Secretary of Interior James G. Watt said yesterday he had told House Interior Committee Chairman Morris K. Udall (D-Ariz.) that unless Udall took steps to control hostile questioning in his committee, "I can't do anything" to advance a giant Arizona water project.

Watt said that since he voiced this warning in a closed-door meeting with Arizona Gov. Bruce Babbitt (D) and the Arizona congressional delegation last month, Udall has "bent over backward" to be accommodating.

Udall said he regarded Watt's comments at the session as "semi-joking," and added, "I don't really think he believes he can threaten me with my own constituency and make me back off on things I believe in . . . .But if he wants war over the Tucson aqueduct, let's have it."

The aqueduct is the final leg on the $2 billion Central Arizona Project, a vast Interior Department project to transport Colorado river water to booming Phoenix and Tucson. Udall is the representative from Tucson.

The meeting Watt held with the Arizona delegation July 21 came five days after the interior secretary had been through a bruising four-hour hearing before Udall's committee in which Democrats had questioned not just his policies but the influence of his fundamentalist religion on his decisions.

Udall refused a Republican demand to cut off the most persistent of the religious questioners, Rep. James H. Weaver (D-Ore.), but called Watt afterward to apologize for what he termed Weaver's "very poor taste."

Watt said in an interview yesterday that when he met with the Arizonans, "I told them that I came to Washington with my batteries charged, but that some days, after what I went through, I really didn't have the energy to do my job. Then I turned to him and said, 'Mo Udall, you drain my batteries, and I can't get my personal energies rebuilt to think about things like the Tucson aqueduct.' "

At that point, according to Watt, Sen. Dennis DeConcini (D-Ariz.) asked, "What can we do?"

"And I said," Watt continued, " 'Senator, I knew someone would ask that question and I've thought about my answer. I'm not asking you to do anything, because anything I mentioned would be blackmail. It is just that until I get my personal energies rebuilt, I can't do anything about the Tucson aqueduct, and I don't know how long that will take.' "

Watt volunteered the description of the meeting in telling a reporter why he thought that despite the drumfire of criticism he has encountered from liberals and environmentalists in Congress, "I can get most of the things done I need to get done."

He said he felt free to talk about the session because an account of it -- from other sources, Watt said -- had been written by Ben Cole of the (Phoenix) Arizona Republic.

Describing Udall's action since then as "very supportive," Watt said he had been invited just this week to join Udall at a Tucson chamber of commerce luncheon -- an action the congressman confirmed.

Asked if he thought he now had Udall under control, Watt responded, "That's right, and he knows it. I know I'll still have some hostile hearings, but he will treat me differently from now on. He knows he needs to control his committee and not allow the religious attacks he has in the past . . . .

"The congressmen know they can get TV coverage just by abusing Jim Watt, but I think from now on, we'll have more substantive, focused hearings -- not these media events."

Informed of Watt's comments, Udall said it was the second time that the Interior secretary had suggested "semi-seriously" that the aqueduct -- whose cost he put at $200 million -- might be hostage to Udall's behavior. Last June 26, the Arizona Republic quoted Watt as saying that "if we don't get the tax and budget cuts, I don't know if we'll have the money for the Tucson aqueduct."

Watt said yesterday that he never believed "anyone as liberal as Udall" could be persuaded to vote for the Reagan administration economic package -- which Udall, in fact, opposed.

But Udall said yesterday, "I have been tempted a couple times to march out in high indignation about his trying to punish the people of Tucson for having me as their congressman. I haven't done it, because I can't believe he would hold my aqueduct hostage.

"It's like two scorpions in a bottle. He's got some decisions he ought to make on Tucson. I've got all of his legislative program coming through my committee. I've never played it that way, but if he wants war over the Tucson aqueduct, let's have it."

Watt said he had no hostility to the project, but noted that he had discretionary authority to settle water allocation questions and construction plans for the Orme Dam and the canal that must precede the preliminary engineering work on the Tucson leg of the project.

Udall recalled that when former president Carter had tried to kill the Central Arizona Project in 1977, "everyone in the delegation turned to me and said, 'He's your guy. You straighten him out.' I think the aqueduct will be built because Barry Goldwater and John Rhodes will, if necessary, go to Reagan and see it's built."

"If Watt is foolish enough to think he can blackmail me -- and I don't think he is -- the people of Tucson would rise up in righteous wrath. For my selfish political purposes, I hope he does it."

But Watt had a different view. "Mo Udall is an interesting guy," he said, "and I really like him. He wears several hats and he speaks accordingly. He's the representative from Tucson and the chairman of my committee and a spokesman for the environmental extremists and one of the liberal spokesmen in Congress. If you can figure out what hat he's wearing, you have no trouble dealing with him.

"He understands I'm not against the Tucson aqueduct. And he understands I'm pretty much in control of the decision on when and how it gets built.

"There are parts of this job," Watt said, "I enjoy."