Walter E. Washington, the District of Columbia's first elected-and now first defeated-mayor in a century, steps down Tuesday, his 11-year career an incongrous mix of tumult, chnge and motionlessness.

Last week, Washington, dressed in a crisply tailored three-piece suit, leaned back in his office chair and pondered the good times and the bad in thos 11 years.

"You can Monday morning quarter back anything and can always look back and say I should've done something differently or better," he said, ". . . but in the balance, I think I brought the city forward."

Walter Edward Washington- the mayor who walked the streets when the city was in flames in the 1968 riots, who called for unity, restraint and accommodation during the convulsive antiwar years, who viewed himself as a healer of wounds, a bridger of gaps-was rejected in his bid for reelection, his once broad-based constitutency severely eroded.

His peacemaker role was eclipsed by increasing public perception of his mammoth 35,000 employe bureaucracy as muscle-bound and unresponsive.

There were those who said his time has passed, that once the dramatic crises he handled so well in the late 1960s and early 1970s were behind him and he had to ccontend with the hard daily realities of running a large,city Walter Washington foundered.

His bureaucracy had become a sleeping giant. He used no whips to goad it, and his soft peacemaker's voice was not enough to move it.

At age 63, with 36 years of District government service behind him Washington says he feels "some desappointment" at his rejection at the polls last fall. But the "mark of a pro," he said, "is to go ahead and do the things you think are right and work to make the transition (to the new administration of Mayor-elect Marion Barry) as smooth as possible."

In the rambling hour-ling interview last week, Washington brushed aside critical Barry task force reports that say Bary is inheriting an inefficient and almost chaotic government machine encumbered with inccompetent personnel, irrational planning and massive backlogs.

"We've got urban problems like other cities, sure, and they're not all solvable immediately," he said, ". . . yet I feel that in most of the program areas, we've improved."

Among specific improvements, he said, are expansion of welfare services to long neglected poor areas east of the Anacostia River, major reductions in reported street crime and an upsurge in downtown building construction.

"I'm also leaving a $40 million suplus in the treasury, which is a little unusual these days," he said dryly in reference to financially strapped cities like Cleveland and New York.

In interviews with former and present officials and aides, Washington was portrayed repeatedly as a man who "set a tone. . . created an atmosphere," a man remembered not so much for specific acts as for providing an environment for the actions of others.

Some say he was a safe, compromise mayor, the only man then-president Lyndon B. Johnson could install in the racially polarized period of the mid-1960s-a canny but old line black government careerist with acceptability in both black and white worlds.

"A lot of people have been involved in improving the city," said John R. Risher, former corporation counsel and a close adviser to Washington, "but he was the visible leader."

His image suffered at the hands of the news media, however, said Risher, because of his meandering speech and bureaucratese-his "bottom lines" and "programatic thrusts"-and he often ended up looking like a "cornered man fighting for survival."

But "he was an extraordinary leader who loved this city," Risher said.

Nevertheless, Washington's critics say he left the city with many serious ailments. Infant mortality and key disease rates such as those for cirrhosis, tuberculosis and veneral disease are among the highest in the nation. Municipal elections-which came to the city only after Washigton was appointed mayor in 1967 by Johnson-have meen periodically plagued by errors, delays and assorted snafus. At least three city facilities-D.C. jail, D.C. General Hospital and Forest Haven, the city's institution for the mentally retarded-have been under continuing court orders to meet various minimum operating standards.

"We're almost operating by court decree," said Barry at a recent press conference.

The depth and range of problems were "greater than we had anticipated," says Delano Lewis, chairman of Barry's transition committee.

"There are 159 boards and commissions in this city," said Lewis, "and we don't even know the names of about 70 of them, let alone the members of them . . . We thought there was a computer run on them, but we can't get a handle on them."

Washington's 11-year career as mayor also spanned a time of massive demographic change in the city. The white flight of the 1960s ended and in some areas reversed itself while blacks began a steady outflow to the suburbs, especially to the east of the city.

Many black critics see this as a concomitant to the city's celebrate economic revival, with its double-edged effect of uprooting black families and atomizing what was becoming an urban black power base. Some blacks see Washinton as an unwittin pawn in this process.

Hanging over Walter Washington's career also has been the nae of Joseph P. Yeldell, the city's former health and welfare agency chief. A flamboyant loyalist and confidant of Washington, Yeldell was convicted eartycoon Dominic F. Antonelli Jr. A new trial order issued recently in the case is now under appeal.

"Yeldell was decisive in Walter's defeat," says one high-ranking government official close to the mayor. Washington refused to discuss Yeldell in an interview, citing the fact that Yeldell's case is still under litigation.

Several present and former city officials who have been close to Washington over the years say he resisted frequent temptation to be confrontational and abrasive in political dealings during the turbulent years of riots and demonstrations here.

"In a way, it may have helped cause his defeat," said another. "The very fact that he did not speak out and call senators "rinky-dink" when people in the city were calling on him to speak out for them-that cost him a lot of votes."

"Walter Washington in his own way pushed the system ot accomplish the things he believed in," the officials said.". . .But I think underneath this was a philosophy that there are limits to what you can do this way-that if you push the system too hard, it will flare back at you. . . To that entent, he may have had some failures and shortcomings."

But there were also the successes. It was Walter Washington the peacemaker, the accommodator, his supporters say, who imposed restraint on the police in handling rioters and demonstratros, allayed the fears of jittery businessmen in the inner city and defused explosive confrontations between members of Congress and his own department chiefs.

Barely five months after he was appointed mayor of the city in November 1967, the streets exploded in riots with assassination of civil rights leader Martin Luther King.

Washington imposed a strict "don't shoot the looter" policy on police. The result: two people were shot and killed by police here while dozens were shot in other cities.

The city had become so sharply polarized on the incidence of white police shooting black criminals suspects that some black leaders called the shooting of police "justifiable homicide" and demanded greater discipline of officers.

Washington's reaction: he instituted a policy of placing officers involved in shootings on administrative leavr with pay. It provided a cooling-off period, an official said, and at the same time satisfied the black community by taking the cop off the street but gave the cop his dignity by letting him keep his pay."

In the same way, Washington set a tone of restraint in handling the mass antiwar demonstrations of the late 1960s and early 1970s.

On one occasion, when the Justice Department flatly refused to permit the New Mobilicaion Committee to End the War In Vietnam to lead thousands of demonstrators in a march up Pennsylvania Anenue on Nov. 15, 1969, Washington went to the White House and directly appealed to then-president Richard M. Nixon to reverse the Justice Department to prevent a possible violent blackash in the city. Hours later, a permit was granted. An estimated 250,000 was protesters marched without incident.

"Without his moderating influence the demonstrators would have been handled here the way the shah is handling demonstrators in Tenran now," one mayoral aide said.

Many officials close to Washington and Washington himself said in interviews that a chief motive for his tactics of accommodation, rather than confrontation, was to limit pretexts for critics to discredit the District's new black government.

"If the (mass antiwar demonstrations) had been successful in really distrupting the city, for example," said one official," we never would have the home rule.

He was concerned that since this was a new inexperienced government, some people might be insensitive to the fact that any mistakes it made would not be uniquely black phenomenon," said Risher.

R. Robert Linowes, immediate past president of the Metropolitan Washington Board of Trade, praised Washington for his role in the present economic upturn in parts of the city.

"In his own style, he created a feeling that Washington is not a dead city, that its' going to overcome its problems and rebound," Linowes said.

A recent Board of Trade study shows that 34 major building projects worth more than $1.3 billion and generating up to 23,000 permanent jobs are planned for the downtown area alone.

As Washington bows out, he says he sees six major items on the District's unfinished agenda: ratification of the full representation amendment, anactment of a commuter tax, exclusive control by the city over its budget, an "assured and predictable federal payment," increased housing production and "continued strengthening of the economic climate."

Asked about his own plans for the ftuure, he said he was "talked to a lot of people. . .but it's too early to say anything right now."

Born in rural Georgia and raised in upstate New York, Washington came to the District in the Depression years and graduated from Howard University. His career in government service began in 1941 when he became an administrative intern with the old National Capital Housing Authority. He rose through thr NCHA ranks, picking up a law degree at Howard University along the way, and was NCHA director for five years before he was appointed mayor of the city in 1967. The years since then are history.

"What I would like to be remembered for," he said last week, "is that Walter Washington changed the spirit of the people jof this city, that he came in as mayor when there was hate and greed and misunderstanding among our people and the races were polarized. . . and in the span of just little over a decade he had brought people together through love and compassion, he had helped bring about home ruled. . . and had helped people have more meaningful, satisfying and enjoyable lives." CAPTION: Picture 1, WALTER E. WASHINGTON . . . "I brought the city forward"; Picture 2, Washington meets with President Johnson in 1967 when Johnson announced Washington's appointment as mayor. The Washington Post