Abig retirement wave seems likely to splash across the government during the 2008 to 2010 period, putting pressure on federal agencies to recruit talented workers and forecast the mix of skills needed for the next era of public service.

About 38 percent of the civil service is 51 or older, with a large cohort in the 55-to-59 age range. Many of these employees will become eligible to retire starting in 2008, data at the Office of Personnel Management show.

Warnings of a possible brain drain and loss of institutional experience have been sounded regularly by the Government Accountability Office, the congressional watchdog agency, and by federal personnel offices over the past five years. The Bush administration has put "human capital" strategies in its top management priorities since 2001 and hopes to avert staffing shortages that could weaken the delivery of government services.

Public opinion surveys, however, show that many college graduates do not see the federal government as one of their top employment options, and that has prompted some concern that agencies may find it difficult to recruit and fill critical jobs in law enforcement, health care, engineering and other fields in coming years.

Linda M. Springer, the OPM director, said federal agencies appear to be meeting the challenge of hiring young workers, noting that about a third of new hires in fiscal 2004 were under 30. But she added that a retirement surge in 2008 and a sizable loss of experienced hands could prove vexing for many agencies.

"Between now and then, agencies will need to work possibly a little extra hard . . . to capture institutional knowledge that that group will carry out with them," she said in an interview.

There's no way to predict, of course, how many employees will leave the government in the next few years. Retirement projections are tricky, in part because they involve individual decisions and are influenced by economic and other factors.

Springer noted that some civil service employees may have put their retirement plans on hold in recent years because they wanted to support the government's efforts to counter terrorist threats or because uneven returns in the stock market eroded their retirement investments.

Retirements were flat in 2001 and 2002 -- at 41,000 each year. They increased, Springer said, to 50,000 in 2003 and to 53,500 in 2004.

A look at the age distribution in government shows a graying workforce, with many employees able to qualify or soon qualify for standard retirement benefits at 55.

Of the more than 1.63 million civil service employees, more than 620,600 are 51 and older and more than 559,100 are between 41 and 50 years of age, fiscal 2004 data show.

That's more than 70 percent of the civil service.

In contrast, only 109,753 employees -- or 6.7 percent -- were younger than 30 in 2004.

OPM data show that the average age of full-time federal employees (not counting postal, intelligence and military personnel) is 46. That average has held steady since 2001 because agencies have modestly increased their hiring, with most of the recruits joining the government at an average age of 37, the data show.

(Despite the recent pickup in federal hiring, much of it for homeland security, the civil service is smaller than in past decades because of post-Cold War downsizing and Clinton administration staffing cuts. In 1994, for example, the government had nearly 1.8 million civil service workers.)

OPM's data suggest that agencies are trying to build up their workforces with younger people. Of the 84,549 new full-time hires in fiscal 2004, more than 25,600 were younger than 30 and an additional 26,000 fell between 30 and 40.

Springer noted that agencies appear to be using hiring "flexibilities" -- such as initiatives to bring in veterans and interns -- to help offset the recent increases in retirements. Of the 84,549 full-time hires in 2004, about 27,000 entered federal service through programs that used streamlined or specialized recruitment rules.

The government's ability to cope with a retirement surge, she said, probably will hinge on efforts by federal agencies to improve recruitment of young professionals and keep the workforce's overall average age of 46 from increasing.

If she could write a headline, Springer said, it would be:

"Good so far, but peak to come."

E-mail: barrs@washpost.com