If Reagan-style fine pruning of the federal establishment goes on long enough, this area could become a ghost town by the year 2010.

Through a combination of rifs, budget cuts and program shutdowns, the administration has been abolishing about 1,000 jobs a month here since the middle of last year.

Although fewer than 3,000 Washington area feds have been fired outright for economy reasons, a total of 21,629 U.S. jobs here were eliminated between January 1981 and last March. During the same period, 27,151 federal jobs were abolished in the rest of the nation.

Metro Washington's federal population, now believed to be below 340,000 (the official March head count was 345,051), now makes up about 12 percent of the total U.S. government work force which, in March, was 2.8 million and shrinking.

Defense agencies here are hiring, but the increased number of civilian workers taken on by the Army, Navy and Air Force is more than offset by cutbacks in domestic departments and agencies.

Outside of Defense, the agency with the fastest growth rate during the slim-down period was the U.S. Postal Service (up 8,000 employes nationwide since January 1981).

The figures for most other departments and agencies are on the minus side. For example, since January 1981 the Justice Department has lost 2,100 jobs; Interior has lost 5,600 jobs; Agriculture more than 7,700; Commerce 12,000 (many were temporary census workers); Labor 3,700; Health and Human Services 11,000; Housing and Urban Development 1,552 with more to come; Transportation 10,400; Energy 3,000 with more coming; Education 1,700.

Among independent agencies, the Environmental Protection Agency has cut 2,400 jobs; General Services Administration 5,400; International Communication Agency and the Nuclear Regulatory Commission both have added 240 jobs; Office of Personnel Management has cut 1,600 people; Panama Canal Commission added 95 people last year. Tennessee Valley Authority is down 6,600 workers and VA has cut 2,100 jobs.

The cutbacks are deceptive because some agencies have contracted out work formerly done by civilians and in some cases the contracting costs are higher than were federal salaries and fringe benefit costs.

During the same period, when civilian agencies were cutting jobs, the Defense Department added about 44,000 new employees nationwide. Army hired more than 20,000 people, Navy just over 11,500 and Air Force a little over 10,000 civilians.

The budget just approved by Congress calls for a reduction of about 20,000 federal jobs over the next couple of years, but those totals could increase if Congress and the White House insist on deeper program cuts.