Interior Secretary James G. Watt is waging a one-man media campaign to tell Americans something he says they never have heard about him: the truth.

Facing increasing pressure to resign, Watt recently has blitzed the talk-show circuit, appearing on "Face the Nation," "Meet the Press," "Good Morning America," "The Larry King Show" and "Evans and Novak" to tell millions of viewers that he is, in fact, a conservationist whose record has been maliciously distorted by foes.

Pulling out colorful budget charts, the interior secretary announced that "the commitment to the national parks" has doubled since his arrival ("Meet the Press").

Asked about opposition to his policies, particularly in the West, he responded: "I have the full support of the Congress on all issues" ("Face the Nation,") and "The governors of the West fully support everything we're doing" ("Meet the Press").

Sheafs of talk-show transcripts have created a new problem for him. In his zeal to promote his record, Watt made statements about national parks, his resource development programs and his many critics that do not always match the public record.

President Reagan stumbled recently when he followed up on one of Watt's chart-and-graph presentations by announcing at a news conference that he has in two years spent "more money on parks and acquisition of parks than the previous administration spent in all its four years."

A White House spokesman retracted the statement when questioned by reporters. Watt's steeply inclining chart reflected only part of the parks budget--money for construction and repairs--or about one-sixth of the total.

Watt has doubled that portion of the budget from the last year of the Carter administration when it was sharply reduced, but Carter's four budgets for parks totaled $2.9 billion, according to Interior Department records. Reagan's will reach $1.5 billion at the end of this year.

Watt's statements have prompted an unusual series of attacks on his veracity, swelling the volume of protest against him just as he is campaigning to quell it.

"I used to think that the difference between Joe McCarthy and James Watt was that McCarthy knew he was lying and Watt didn't," former senator Gaylord Nelson (D-Wis.) said. Nelson heads the Wilderness Society, one of the most outspoken of the environmental groups calling for Watt's ouster. "But I no longer think that because his misrepresentations are so blatant and so obvious and so specific that there's no way he could be unaware of the deceit he's perpetrating."

After reviewing the transcript of one Watt truth-telling session, Rep. Sidney R. Yates (D-Ill.), chairman of the House Appropriations subcommittee that handles Watt's budget, took issue on the House floor with the secretary's claims by quoting from federal budget documents and concluding: "Any resemblance of Mr. Watt's testimony to the truth on that day is purely coincidental."

Several Republican congressmen have complained privately about Watt's statements and, according to one congressional aide, "we're going to take violent issue with him on both sides of the aisle if he says some of that stuff in our committee."

Watt's claim that he enjoys the backing of all western governors spurred Colorado Gov. Richard D. Lamm (D) to send a letter citing several pending battles with the Interior Department. Nine western governors last year supported a resolution criticizing Watt's plans to sell public lands in their states, and Lamm has opposed all proposed regulations for leasing oil shale.

And New Mexico Gov. Toney Anaya (D) remarked: "I've called for his resignation. I'm opposing his coal-leasing program, his wilderness policies, his positions on native Americans. For him to say that is unprofessional, unfair and untrue."

Watt's press secretary and longtime friend, Douglas Baldwin, said Watt stands behind all of his statements, adding that the thunderous attacks on his veracity prove he cannot receive a hearing without being battered.

"We've taken a terrible beating from environmental people. Their whole intellectual contribution to this attempt of ours to disseminate information is to come back with bombast about foxes in henhouses," Baldwin said. "They haven't answered his statements with their own specifics."

Yates and several environmental groups have supplied some specifics of their own, however.

Watt told the House Interior Committee that in each of the four years before his arrival, "Congress cut the budget which was supposed to take care of the national park system. No wonder it was hurting."

Yates inserted into the Congressional Record federal budget statistics showing an increase in total appropriations for construction and operations in the parks for three of the four years before Watt took office--from $426 million in 1977 to $502 million in 1981.

Watt's charts, showing a decline of $173.9 million in 1978 to $79.6 million in 1981, highlighted budgets for heavy maintenance and construction in the parks.

Baldwin countered that Yates' figures "are accurate, but they're only part of the story," the same charge the congressman made against Watt.

In his media sessions, Watt has raised some telling questions. Why, he asked, was the Carter administration subjected to little of the public uproar that surrounds Watt's every move, when in its last year the budget for construction of park facilities such as roads and sewers was halved as a cost-saving measure? He went further, lambasting his predecessors for what he called "shameful" neglect of parks and accused them of fostering a crisis that he must resolve.

"When I came in, I believe we were flushing raw sewage water into the streams and lakes of our national parks," Watt said before the House Interior Committee and on one talk show.

"Raw sewage? The thought is so horrible," Yates said, that he asked Watt's chief park adviser for documentation after reviewing a transcript of the secretary's remarks. The memo that came back from National Park Service Director Russell E. Dickenson cited failures in several aging park sewer systems but no cases of sewage flowing into park streams and lakes.

In two television appearances, Watt has promoted his plan to auction billions of tons of federally owned coal reserves by arguing that environmental laws make it uneconomical to mine most of the coal leased by past administrations. To meet the nation's energy needs, Watt said on "Meet the Press," the auctions are necessary.

But the Office of Technology Assessment, in the most comprehensive study of federal coal leasing, reported in late 1981 that environmental laws would hinder development of only 6 percent of coal leased before Watt's arrival. The coal leased by past administrations will supply the nation's energy needs into the 21st century, the study concluded.

Baldwin termed the study by OTA, the scientific arm of Congress, a "political estimate," adding: "Watt's not speaking off the wall. He knows what he's talking about."

The coal program is under investigation by the House Appropriations Committee and the General Accounting Office, and sources said both soon will criticize the program for turning over too much government coal to industry at low prices.

There is a bipartisan move in Congress to impose a ban on the auctions after this year, amid charges by critics that they amount to a "giveaway," and Anaya has asked the Interior Department to cancel most of its coal-leasing plans in his state.

But Watt, on "Face the Nation," said: "We have the full support of the Congress and all of the governors on coal leasing."

It is well known that Watt has a markedly different view of his calling as interior secretary than did most of his predecessors, one that angers conservationists of both parties. In the world presented in his latest media sessions, Watt sees his predecessors of both parties hobbling the country by restraining development of energy resources on federal lands and in coastal waters.

Watt said he is on a mission to "restore America's greatness," promoting more coal mining, more oil drilling, and in the process, transferring control over vast quantities of natural resources from federal to private interests.

Recently, however, his mission has been threatened. He has been called a liability by leading Republicans in the wake of upheavals at the Environmental Protection Agency, which turned the environment into one of the most explosive domestic issues facing Reagan. Since administrator Anne M. Burford left the EPA under fire last month, the White House has been under growing pressure to remove Watt as a signal of across-the-board changes in environmental policy, several administration officials said.

Watt has counterattacked in his media sessions, arguing that his negative image is a result of unfair press coverage and a "multimillion-dollar campaign of hatred" by environmentalists, whom he has called "a left-wing cult" that seeks to centralize government and "bring down the type of government I believe in."

He told a mostly Republican audience at the Capitol Hill Club's "headliner breakfast" last week that Massachusetts Gov. Michael S. Dukakis (D), whose state recently blocked Watt's offshore leasing plans near Cape Cod through a lawsuit, was controlled by environmental groups.

Watt quoted Dukakis as telling him that the state was forced to file suit to block the offshore drilling program "because he Dukakis had to run the whole package by certain environmental groups, including Greenpeace, and they said it's got to be killed," Baldwin said.

"The man must be hallucinating," Dukakis said when asked about the conversation related by Watt. Dukakis said he and his staff attempted to negotiate a compromise with the Interior Department, but went to court after concluding that the program posed hazards for the environment and the fishing and tourism industry.

Watt's public relations campaign also has included luncheons with select groups of reporters, presentations to congressmen, lengthy interviews with national publications and less well-known journals. His aides said he has no plans to scale it back, despite the fallout.

"I have the ability to just lay it out like it is, and I speak the truth as I see it," Watt has said ("Good Morning America"). "People react in different ways."