The NRC, as an independent regulatory 

agency, ensures the safe use of radioactive 

material while protecting people and the 

environment. The NRC regulates uranium 

milling and mill tailings disposal on tribal 

reservations through licensing, inspection 

and enforcement of regulations.

The NRC does not regulate mining.

Uranium Milling

Milling is the first step in making natural 

uranium ore into fuel for nuclear reactors. 

Uranium mills use chemicals to extract 

uranium and make “yellowcake,” a powder 

that can be processed into fuel. They produce 

“mill tailings,” a sandy waste containing 

heavy metals and radioactive materials. 

In 1978 Congress passed a law to ensure 

that uranium mill tailings would be safely 

managed into the future. Under that law, the 

Department of Energy (DOE) is responsible 

for the long-term care and maintenance 

of the four former mill sites on the Navajo 

Nation: Mexican Hat, Utah; Monument 

Valley, Ariz.; Shiprock, N.M.; and Tuba City, 

Ariz. The NRC oversees DOE’s management 

of these sites.

Contact the NRC

Tribal Liaison Program

The NRC Tribal Liaison team will foster 

effective consultation, cooperation, and 

communication between the NRC and 

Tribal governments. 

Materials Decommissioning

 (301) 415-6749

Tribal Outreach

(301) 415-8059

Email:

 Tribal_Outreach.Resource@nrc.gov

Mail:

U.S. Nuclear Regulatory Commission

Tribal Liaison Program

Mailstop: T8D36

Washington, DC 20555-0001

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U.S. Nuclear Regulatory Commission’s 

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Uranium Contamination

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NRC’s Role in the Five-Year Plan

NRC Tribal Liaison Program

The NRC Tribal Liaison Program conducts outreach 

and seeks to engage Tribal Nations in the NRC’s safety 

and security mission. For the Five-Year Plan, the NRC 

Tribal Liaison Program is active in the Community 

The NRC and other Federal agencies are working to address uranium 

contamination in consultation with the Navajo Nation. In 2007, the agencies 

developed a coordinated Five-Year Plan that outlined a strategy to gain a 

better understanding of the scope of the problem and address the greatest 

risks first. In addition to the NRC, the Federal agencies are the Department of 

Energy (DOE), the Environmental Protection Agency (EPA), the Bureau of 

Indian Affairs, the Agency for Toxic Substances and Disease Registry, and the 

Indian Health Service. 

During the first five years, the agencies focused on collecting data, identifying 

the most imminent risks and addressing contaminated structures, water 

supplies, mills, dumps, and mines with the highest levels of radiation. 

They learned more about the scope of the problem and the work that needs 

to be done. 

In 2014, the agencies published a second Five-Year Plan that builds on the 

information gathered and the lessons learned during the first five years. The 

agencies are committed to continuing to work with the Navajo Nation to 

reduce the risks to health and the environment. Under the Five-Year Plan 

each agency plays a specific role. 

Mill Tailings Sites

The NRC’s role is to provide continuing oversight of the uranium mill tailings 

disposal sites on the Navajo Nation that have been transferred to DOE. As the 

licensee, DOE has responsibility for long-term surveillance and maintenance 

of the disposal sites. The NRC reviews and provides comments on any 

reports DOE produces about the sites. The NRC conducts inspections at the 

sites in conjunction with DOE. If DOE revises the long-term surveillance 

plan or groundwater compliance action plan for a disposal site, the NRC 

will work with the DOE and all other authorities to ensure that the plans 

are adequate. The NRC will also review, and if the plan is adequate, concur 

on groundwater compliance action plans for the former processing site in 

Monument Valley.

UNC Mill Site

United Nuclear Corp. (UNC) is licensed by the NRC to possess uranium mill 

tailings at the UNC mill site. They will be filing a license amendment to allow 

Northeast Church Rock mine waste to be disposed in the NRC-licensed 

facility at the mill. The NRC will work closely with EPA, DOE, the New 

Mexico Environment Department, and the Navajo Nation during the NRC’s 

review of the amendment request. The NRC will review the amendment 

request and the design of the disposal unit to ensure that they meet safety and 

environmental requirements.

Outreach Network, and works to enhance knowledge and 

community empowerment in achieving the goals of the 

Plan. The NRC provides information and education on 

uranium milling and radiation on the Navajo Nation.

Tuba City Disposal Site - A former 

ore processing site that operated from 

1956 to 1966. The disposal cell 

contains about 2.5 million tons of 

residual radioactive material.

Monument Valley Processing Site – A 

former ore processing site that operated 

from 1955 to 1968. The residual 

radioactive material was relocated 

to the Mexican Hat disposal 

site from 1992 to 1994.

Fact Sheet

UMTRCA Title I

Monument Valley, Arizona, Processing Site

This fact sheet provides information about the Uranium Mill Tailings Radiation Control Act of 1978

Title I processing site at Monument Valley, Arizona. This site is managed by

the U.S. Department of Energy Office of Legacy Management.

Site Description and History

The Monument Valley processing site is located on the 

Navajo Nation in northeastern Arizona, approximately 

15 miles south of Mexican Hat, Utah, on the west side of 

Cane Valley. A uranium-ore processing mill operated at the 

site from 1955 to 1968 on property leased from the Navajo 

Mexican Hat Disposal Site – A former 

ore processing site that operated from 

1957 to 1965. The disposal cell 

contains about 4.4 million tons of 

residual radioactive material.

Fact Sheet

UMTRCA Title I

Mexican Hat, Utah, Disposal Site

This fact sheet provides information about the Uranium Mill Tailings Radiation Control Act of 1978 

Title I processing site at Mexican Hat, Utah. This site is managed by 

the U.S. Department of Energy Office of Legacy Management.

Location of the Mexican Hat, Utah, Disposal Cell

Site Location and History

The Mexican Hat disposal site is located on the Navajo 

Reservation in southeast Utah, 1.5 miles southwest of the 

town of Mexican Hat and 1 mile south of the San Juan 

River. The site is 10 miles north of the Utah-Arizona border 

and approximately 15 miles north of the Monument Valley 

processing site. The site is also the location of a former 

uranium-ore processing mill. Texas-Zinc Minerals Corporation 

constructed the Mexican Hat mill on land leased from the 

Navajo Nation and operated the facility from 1957 to 1963. 

Atlas Corporation purchased the mill in 1963 and operated 

it until it closed in 1965. A sulfuric acid manufacturing plant 

operated at the site from 1957 to 1970. Control of the site 

reverted to the Navajo Nation after the lease expired in 1970.

Much of the ore brought to the mill contained a considerable 

amount of copper sulfide and other sulfide minerals and was 

processed to recover both copper and uranium. The milling 

process produced radioactive tailings, a predominantly sandy 

material. Spent tailings were mixed with process water and 

pumped through a pipeline to two onsite tailings piles. 

The U.S. Department of Energy (DOE) completed surface 

remedial action at the site in 1995. Radioactive materials 

from the former upper tailings pile, demolished mill structures, 

and 11 vicinity properties were placed in a disposal cell 

constructed at the site of the former lower tailings pile. An 

additional 983,000 cubic yards (1.3 million dry tons) of tailings 

and associated waste were hauled from the Monument Valley, 

Arizona, Processing Site approximately 15 miles to the south 

and placed in the cell on top of contaminated materials from 

thMiHt itA ttl f itl36 illibi

Regulatory Setting

Congress passed the Uranium Mill Tailings Radiation Control 

Act (UMTRCA) in 1978 (Public Law 95-604), and DOE 

remediated 22 inactive uranium-ore processing sites 

under the Uranium Mill Tailings Remedial Action Project 

UNC Mill Site – An ore processing site 

that operated from 1977 to 1982 and is 

currently under reclamation.

UNC Mill Site photo courtesy: Environmental Protection AgencyAll other photos courtesy: Department of Energy

Shiprock Disposal Site – A former 

ore processing site that operated from 

1954 to 1968. The disposal cell contains 2.5 million tons of residual 

radioactive material.