Pink slips went out Monday to nearly 250 workers and more than 2,500 others were notified that they face furloughs of several weeks at the nation’s most contaminated nuclear site, where cleanup is likely to be slowed because of automatic federal budget cuts.

About 9,000 people work at south-central Washington’s Hanford Nuclear Reservation, which produced plutonium for the U.S. nuclear weapons arsenal beginning in World War II and through the Cold War.

Several contractors are digging up contaminated debris and soil, tearing down buildings and mothballing nuclear reactors, treating contaminated groundwater, and removing millions of gallons of radioactive waste from underground tanks for treatment at a plant under construction there.

The plant’s construction will not be affected by the budget cuts, because the plant maintains an annual budget of $690 million for design and construction, said Todd Nelson, a spokesman for Bechtel National Inc., the company building the plant.

All other work at the site is likely to be slowed, though it’s yet to be seen whether any cleanup deadlines will be missed.

The layoffs will largely affect union employees who practice a particular trade, such as pipefitters, the Energy Department said. The furloughs will target nonunion office workers, including administrative, engineering and safety professionals at the Hanford site and at offices in nearby Richland, Wash.

Central to cleaning up Hanford is the removal of millions of gallons of toxic, radioactive waste from underground tanks. State and federal officials recently announced that six tanks there are leaking, raising concerns about any delays to emptying them.

The layoffs and furloughs are occurring “at precisely the wrong time,” Washington Gov. Jay Inslee said Monday.

“These lost jobs and work hours will adversely impact families in the Tri-Cities and will harm economic recovery in the region,” he said. “Now is no time to scale back federal commitments to protecting public and environmental health in our state.”

The federal government created Hanford in the 1940s as part of the top-secret Manhattan Project to build the atomic bomb. Today, it is the nation’s most contaminated cleanup site, with the cleanup effort expected to last decades.

The Department of Energy’s Office of River Protection, which oversees tank cleanup and plant construction, said its budget had been cut by $92 million. That money will largely come from tank cleanup, because of the fixed budget for the plant.

Washington River Protection Solutions, the company tasked with emptying those tanks, notified 37 union employees that they were being laid off Monday, company spokesman Jerry Holloway said. Another 33 union workers are expected to be bumped by more senior workers from other Hanford contractors, he said.

Nuclear operators, who move waste between tanks and pump it out, are among those hardest hit, he said.

In addition, Holloway said the company’s roughly 900 nonunion employees will be furloughed for varying lengths, ranging from 2 1/2 to 6 1/2 weeks.

Federal officials have proposed a plan to ship waste from five of the six leaking tanks to New Mexico. However, that proposal will take at least two years as the federal government seeks necessary permits.

For that reason, Holloway said, the layoffs and furloughs will not affect the leaking tanks.

Work to evaluate the leaking tanks and to inspect other tanks will continue, he said.

The Energy Department’s Richland Operations Office said its budget will be reduced by $79 million. That office oversees three contractors and numerous subcontractors responsible for cleaning up the Columbia River corridor, tearing down buildings, mothballing nuclear reactors, treating groundwater and digging up contaminated debris and soil.

Agency spokesman Cameron Hardy said more than 200 employees will be laid off from those three contractors, and more than 1,700 employees will be furloughed for about five weeks.

The U.S. government spends some $2 billion each year on cleanup at Hanford. That’s one-third of its entire budget for nuclear cleanup nationally.

The cuts within the Energy Department’s budget are the result of debate in Congress, where Republicans and President Barack Obama are fighting over how to curtail the nation’s debt.