Environmental Protection Agency Administrator William D. Ruckelshaus, in a tacit agreement with some of the agency's sharpest critics, said yesterday that the White House is the key to the EPA's success.

"If the agency is going to be successful, there needs to be clear support from the president, clear support from the White House on what it is we're trying to do," Ruckelshaus said in the first interview he has granted since President Reagan picked him for the job on March 21.

But Ruckelshaus singled out Reagan's political party, not the president's environmental policies, as the reason.

"The tendency for people to think of this agency as being at odds with the White House in a Republican administration is very high," he said. "This is true whether it's Nixon, Ford or Ronald Reagan. The primary reason, I think, is because the people, the press and others don't believe Republicans are very good at regulating business."

As a result, he said, there is "a tendency to think that every time the EPA gets aggressive about regulating, it must be doing so at odds with White House desire or policy . . . . You start developing this bunker mentality over here.

"I can't believe how much time it occupies for somebody sitting in this office, trying to keep this agency from believing that, trying to keep the relations between here and the White House on some reasonable basis," he said. "But spending the time at the outset will save me a lot of grief later on."

The amount of time it takes to polish the communication lines between the White House and his waterfront EPA office is just one of the things Ruckelshaus is rediscovering after an eight-year hiatus from public life.

He is finding that some things haven't changed since he left the agency in 1973, after more than two years of service as its first administrator.

The large watercolors of birds that decorate his office wall, for instance, are the same ones his wife, Jill, selected when he moved into the office in 1970.

"They're a little faded," he said, peering intently at the off-pink matboard.

The issues, however, haven't faded.

"I could close my eyes and float back 12 years, and hear the same arguments," Ruckelshaus said, recalling a meeting with state environmental officials this week on federal grants for pollution control.

"More authority, more responsibility, less oversight and more money," he said. "That argument can go on forever."

One of his first initiatives as EPA administrator has been to launch a review of state and federal roles in enforcing environmental laws, in hopes of laying the arguments to rest and ridding the EPA, the states and Congress of a perennial headache that begins to throb each time the question of state pollution grants pops up in the budget process.

But the Environmental Protection Agency has dozens of headaches and that, too, is something Ruckelshaus is rediscovering.

"One of the things that strikes me in coming back here again is how hard these decisions are, particularly the ones that get up here, and how difficult it is to decide how should you strike this balance," he said. "I mean, if you're really trying your best, if you're some Solomon sitting here saying, 'How should I decide this question?'

"It's very hard, and it gets 10 times as hard if the public believes there's something going on there that oughtn't be going on, that some nefarious forces are at work here," he said.

The comment was one of the Ruckelshaus' few references to the controversy that led to the departure of his predecessor, Anne M. Burford, who resigned on March 9 amid a half-dozen congressional inquiries into allegations of political manipulation of agency funds and "sweetheart" deals for industry.

"I don't believe this country can make it if agencies like this go spinning out of control," he said. "And I think it was on the verge of spinning out of control."

He also said he believes that the episode had left an "unfortunate" public impression of the agency, one that he intends to confront with large doses of public access to the EPA's decision-making process.

"It is a very bad mistake in trying to administer an agency like this in not sharing with the public the scientific evidence that the agency has to weigh," he said.

But he again defended, as he did in his confirmation hearings and in numerous earlier letters to administration officials, the agency's right to weigh the costs of its regulations against their expected benefits.

"Somebody has to do it," he said. "We make these judgments all the time in our society . . . . Just because these risk-benefit analyses are subject to abuse--and they are--and they can be overused, does not mean you don't use them.

"Because it's difficult to do so does not mean it's not a valuable way of thinking about how society ought to evaluate risk."

Questioned about national polls that indicate that Americans are willing to pay the extra costs associated with stringent environmental protection, Ruckelshaus dismissed the surveys as an inaccurate gauge of public sentiment on the issue.

"I don't think the public understands cost-benefit analysis in the public health area," he said.

" . . . If you ask the public if we need more regulations to protect public health and the environment, overwhelmingly they'll say 'yes.' Should we protect health and the environment regardless of cost? They'll say 'yes.' "

But he said that the polls do indicate a strong consensus in favor of the goals of environmental laws, if not necessarily the means for achieving them.

"I think what the public was saying to the extent they were saying anything about social regulations was, 'We'll give you some leeway on the means . . . . If you're trying to sacrifice the ends, forget it, brother. We're not for you at all,' " he said.

Many of the EPA's critics contend, however, that policy decisions and budget cuts at the agency over the past two years have compromised the goals of environmental laws.

With the broad bipartisan support of Congress, they have called for a massive infusion of money into the agency, particularly in its enforcement and research divisions.

Ruckelshaus declined to endorse that campaign yesterday, but he denied reports circulating in the agency and on Capitol Hill that he has decided not to seek an amended budget request for fiscal 1984.

"I haven't decided it at all, nor has the administration decided," he said. " . . . I suspect that the agency does need more money. But I'm not sure yet what is realistic in terms of the ability to absorb new money."

Ruckelshaus conceded that senior agency officials had appealed for additional resources for their divisions, but said the move was expected.

"If you are not an advocate for your own program, who will be?" he said.

As for his own program, the phrase that that most frequently rises in Ruckelshaus' conversation is "restore trust."

He said that, more than anything, is the challenge he came back to meet.