WASHINGTON — And then there were four.

Entergy Corporation, one of the eight original investors in Private Fuel Storage, will hold future investments from the proposed nuclear waste storage site, Executive Vice President Curt Herbert Jr., told Sen. Orrin Hatch, R-Utah, in a letter sent Tuesday.

Entergy becomes the fourth PFS investor this month to change its financial support, which on top of other recent legislative and administrative action, has "put Utah over the hump in our fight against the Skull Valley plan," Hatch said.

Herbert wrote that Entergy will withhold future investments in Private Fuel Storage "as long as there is apparent and continuing progress toward federally sponsored away-from-reactor storage and disposal for the nation's spent nuclear fuel."

Entergy owns the second-largest fleet of nuclear plants in the country.

"We recognize the political obstacles to finding solutions to management of spent fuel from nuclear plants and believe the Utah facility is probably not the best solution to be pursued at this time," Herbert wrote.

The letter is similar to those written by Xcel Energy, Southern Company and Florida Power and Light, all who have changed their financial backing of the proposed used fuel storage site at the Goshute's Skull Valley reservation in Tooele County.

Xcel, which holds the largest percentage of the consortium, said it will put a hold on its funding while Southern and FPL have opted out completely.

PFS spokeswoman Sue Martin said not to read too much into the companies' decisions. The site was always going to be done in phases, and there are a lot of other companies out there who have storage needs that could sign on in the future to move the project to its next stage, she said.

The companies seem to have a renewed faith in the government's plan to store nuclear waste in a permanent repository at Yucca Mountain, 90 miles northwest of Las Vegas. This is puzzling at first glance because the companies created the idea of PFS in the first place because Yucca was not going to open on time and the project still faces a variety of obstacles before it would open — which at the earliest could be 2012 to 2015.

"When PFS was proposed, they looked at it as an insurance policy," said A. David Rossin, a former president of the American Nuclear Society and a former Assistant Secretary for Nuclear Energy at the Energy Department. "I don't think they expected as many political problems."

Rossin said prospects for Yucca sometimes look better and sometimes looks worse.