Idaho Department of Labor spokesman Will Jenson said about 25 percent of eastern Idaho's workforce is employed at the site.
Battelle Energy Alliance said employees can use personal leave to get paid during the curtailment.
"I understand how disruptive this curtailment will be to many of you and your families," Idaho National Laboratory Director John Grossenbacher said in a memo to workers. "I am confident that we are responding appropriately and have an executable plan to return to work as soon as adequate funds are available."
Idaho Cleanup Project workers are managed by CH2M-WG Idaho LLC, also known as CWI. The company has been working to clean up waste from nuclear energy research, World War II-era weapons testing, and spent fuel processing.
Battelle and CWI employees will not be eligible for back pay, officials said.
Rep. Mike Simpson, R-Idaho, said he hoped the situation would force an agreement to reopen the government. He said he could support a continuing resolution to do that without linking it to the Affordable Care Act for a short time, possibly two weeks.
"I could support a very short-term clean continuing resolution ... while we continue to negotiate on a longer-term bill that addresses priorities we believe are important," he said.
Information from: Post Register, http://www.postregister.com