The states of Washington and Oregon announced Thursday that they will sue the federal government if it continues to refuse to assess the environmental damage caused by decades of bomb making at the Hanford nuclear site in eastern Washington.

The states say that although the Department of Energy spends $2 billion a year to clean up its leaking plutonium factory beside the Columbia River, it has never done a thorough analysis of the harm that Hanford has done to groundwater, wildlife and fish.

The threat of a lawsuit marks a further deterioration in an already strained relationship between the Bush administration and the state of Washington, where most of the environmental damage from Hanford is centered.

"We find ourselves all too often with this administration being pushed into litigation," said Christine O. Gregoire, the attorney general in Washington and a Democratic candidate for governor. "We want to be a partner and we do not want to spend money on litigation, but we are being forced to."

The Department of Energy's assistant secretary for environmental management said she was "disappointed" by Gregoire's comments. "Frankly, I thought we were working pretty hard with the state," said Jessie Roberson, who oversees the Hanford cleanup and is leaving her position next week. "I can't believe they don't recognize how much progress we are making. Lawsuits don't get the work done."

Washington sued the Department of Energy last year to stop it from importing low-level radioactive material to the Hanford site from around the country.

Most recently, Gregoire said, the state has become alarmed by a federal decision regarding the highly contaminated, 80-square-mile plume of groundwater beneath Hanford.

In a recent administrative ruling, the Department of Energy decided that this plume of radioactive and chemically poisoned groundwater is "irreversible and irretrievable." Under the federal Superfund law, the language relieves the Energy Department of liability, if the contaminated water causes health or environmental damage outside the Hanford site, Gregoire said.

"For them now to propose walking away from their responsibility, we are not going to accept that," Gregoire said. "We are going to contest this record of decision regarding groundwater."

The groundwater plume, which has been slowly drifting toward the Columbia, abuts parts of the river and is threatening the water supply for Richland, where many scientists and bureaucrats employed in the Hanford cleanup live.

Hanford produced about two-thirds of the plutonium used in the Cold War. In the process, it generated the largest haul of high-level nuclear waste in the Western Hemisphere. Much of that is buried in 177 underground tanks, more than a third of which have been leaking for decades.

The Bush administration's stated goal is to keep these agents out of the Columbia River, while speeding up the cleanup, saving money and getting the federal government out of Hanford in three decades, rather than a previously projected seven.