A town on the edge of the Navajo Nation that unknowingly drank uranium-tainted water for at least 12 years.

Navajo babies showing increasing uranium concentrations during their first year of life.

Children swimming in natural pools near Cameron they later learned had been filled with water from abandoned uranium mines.

The stories about the impacts of Cold War-era uranium mining on the Navajo Nation became highly personal during a forum hosted at the Museum of Northern Arizona Wednesday night.

Four decades later, the subject has come to the fore again as a grandfathered uranium mine moves forward with operations south of Tusayan and a new president stokes fears about the reopening of 1 million acres of the Grand Canyon watershed outside the national park to new mining.

“The 20-year mineral withdrawal is now up for grabs under the current administration,” the Grand Canyon Trust’s Roger Clark said Wednesday night.

Among most at the forum, the thinking was obvious: Allowing more mining around the Grand Canyon is opening the door to repeating past mistakes.

But as it stands, researchers haven’t yet determined if data from soils, waters and living inhabitants largely supports or refutes such a fear. They are still nailing down possible sources of high uranium measured in a handful of waters in the watershed, are just starting to understand how water travels through rock layers that surround the breccia pipe uranium mines and have completed only an initial set of studies on how surface operations could impact nearby plants and animals.

What is clear, however, is that modern mining in the Grand Canyon isn’t simply a repeat of the past. Different mining methods, more rigorous regulations and a better understanding of underground water and geology make evaluation of the current risks its own, complicated beast.


On the Navajo Nation, uranium mines were blasted into plains, mesas and mountains across the landscape. The methods created radioactive waste piles, open tunnels and pits. Much of the mining, which occurred between World War II and the 1980s, predated the founding of the Environmental Protection Agency and the passage of associated environmental laws. Groundwater contamination from mining has stretched for miles and crossed state lines, and more than 500 abandoned uranium mines remain on the Navajo Nation. Just nine have seen cleanup or stabilization work by the EPA.

In the Grand Canyon area, two mines on the North Rim — Pinenut and Kanab North — are in various stages of closure while another, Arizona 1 is on maintenance status. At the grandfathered Canyon Mine south of Tusayan on the South Rim, mine owner Energy Fuels Resources has drilled a main shaft to about 1,500 feet and is continuing with ore evaluation and mine planning. Spokesman Curtis Moore said the company is not publicly announcing when it expects ore mining to begin, though past estimates were for mid-2018.

The mines have a much different uranium target than those on the Navajo Nation: large, underground vertical pipes of high-grade uranium ore that measure 200 to 300 feet in diameter and 1,500 to 2,500 feet in length. Mine shafts are dug parallel to the uranium-rich breccia pipes and from there miners tunnel horizontally into the ore. The ore is dug out, then scooped up with machines like small bobcats and transported to the surface, where it’s dumped in piles, said Frank Bain, a mining consultant who has worked in the industry for 40 years.

State and federal agencies regulate mining activities like the amount of ore that can be stockpiled at the surface and how dust must be contained onsite. Energy Fuels must submit quarterly and annual water quality data to the Arizona Department of Environmental Quality, spokeswoman Caroline Oppleman said in an email.

As for deeper groundwater, Moore said a wall of impermeable rock protects the aquifer beneath the mine shaft.

“Again, Energy Fuels and our regulators are confident that the Canyon Mine will have no impact on water,” Moore wrote in an email.


That sort of certainty isn’t echoed by the U.S. Geological Survey researchers tasked by the Interior Department with determining potential impacts of uranium mining to the Grand Canyon environment.

Five years into their research, USGS scientists haven’t yet answered whether mining will or won’t affect groundwater, much less as what level of contamination and for how long, said Fred Tillman, who is leading the team investigating water resource impacts.

The groundwater system is complex and not yet well-understood, though researchers are finding evidence of connections between the surface and the deepest aquifers that challenge the assertion of an impermeable barrier between them. (See related article)

The USGS is hoping more information will come from future spring and creek monitoring as well as a monitoring well installed in the perched aquifer near Canyon Mine.


It’s the job of Jo Ellen Hinck to figure out how uranium mining might affect animals and plants near the canyon. Her colleague Katie Walton-Day is measuring surface radiation and levels of uranium and other mining-related elements in soils around mine sites.

Five years after starting their research, Hinck said her team is just now getting a picture of what the data means. Walton-Day agreed that many information gaps still exist.

Among their initial findings:

  • Tadpoles living in Canyon Mine’s containment pond registered levels of selenium and arsenic above wildlife toxicity thresholds and significantly greater than tadpoles living in nearby ponds and springs. 
  • Studies measured significantly greater uranium concentrations in the plants and mammals at the now-closed Kanab North mine before reclamation began compared to Canyon Mine, which has not produced any ore to date.
  • Soil samples taken inside and outside of the perimeter of Canyon Mine indicate that mining-related constituents haven't made their way offsite during mine site development.


Even with the boost in research resources deployed across the Grand Canyon after the 2012 withdrawal decision, researchers themselves say it’s far from enough.

The USGS originally planned to have eight to 10 monitoring wells, for example, but so far it has received funding to drill only one into the shallow aquifer near Canyon Mine, Tillman said.

Dave Kreamer, a hydrologist with the University of Nevada Las Vegas who has spend decades researching water sources in the Grand Canyon, called current monitoring "totally inadequate" to detect possible contamination.

“I’ve seen countries in the developing world that have better monitoring of mine sites than what they’re exhibiting in Grand Canyon," Kreamer said. 

 The mines around the Grand Canyon also don’t have a spotless record.

  • In 2009 the owner of Pinenut mine found that 2.8 million gallons of water had accumulated in the mine shaft since it was put on standby in 1989.
  • In 2010, the USGS reported evidence that wind had dispersed uranium-rich dust offsite at three mined sites.
  • In 2016, uranium concentrations in soils near Pinenut Mine measured more than four times background levels, triggering additional dust control measures.
  • In 2017, Canyon Mine was issued a violation notice by state regulators for using giant hoses to spray water out of its containment pond that was overflowing due an influx of aquifer water flowing into the mine shaft.

Those violations bring up the question of what sorts of impacts should be expected and accepted in return for the benefits of mining, Bain said.

“There is a little bit of a cost of doing business,” Bain said. “You have to admit, mining is hard on the landscape. Is that a price you want to pay so you can have electricity and not live in a cave? It’s hard to say.”

Subscribe to Daily Headlines

* I understand and agree that registration on or use of this site constitutes agreement to its user agreement and privacy policy.

Emery Cowan can be reached at (928) 556-2250 or ecowan@azdailysun.com


Environment, Health and Science Reporter

Emery Cowan writes about science, health and the environment for the Arizona Daily Sun, covering everything from forest restoration to endangered species recovery efforts.

Load comments