing groundwater flow and possible radionuclide 

transport from the primary underground sites into 

the groundwater underlying public lands outside the 

boundaries of the NTS. This involved completing 

the compilation, analysis, and documentation of all 

transport parameters which will be used to build the 

flow model for CAU 98 (Yucca Flat/Climax Mine) and 

completing the 3D hydrostratigraphic framework model 

for CAU 99 (Rainier/Shoshone). 

Pollution Prevention and Waste 

Minimization 

Pollution prevention and waste minimization activities 

on the NTS result in reductions to the volume and/

or toxicity of waste generated on site. In 2007, the 

Material Exchange Program diverted 1.2 tons of 

chemicals, office supplies, and equipment from solid 

and hazardous waste landfills in 2007 and a total of 

210 tons of usable materials from such landfills since 

the program’s inception in 1998. Other significant 

waste reduction efforts continued in 2007, such as 

sending bulk used oil to an offsite vendor for recycling 

(76.6 tons), and offsite recycling of mixed paper and 

cardboard (606.2 tons). Overall, a reduction of 167 

tons of hazardous wastes and 1,698.5 tons of solid 

wastes was realized in 2007.

NNSA/NSO received an Environmental Stewardship 

Award in 2007 for the renovation project of 

Building B-3 at the NLVF. Building B-3 had been 

vacant for two years, and rather than demolish it, 

NNSA/NSO decided to remediate, renovate, and 

upgrade it. This project resulted in extending the life 

cycle of the building, reconfiguring office space to 

increase capacity, conserving resources, reducing waste 

material going to landfills, contributing to recycling 

efforts, and eliminating a 20-mile round-trip drive for 

displaced employees. It also may result in Building B-3 

receiving a certification under the Leadership in Energy 

and Environmental Design (LEED) Green Building 

Rating System administered by the U.S. Green Building 

Council.

In 2007, NSTec also removed 1,180 tons of unneeded 

raw materials that had been stored in the open at 

the NLVF. Needed materials were moved inside or 

covered. This cleanup project eliminated any potential 

to pollute storm water and resulted in the recycling of 

413 tons of material. This action also exempted the 

facility from conducting difficult and costly monitoring 

of storm water runoff and other compliance actions 

required under the Clean Water Act. 

Ecological Monitoring

NTS biologists performed numerous surveys and 

mitigation actions under permit with the U.S. Fish and 

Wildlife Service to ensure that no desert tortoise was 

accidentally harmed or killed during NTS activities in 

2007. The desert tortoise is protected as a threatened 

species under the Endangered Species Act and it 

occurs in suitable habitat on the southern third of the 

NTS. Numerous species, considered by federal and 

state agencies to be sensitive or important to track, 

are known to occur on the NTS and include 20 plants, 

1 mollusk, 2 reptiles, over 250 birds, and 26 mammals. 

8- to 10-day-old western burrowing owl chicks in culvert 

burrow on Pahute Mesa (Photo by D. B. Hall, June 20, 2007)
21

Biologists continued to monitor some of these species 

in 2007, which included western red-tailed skinks, 

western burrowing owls, bats, and mountain lions. As 

a result, the documented distribution patterns of these 

species on the NTS have been increased, and other 

species new to the NTS have been recorded. Data on 

species’ movements, genetic relationships, and activity 

patterns have been gathered using the latest research 

techniques including DNA analysis, radio-isotopic 

analysis, and motion-activated cameras.

Biologists continued working in cooperation with 

Southern Nevada Health District (SNHD) personnel to 

determine if mosquitoes on the NTS carry West Nile 

Virus. As in previous years, no infected mosquitoes 

were found. 

Cultural Resources 

The ongoing historical evaluation of the nuclear testing 

tunnels in Rainier and Aqueduct mesas on the NTS is the 

first time anywhere that horizontal nuclear test beds have 

been studied for their historical significance. The tunnels 

are treated as historic landscapes and the importance of 

their contributions to the Cold War effort have qualified 

them to be exempted from the rule that buildings and 

structures must be at least 50 years old to be considered 

for the National Register of Historic Places. With this 

exemption, the B and E tunnels have been determined 

eligible to the National Register of Historic Places. This 

significant determination will allow the tunnels’ historic 

landscapes to be preserved in place.
For more information, contact:

U.S. Department of Energy

National Nuclear Security Administration

Nevada Site Office

Office of Public Affairs

P.O. Box 98518

Las Vegas, NV 89193-8518

phone: 702-295-3521

fax: 702-295-0154

email: nevada@nv.doe.gov

http://www.nv.doe.gov