After a lengthy and contentious approval process, Colorado on Thursday granted a license for construction to begin on the first new uranium mill in the U.S. in more than 30 years.

The Colorado Department of Public Health and Environment issued Toronto-based Energy Fuels a radioactive materials license, clearing the way for the creation of the Pinon Ridge Mill in western Colorado’s Montrose County.

Pinon Ridge will transform uranium ore from mines into uranium oxide, which will be sent out of state to be turned into fuel for nuclear reactors.

That doesn’t mean construction is imminent. Energy Fuels spokesman Curtis Moore said the company is waiting for the price of uranium to rise. Currently, Moore said, uranium is priced at about $40 per pound, down from about $72 per pound before the disaster at Japan’s Fukushima Plant in 2011.

The spot price of uranium was more than $135 a pound when Energy Fuels announced plans for the mill in 2007.

The Pinon Ridge Mill is expected to process 500 tons a day of uranium and vanadium, which is used in steel alloys and high-tech batteries. The mill will primarily process ore from mines in Gateway, Colo., and La Sal, Utah, according to CDPHE documents.

Energy Fuels also plans to open or reopen a number of Colorado mines, Moore said. Those mines are all small — perhaps a few hundred acres in size — and are mostly in areas that have been mined previously.

“These are historic mines, historic mining districts. These are not pristine wilderness districts,” Moore said.

Colorado originally authorized the mill in 2011, but the decision prompted appeals from a handful of activist groups. A Denver judge eventually invalidated that license after finding that the state did not hold formal public hearings.

This time around, the state hosted a six-day hearing to allow for public comment and cross-examination of witnesses. But at least one of the groups that protested the decision in 2011 is still wary of the proposed mill.

“It appears the state did not take into consideration all the evidence presented at the hearing, and they went ahead and issued the same decision documents,” said, Hilary Cooper, executive director of the Sheep Mountain Alliance, the grassroots organization that spearheaded opposition to the initial license decision.

Cooper said she is still reviewing the decision from CDPHE but hasn’t ruled out appealing parts of it. She is especially concerned about what she says are “encouraging words for why they want a radioactive waste dump there and how it would help the state.”

Warren Smith, community involvement manager for the Hazardous Materials and Waste Management Division of CDPHE, said importing radioactive waste is not allowed under the license. He notes that waste produced by the mill will be stored in underground cells designed to last at least 200 years.

The license carries a number of other environmental safeguards, including requirements that Energy Fuels monitor groundwater for contamination and install fences and wires to keep wildlife away from areas that might have radiation.

The license itself is subject to periodic review and must be renewed whenever there is a change to operation procedures or key personnel. Additionally, the CDPHE plans to designate at least one staff member whose priority will be monitoring and inspecting the mill.

Montrose County Commission David White said that most area residents seem assured that the plan is environmentally sound and are excited about the economic possibilities. Once constructed, the mill is expected to create at least 85 jobs, with up to 400 jobs generated by opening additional mines and increasing economic activity, according to Moore.

CDPHE’s environmental analysis also notes that 88 percent of the land within five miles of the proposed site is undeveloped and administered by the U.S. Bureau of Land Management.