Commentary History Informational

Uranium Contamination of the Puerco River: 1979-Present

By: Nina Chester

Uranium and uranium mining have been a constant force in my life. Three years before I was born, on July 16, 1979, a uranium mill tailings pond[1] ruptured at the United Nuclear Corporation (UNC) uranium mining operation in Church Rock, New Mexico – 40 miles upstream from my hometown of Lupton, Arizona on the Navajo Nation.[2] The tailings pond released “94 million gallons of [highly acidic] mill waste fluids and 1100 tons of tailings solids,” including “uranium-238, thorium-230, radium-226, lead-210 and polonium-210” into Pipeline Arroyo, a tributary of Puerco River.[3] Additional released contaminants included “elemental lead, molybdenum, arsenic and selenium,” “acidity,” and “high levels of dissolved salts, particularly sulfate.”[4] Adding insult to injury, the rate at which the waste traveled was helped along by a “flow of 5000 gallons per minute of water continuously pumped into Pipeline Arroyo by routine dewatering operations at [further] upstream uranium mines.”[5] The flow eventually ceased near Chambers, Arizona, “100 river miles downstream from the UNC mill.”[6]

The incident is now known as the Church Rock Uranium Mill Spill of 1979. It is “the largest single release of liquid radioactive waste recorded in the United States and the fifth largest release of solid radioactive waste.”[7] It is also likely one of the quietest large-scale radioactive spills to occur in the United States. Lupton community members cannot recall being fully informed of the dangers posed by the radioactive material, and scientific research regarding the impact to health and the environment was not reported to them.

On October 22, 1979, the House Subcommittee on Energy and the Environment of the Committee on Interior and Insular Affairs held an Oversight Hearing on the “Mill Tailings Dam Break at Church Rock, New Mexico” in Washington, D.C.[8] Both the Subcommittee and the Committee were chaired by Representative Morris K. Udall from Arizona.[9] In the Chairman’s opening statement he declared, “our concern for these matters derives from three areas of the Interior Committee’s jurisdiction, dam safety, on which we have legislated; Indian affairs and finally regulation of the nuclear industry.”[10] The subcommittee consulted “Dr. Bruce Tschantz, a dam safety expert and professor of civil engineering at the University of Tennessee” to review “pertinent engineering assessments and licensing materials.”[11] Dr. Tschantz found issue with the proposed dam materials, the dam design, and surmised that the quality assurance procedures detailed in the design plan were not followed.[12] The Army Corps of Engineers also submitted a report for the hearing, which comported with Dr. Tschantz’s assessments and highlighted three key findings.[13] The report found that the planned buttress of tailings against the dam for reinforcement was never completed, the dam was showing signs of cracking in 1977 and 1978 but State regulatory authorities were not notified by the company, and “the design of the dam did not incorporate all the necessary protective measures recommended by the company’s engineering consultant.”[14]

Shortly after the spill, the “subcommittee held an oversight hearing on the Nuclear Regulatory Commission’s agreement States program, under which the State of New Mexico is permitted to license tailings impoundments.”[15] It found “significant problems” with both the management of the program by the federal commission and the state’s technical and regulatory capacity.[16] Therefore, as stated by the Chairman, “at least three and possibly more Federal and State regulatory agencies had ample opportunity to conclude that such an accident was likely to occur.”[17]

At the time of the hearing, the total cleanup completed by UNC was less than one percent and UNC was facing a number of problems.[18] Mr. Paul Robinson, environmental analyst for the Southwest Research and Information Center remarked that, in addition to UNC’s inability to build and operate to the standards they were licensed at, they miscalculated the amount of tailings they could back-fill and were left with excess tailings, which hold 85 percent of the original radioactivity.[19] Mr. Frank E. Paul, Navajo Vice-Chairman, remarked that “a smaller incident at Three Mile Island commanded a Presidential Commission. Yet today’s hearing represents the first serious national concern for this incident, and it is now over 3 months since the dam failed.”[20]

A post-spill summary report by the State of New Mexico Health and Environment Department’s Environmental Improvement Division found that “the dewatering effluents and natural runoff that now dominate surface water flows contain environmentally significant levels of radioactive lead, radium and uranium, as well as elemental lead, selenium and molybdenum. [ . . . ] Most of these substances come from uranium mine dewatering effluents.”[21] In other words, UNC and other mine operators in the Church Rock area were using the Puerco River as a radioactive dump for years.

An additional aspect described in New Mexico’s report was the land ownership pattern along the Puerco River. “Checkerboard” is a swath of land containing a mixture of property types all within close proximity of one another.[22] The land UNC leased for its mill and tailings pond was categorized as “fee simple” land, owned by non-Indian lessors, and it was not considered reservation land.[23]  

Kee Joe Benally, a well-regarded community member from Lupton, attempted to sue UNC Resources, Inc. in Navajo Tribal Court. Benally had the support of the Navajo Tribal Council via legislation passed on February 13, 1980, expanding the civil jurisdiction of the Navajo Nation Courts to include civil actions “in which the defendant is a resident of Navajo Indian country, or has caused an action to occur in Navajo Indian country.”[24] Unsurprisingly, the District Court of New Mexico held that:

Navajo Tribal Court jurisdiction over non-Indian civil defendants necessarily involves the tribe’s external relations, and it is not a power needed to protect tribal self-government because the tribal government has always been able to function without it. Such jurisdiction is therefore not part of the tribe’s retained sovereignty.[25]

Accordingly, the Navajo Tribe had no jurisdictional authority to take matters into its own sovereign hands.[26] Upon issue of judgment, UNC opportunistically requested a declaration of non-liability as a tortfeasor, which the court refused.[27]

The New Mexico post-spill summary report noted three potential human contact mechanisms: “[w]ater-borne contaminants in the Puerco River may infiltrate into the ground and impair the quality of shallow ground water[,] because groundwater moves slowly, such degradation could remain undetected until a private well is affected.”[28] Second, “[l]ivestock could ingest contaminated sediments by drinking water from the Puerco River,” resulting in long-term exposure, which then could be consumed by people.[29] Third, “[c]ontaminated sediments [ . . . ] may be suspended as dust and inhaled by local residents or deposited on vegetation and consumed by livestock.”[30]

In 2000, the Navajo Nation requested that the United States Environmental Protection Agency take the lead on the Northeast Church Rock mine cleanup, as it is identified today.[31] USEPA and United Nuclear Corporation (acquired by General Electric) continue to work together to complete federal administrative processes and enforcement protocols.[32] According to USEPA, as of January 2020,

200,000 tons of contaminated soil has been removed from the residential area and brought back to the mine waste pile. The mine waste pile has been temporarily covered and stabilized until it can be removed. [ . . . ] In September 2018, UNC/GE (General Electric) submitted a request for a license amendment (which includes the completed design) to the Nuclear Regulatory Commission (NRC) to build a repository for the NECR mine waste at the UNC Mill Site. NRC is currently reviewing the request.[33]

The USEPA has identified a boundary for the Northeast Church Rock mine that does not include the Puerco River, despite the dewatering practices that were exercised during the mine’s operation from 1967-1982.[34] Common arguments against a cleanup of Puerco River include: naturally occurring uranium as the source of environmental contamination, high cleanup costs, and low population in the affected areas. However, the Comprehensive Environmental Response, Compensation, and Liability Act defines facility as “any site or area where a hazardous substance has been deposited, stored, disposed of or placed, or otherwise come to be located . . . .”[35] According to the federal statute, the Rio Puerco is part of the Northeast Church Rock mine facility.

As New Mexico Senator Tom Udall stated in his opening remarks as Chair of the Senate Subcommittee on Children’s Health and Environmental Responsibility, “regardless of our personal beliefs about nuclear weapons, nuclear power or future uranium mining, everyone should agree the Nation and the companies that profited from uranium development owe a debt to communities with legacy contamination and that can only be paid in full with a complete cleanup.”[36]

If you are interested in learning more about the progress of the Northeast Church Rock mine cleanup, the US EPA has a comprehensive website where it continues to report on the progress of cleanup at this and the hundreds of other abandoned uranium mine sites and features left on the Navajo Nation today. You may also contact Ms. Priscilla Tom, the community coordinator for Northeast Church Rock mine, with any questions pertaining to the site cleanup. There are non-government organizations that are also doing important work to develop a strong case, such as: the Navajo Birth Cohort Study, conducted by Dr. Johnny Lewis; the Red Water Pond Road Community Association; Former Navajo Nation Council Delegate Jonathan Perry with Eastern Navajo Diné Against Uranium Mining, in partnership with the New Mexico Environmental Law Center; Dr. Tommy Rock (Diné); Ms. Leona Morgan; and many others.

Lastly, and most importantly, let us acknowledge the countless beings, human and otherwise, who have been affected by uranium mining and exposure to hazardous materials. The injustice at the hands of unscrupulous businesspeople and the United States federal government; perpetuated by the former, is not right. Even though the work is emotionally laborious and change is slow, we will keep striving to move forward.


[1] “Mine tailings dam. An industrial waste dam in which the waste materials come from mining operations or mineral processing. It is usually built in stages over the life of the mine. The waste products are often conveyed as fine material suspended in water to the reservoir impounded by the embankment.” U.S Department of Labor Mine Safety and Health Administration, MSHA Handbook Series Handbook Number PH21-V-6, A9-6 (January 2021).

[2] Jere Millard, Bruce Gallaher, Davis Baggett & Steven Cary, New Mexico Environmental Improvement Division Health and Environment Department, Summary Report of the Church Rock Uranium Mill Tailings Spill: A Health and Environmental Assessment 1 (1983).

[3] Id.

[4] Id.

[5] Id.

[6] Id.

[7] Id.

[8] Mill Tailings Dam Break at Church Rock, New Mexico: Oversight Hearing Before the Subcomm. on Energy and the Env’t of the Comm. on Interior and Insular Affairs,96th Cong. 1 (1979).

[9] Id. at 1.

[10] Id.

[11] Id. at 2-3.

[12] Id. at 3.

[13] Id.

[14] Id.

[15] Id.

[16] Id.

[17] Id. at 2.

[18] Id. at 47.

[19] Id. at 49.

[20] Id. at 6.

[21] Id. at 21.

[22] Millard et al., supra note 2, at 8.

[23] UNC Res., Inc. v. Benally, 514 F. Supp. 358, 362 (D.N.M. 1981).

[24] Id. at 360.

[25] Id. at 362.

[26] Id. at 363.

[27] Id. at 364.

[28] Millard et al., supra note 2, at 1.

[29] Id.

[30] Id.

[31] U.S. EPA, Northeast Church Rock Mine Site Update (2020),

[32] Id.

[33] Id.

[34] Id.

[35] Comprehensive Environmental Response, Compensation, and Liability Act, 42 U.S.C. § 9601 (2018).

[36] Oversight Hearing on Federal Actions to Clean Up Contamination From Legacy Uranium Mining And Milling Operations Before the Subcomm. on Child. Health and the Env’t Responsibility of the Comm. on Env’t and Pub. Works, 112th Cong. (2011).

By Tribal Law Journal Blog

The Tribal Law Journal was established in fall 1998 for the purpose of promoting indigenous self-determination by facilitating discussion of the internal law of the world’s indigenous nations. The internal law of indigenous nations encompasses traditional law, western law adopted by indigenous nations, and a blend of western and indigenous law. Underscoring this purpose is the recognition that traditional law is a source of law.

One reply on “Uranium Contamination of the Puerco River: 1979-Present”

I still cannot get over this statement, “quietest large-scale radioactive spills to occur in the United States.” Powerful article, Nina!


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