The rumors of job terminations had been circulating in his office for weeks, but it wasn't until May 20 that Denzel Fisher, a grants administrator at the U.S. Water Resources Council, finally took them to heart.

That's the day Fisher and the rest of the federal workers at the small water planning agency were told -- in a blunt, written alert -- that their government paychecks would stop as of Sept. 30.

"The psychological impact of it all really hit me," said Fisher 36. "When you finally see things in black and white, then you know. We've kept busy here, but it's rather hard to be enthusiastic about functions you know are going to be terminated."

Barring a change of heart or circumstances in Congress, the Reagan administration's cutbacks in federal funds and jobs will likely force nearly 15,000 nonmilitary government workers like Fisher to start job hunting. In the Washington area, once thought to be a fire-proof federal enclave, the scope of job losses will be unprecedented, with some 4,450 employes expected to be scrambling for new work by the end of the summer.

About 650 layoffs, dubbed "reduction in force (RIF) separations" in bureaucratic lingo, have already occurred. For now, government workers outside this huge federal stronghold have been the hardest hit.

But this region will feel the job crunch in July and August, and with it a sweeping and complicated employment shake-up that will affect many of the 366,000 civil servants who work for the area's biggest company -- the U.S. government.

"It ripples through the whole system, and there is a domino effect, but many agencies haven't gone through this dance before," explained Claudia Cooley, who chairs the Office of Personnel Management's task force on personnel reductions in the government. "A lot of employes are anxious and upset because they know their agencies are making contingency plans."

A central problem, according to government officials, is that Washington has never had to reduce its federal work force to the degree now being required. Some agencies, ordered to cut staffs, are trying to decide what and who they need to keep functioning. Other agencies are being abolished outright, which, in a sense, makes the process easier for personnel officers because, "Everybody goes" -- in some cases workers with 15 years or more of service.

"Most of the RIFs in the past have occurred elsewhere," said Cooley, whose office is working with all federal departments to help displaced workers find new jobs with the government or private employers. "This is unfamiliar to Washington and non-Defense personnel and accounts for the high level of anxiety."

No one is more anxious than a federal worker who has gotten marching orders, particularly if there is a family to support and mortgage payments to meet. But being uncertain about your fate is almost as bad.

"It's been just like death around here, like we have a terminal disease," said Betty Lee, a program analyst with the Alcohol, Drug Abuse and Mental Health Administration -- a division of the Health and Human Services Department -- which is anticipating RIFs of 25 percent of its staff.

Lee, who has spent the last three of her eight years in government service working for the alcohol and drug agency, has updated her government resume -- known as a Standard Form-171 -- and is waiting to see what happens. She recently married, reasoning, "I had to have some good news."

One Water Resources Council worker, Marilyn Landry, 32, wasn't willing to wait for the ax. She quit yesterday so she could "devote full time looking for a job."

At this point, nearly all federal employes have been told whether to expect their job positions to be abolished. But most don't yet know whether their "retention rights" -- a term describing complex job preference rankings based on seniority, veterans status and job classification -- will enable them to survive the coming shake-up.

For a real sense of the future, government workers must know how many of their colleagues are above them and below them and whether they will be vulnerable to, or can take advantage of, such federal rituals as "displacement," "bumping" and "retreating," government jargon for the chain reaction that is set in motion whenever a RIF is in the works.

"They take the lowest persons on the government's totem pole and RIF them," said Sharon Scott, a secretary in the radiation program branch of the Environmental Protection Agency. Although her office, and her postion, have remained largley intact, Scott is waiting to see if she gets "bumped" out of a job by another, higher ranked, secretary who may have been "displaced" elsewhere in the agency and had to come looking for a new spot.

"I know my position is safe, but I don't know if I'm safe," said Scott.

The majority of layoffs are affecting mid-level bureaucrats and skilled professionals, people who will find the competition fierce when they look for new jobs; the only secretaries and lower level workers hit by the job squeeze are those in agencies where entire branches have been abolished. But the process for all level of RIFfed employes is the same.

"It's just so complicated," acknowledged Jim Murray, deputy personnel director of the Health Services Administration headquarters at the Parklawn complex in Rockville. That agency is under orders to shut down eight Public Health Service hospitals around the country and cut back on staff at the Bureau of Community Health Service. The moves could eliminate jobs for nearly 6,000 federal workers in the regions and about 350 here, and Murray's office is busy at the moment juggling around those who will survive and trying to find other jobs for those who won't.

In RIF situations, agencies first figure out which jobs will be abolished and which will remain, and then sort out retention rights. A veteran with 30 percent or more disability, for example, would rank near the top of any retention list. Someone with less than three years government service would be ranked near the bottom. Veterans with little or no disability would rank second highest, followed by nonveterans.Each of these various subgrouping of workers would also be ranked according to length of service.

Murray, who keeps it all straight by referring to seemingly incomprehensible diagrams of hypothetical RIF situations, stressed that employes are only entitled to the highest graded jobs for which they are qualified. They can't displace those in a higher classification.

"You always go to the bottom of the list -- you displace, then bump to the lowest level." Employes who are bumped from their jobs have two options: they may try to bump a lower ranked employe or they may try to "retreat" back into a lower grade level in a position from which they were promoted.

If you are displaced, and you can't or don't want to bump someone else or retreat into a lower level, the final result is "separation," or layoff.

When the process is done -- "and we don't really know all the ramifications until we have finished" -- employes are given specific notices telling them who must go, who can stay and under what conditions. Most people, Murray said, want to wait and see "what they're offered first. But if you have any sense and realize ther's going to be a 50 percent reduction and you've only been at the agency a short time, you might as well start looking."

To help their employes "start looking," personnel offices in the various agencies have begun coordination job vacancy information and establishing contacts with each other as well as with chambers of commerce and nearby local and state governments. Some agencies have held seminars on how to prepare government resumes and go job-hunting, and other agencies have hired outside experts who have held workshops for nervous "federal Freddies" on how to put their best foot forward in an increasingly competitive market.

Giving job-hunting aid is particularly bittersweet for personnel officers at agencies targeted for extinction; they are pounding the pavement along with everybody else.

Some of the federal workers affected are more panicky about their employment chances than others. A hydrologist at the 61-person Water Resources Council, who is Chinese and speaks little English, just lined up another job at the U.S. Geological Survey because his skills are so marketable. But a grants administrator at the same agency is concerned about his own chances during a period when government-controlled grants "are out of favor."

At the Community Services Administration -- the beleaguered vestige of Lyndon Johnson's War on Poverty -- systems analyst Bill Johnson and legislative affairs officer Christina Rossomando are among 950 employes whose jobs are soon expected to be as extinct as the agency. Jackson, 54, has been with the agency since it started 15 years ago, and is reluctantly making the rounds of other agencies "because I need a job"; Rossomando, 27, is leaving after 3 1/2 years.

"I really like this program, and I don't want any other government job," said Rossomando. Single, she has few of the financial obligations that will burden RIFfed federal workers with children and mortgages. Still, "my severance will only last me three weeks, and I just lost my apartment and had to move into a more expensive one, so this is not a good time to be losing my job."