David Tatel was a young law student in the racially torn Chicago of the late 1960s. Swept up in the civil rights movement, he prowled the streets of the South Side, collecting evidence and growing outraged at the injustice he saw.

A decade later, Tatel, the departing head of the Office for Civil Rights of the Department of Health, Education and Welfare, has revitalized the government's troubled enforcement agency and aimed its full might back on those scenes like a water hose.

It is Tatel, though blind as the result of a progressive disease, who has been the driving force behind the government's revived determination to take whatever steps are necessary -- including busing -- to desegregate Chicago's schools. It is one of the toughest and most politically explosive of such enforcement actions ever undertaken.

Tatel is leaving the exhausting demands of his post, he says, to return to the law firm of Hogan and Hartson here. Yesterday was his last day at HEW. Though he will continue his interest in civil rights and pro bono work, he plans to practice general civil law.

To some critics, Tatel represents the sort of rigid zeal that grew obsolete as the civil rights movement traveled up the Mississippi, like jazz, into northern complications. They say he suffers from the bureaucratic impulse which one columnist called "terminal earnestness."

Tatel is "regulating for the '80s with a 1950 mentality," said Dr. Joseph Hannon, Chicago school superintendent, though he praised the man personally as a "tireless guy."

To his supporters in the civil rights community, Tatel is a model of incredible perseverance, a man who combines idealism with hard practical skills.

"People in Chicago are fond of saying this [desegregation suit] is being done by people who don't know what they're doing," Tatel said recently as he prepared to leave. "But Patricia Harris went to Chicago public schools. My wife taught at a black school on the South Side. And 200 people in our regional office have their kids in school there."

Tatel's own children are in public schools, and one is bused, but he contends that is irrelevant.

"He has been the conscience and the spearhead of intergration," said veteran civil rights warrior and attorney Joseph L. Rauh Jr. "He's going to be a damn hard act to follow."

It was Tatel's constant backstage pushing to desegregate the University of North Carolina and the resulting political fallout which helped move President Carter to fire HEW Secretary Joseph A. Califano Jr. last July, Rauh and other contend.

And it may have been his refusal to dodge controversy which contributed in part to the sharp and embarrassing rebuke to him by the new HEW secretary, Patricia Harris, a couple of weeks later. Some who witnessed the incident said that Harris had stressed the need to move with some "political sensitivity" in cases such as Chicago.

But Harris expressed "regret" at his resignation and praised his "commendable skill, resolution and equanimity . . . under difficult circumstances."

Charles Rangel, the black congressman from Harlem, who has battled Califano and Tatel over what he considered bureaucratic foot-dragging on civil rights, called Tatel a "fantastic individual. He has put the Office of Civil Rights back on its feet . . . He's very, very professional.

Tatel's coworkers describe him as a skilled organizer and a "demanding perfectionist" who works long hours and who, when some people's work isn't up to snuff, does it over for them.

He is also a devoted family man -- another reason he's leaving his post -- who often babysits one or more of his four young children at the office. Once, a Tatel offspring reportedly defused a potentially explosive civil rights confrontation.

Califano and Tatel were locked in their meeting with the leaders of the women's movement since taking office, late one afternoon, and things were very tense. Then, the story goes,Tatel's wife dropped off their 14-month-old daughter for him to babysit. When she suddenly plopped the baby and diaper bag into Tatel's lap, the group broke into applause.

As for the blindness, which became total five years ago, Tatel dismisses it as "just a nuisance."

He digests the large quantities of reading material that go with his work with the help of a college-student employe who reads aloud to him. He has developed a remarkable memory, aides say, which enables him to cite a certain passage in a complicated legal brief, or to organize a project without putting anything on paper. At home, he "reads" Talking Books from the Library of Congress, on tapes of discs.

He relieves the frustrations of his work by running almost every day, with friends alongside to guide him, and he runs in the Marine marathons here. He also skis.

Some people have extensive dealings with him without realizing he can't see.

"He had come to my office twice before he took over OCR and I had no idea he was blind," Rauh recalled.

Tatel can still "see" vividly those children in segregated Chicago classrooms.

"It was my experience in Chicago, seeing the racial polarization . . . that was really the basis for all the civil rights work I've done since then," he said in a recent interview.

That career has included stints as director of both the Chicago and the National Lawyers Committee for Civil Rights, and while he was a partner in Hogan and Hartson, a successful defense of the NAACP in a famous $1.2 million legal dispute with a group of Fort Gibson, Miss., merchants.

When Tatel came to OCR 2 1/2 years ago, he found it, by all accounts, in disarray after neglect in the Nixon years.

In 30 months under Tatel, the staff doubled, from 850 to 1,700. Among other things, his staff reduced a back log of 3,200 complaints to zero and has kept them current, even though the number of complaints coming in has tripled, according to aide Colleen O'Connor.

Federal civil rights enforcers these days race a tightrope walk between boldness, which could provoke conflicts with public officials such as Chicago Mayor Jane Byrne that would damage Carter's reelection prospects, and timidity, which could get the administration in trouble with its black supporters.

Despite all the political restrictions and the sheer unwieldiness of the bureaucracy, Tatel said, one's power to bring about change is much greater inside than out of government.

"But only if your office is well-managed and has well-trained people. That's why we spent the first two years working on that . . . These management improvements will not walk out the door with me."

He refused to discuss his public dressing-down by Harris. Witnesses to the incident said Harris told Tatel that two briefing books prepared by him were sloppy and inadequate, and lacked an index, executive summary and table of contents. Some who were present contend that the books did contain these items.

Some staff members attributed the incident to Harris' brusque and direct manner and not to a retreat on the issues. Tatel said that he still has no doubt that Harris, who is black, is firmly committed to the cause of civil rights.

On the subject of political pressures, Tatel said, "In the long run, the people who are protected by [civil rights laws] are not represented at all in the political process, or are underrepresented. If you are affected or controlled by political considerations, what you are doing is erasing these statutes."

On the other hand, the negative effects can be minimized, he said, by "keeping local officials informed and being honest with them."

In being flexible, he said, "The question is how much less [than a perfect remedy] do you accept in order to get those children into integrated classrooms now, instead of waiting through 10 years of litigation."

Accusations of overzealousness anger him. "People don't seem to understand," he said. "Congress passed those laws. Congress passes laws which are popular in the abstract . . . and then tosses them to the bureaucrats" to interpret and put into effect somehow.

He conceded that some bureaucratic actions do go too far. But generally, he said, "Bureaucrats take the heat that ought to be aimed at Congress."