But neither the Skull Valley Band of Goshutes, the Tooele County Indian tribe that promised reservation land for the storage, nor Private Fuel Storage, the nuclear-reactor operators that partnered with the Goshutes, were prepared to say Friday if, or how, they might fight the department's two-pronged decision killing the project.

"It will probably be a week before we have any real notion of what our next steps will be," said Sue Martin, a spokeswoman for PFS.

Deputies of Interior Secretary Dirk Kempthorne, the former Idaho governor and U.S. Senate Republican, issued twin rulings Thursday that appeared to deal a death blow to the multi-billion-dollar waste storage plan.

James E. Cason, associate deputy secretary for Indian affairs at the Interior Department, voided the 1997 lease between the Goshutes and PFS.

Chad Calvert, acting assistant secretary for land and minerals management, nixed the plan for transporting waste to the reservation, about 45 miles southwest of Salt Lake City.

Cason's decision noted the tribe had twice written letters last spring urging his agency to sign off on a "conditional lease" that was approved by a Utah-based Indian agency official more than nine years ago.

"The [Skull Valley] Band has also made numerous phone calls to Department officials demanding immediate action," Cason wrote.

The waste plan's critics - anti-nuclear activists, ordinary Utahns and state and federal officials - say the separate decisions kill the project. But PFS and the Goshutes were not ready Friday to concede.

PFS's Martin said Thursday's decisions leave the nation no answer to its nuclear waste backlog.

"The fact is, our facility was the closest, most immediate solution that was available to the [nuclear energy] industry," she said.

Lacking an off-site option like the Skull Valley storage, the nation's nuclear reactors have resorted to storing roughly 60,000 tons of high-level waste at 72 sites while they wait for the federal government to build the Yucca Mountain repository in Nevada, about 100 miles north of Las Vegas. The planned site is long past its deadline and is certain to be delayed for years to come. Congress has just begun to talk about creating federal interim storage sites.

Meanwhile, Dianne Nielson, director of the Utah Department of Environmental Quality, said her agency would continue its fight to kill the license the U.S. Nuclear Regulatory Commission granted to PFS in February.

She noted the Interior Department's rulings echoed many of the safety and legal concerns Utahns have been raising about the waste proposal for nearly a decade.

"The fact of the matter is they [at the Interior Department] did their homework," she said, "and I think they got it exactly right."

fahys@sltrib.com

Options for proponents of the Skull Valley nuclear storage site

* Call it quits.

* Fight the Interior Department's ruling in court.

* Propose a new lease and/or alternative transportation plans.