A company seeking to operate three uranium mines in northern Arizona has been denied a key state permit for two mines, near Tusayan and north of the Grand Canyon.

Amid field hearings and congressional legislation proposing to put the area around the Grand Canyon off-limits to uranium mining, this is the first real roadblock to the first proposed uranium mining in Arizona in this decade.

The Arizona Department of Environmental Quality said Denison Mines proposed using outdated, 20-year-old liners and impoundment ponds to capture uranium mine-related runoff. In addition, ADEQ said Denison wasn't specific enough in describing pollution-control measures at the proposed mines.

On those grounds, the agency denied a general permit for the mining company last month, asking it to apply for more specific, rigorous permits.

"The burden is on them to prove to us that there will not be an impact on groundwater," ADEQ Director Steve Owens said.

More detailed permits are the norm for most mines around the state.

Denison Mines, owner of a uranium mill in southeast Utah, has proposed opening the Canyon Mine, located between Tusayan and Valle, near Red Butte, and reopening the Pinenut Mine near Kanab Creek and Hack Canyon, along the Kanab Plateau.

Both of these sites were denied permits by ADEQ.

The Canyon Mine was the site of a long legal battle, opposed for mining by the Havasupai Tribe.

The tribe lost that court battle, but owner International Uranium Corporation put mining on hold until uranium prices rebounded. There is equipment on the site, but it has never been mined.

Another uranium mine southwest of Fredonia is proposed to open this year, said Ron F. Hochstein, president and chief operating officer for Denison, and that plan is moving along without organized opposition.

Combined, the company projects the three mines hold about 239,000 tons of uranium ore.

Denison owns five other uranium deposits on the Arizona Strip, as one of numerous claim-holding companies.

Hochstein didn't know why the company's permit had been denied, he said.

"We have an opportunity to appeal," he said. "We're in the process right now of looking at what our options are."

Uranium prices are now higher than they have been since the 1950s, and have hit more than $100 per pound this year.

There are estimated to be hundreds of vertical columns of uranium, known as breccia pipes, on the Colorado Plateau, including 900 pipes on Hualapai land, according to an assessment by the Arizona Department of Mines and Mineral Resources.

One U.S. Geological Survey estimate put the number of uranium-bearing pipes at about 1,200 on the Colorado Plateau.

There are also new means for detecting previously undiscovered uranium deposits, according to the mining department.

Local scientists, including Northern Arizona University geologist Abe Springer, have raised questions about whether uranium mining could affect seeps in springs in the Grand Canyon. They say they don't know the answers.

ADEQ is proposing to study the site of any proposed mine for such data.

"We have to be satisfied that the operations there can be conducted safely, without the risk of contamination to the aquifer," Owens said.

Cyndy Cole can be reached at 913-8607 or at ccole@azdailysun.com.