Washington (CNN) -- Nearly 800,000 civilian workers would be forced to take one day of leave per week without pay if automatic spending cuts go into effect as scheduled, the Defense Department told Congress on Wednesday.
The furloughs would start in the last week of April and last for 22 weeks, according to the Pentagon plan, and would hit the hardest in Virginia, California, Maryland, Texas and Georgia, where many defense facilities are located, according to figures provided by the Pentagon.
The plan responds to mandatory, government-wide budget cuts, known as sequestration, that are due to begin on March 1 absent congressional action on deficit-reduction to avert them.
Furloughs would eat up between $4 and $5 billion. Pentagon cuts overall would comprise half of the government-wide sequester of $85 billion for the fiscal year ending September 30.
"In the event of sequestration we will do everything we can to be able to continue to perform our core mission of providing for the security of the United States, but there is no mistaking that the rigid nature of the cuts forced upon this department, and their scale, will result in a serious erosion of readiness across the force," Defense Secretary Leon Panetta said in a letter to Congress on Wednesday.
The Pentagon would also have to reduce numerous weapons and training programs across all services.
"We feel we don't have any choice to impose furloughs even though we would much prefer not to do it," Pentagon Comptroller Robert Hale told a media briefing.
Furloughed workers could include office staff, aircraft and ship maintenance workers, teachers and medical staff.
But Hale said Defense Department civilian foreign employees would be exempted from pay cuts. There are about 50,000 foreign worker employees overseas employed on U.S. military facilities.
"They're governed by status-of-forces agreements and probably would require some negotiation," Hale said.
Other employees exempted would include civilians working for the agency in combat zones and certain emergency and safety personnel. Presidential appointees would also be exempt from furloughs.
The military services and other defense agencies will have to maintain at least minimum staffing for the "safety of property and safety of life," Defense Department spokeswoman Lt. Col. Elizabeth Robbins said.
That means, for example, a military base would have to maintain a minimum force of security personnel.
Similarly, military hospitals must have enough medical staff to provide services to active-duty personnel, including the wounded.
Hale told reporters that the economic impact would be felt nationwide, not just in the Washington area, where many defense department jobs are located.
For federal workers, it will mean painful decisions, said Defense Department Peter Randazzo, who is also a union representative.
"I'll pay those core bills. I'll pay the mortgage and the utilities and then you live on what's left," he said.
The armed services, Wednesday, also notified Congress of the potential impact of budget cuts to states.
The Army and Navy are circulating estimates about which areas will be economically hit the hardest.
In documents sent to Congress and obtained by CNN, both the Army and Navy lay out the potential impact on the services and industry.
For the Army, the hardest hit states include Texas, Virginia and Pennsylvania, home to major Army facilities and industrial bases.
The Army anticipates it will need to slash $18 billion in spending by the end of the fiscal year.
If the spending cuts are carried out, the Army would be required to furlough 251,000 civilian employees. It estimates that would save it $1.9 billion.
The Navy anticipates it will need to slash about $12 billion in spending. The impact would affect more than 300,000 sailors with cuts to Navy operational programs and cost some 186,000 Navy civilians 20 percent of their paychecks though furloughs, saving about $500 million, according to Navy officials.