Congressional leaders are seeking to work out compromises on the three bills President Carter has threatened to veto, according to members and their aides.

The measures, which set future price supports for farm commodities and provide fiscal 1978 money for water projects and the departments of Labor and Health, Education and Welfare, are part way through the congressional approval process.

White House aides working on the same measures, however, say they don't consider some new congressional proposals as compromises at all.

"Everybody," as one Capitol Hill figure put it yesterday, "is guessing on what the President will finally agree to."

Today, a Senate Appropriations subcommittee is to meet on the public works money bill and delete funds for four or more water projects that Carter wants halted.

The House Appropriations Committee dropped only one of 18 projects Carter opposed when it approved the $10.2 billion measure.

Sen. John C. Stennis (D-Miss.), chairman of the appropriations subcommittee, "seriously wants an accommodation," a Senate aide said yesterday. He described how aides to the Mississippian had been working to get senators with projects on the Carter "hit list" to cooperate in agreeing to have them halted.

Only one, however, Sen. J. Bennett Johnston (D-La.), reportedly agreed to a project cut - dropping a $2 million Bayou Bodeau levee and channelization project on a Louisiana river that would have benefited only 60 landowners.

Johnston reportedly plans to justify his action to his constitutuents to the grounds that he wanted to avoid a veto.

Two other "hit-list" projects probably will be dropped by the subcommittee because the senators from the states involved have opposed them. One of these, the $88.7 million Meremac Park Lake in Missouri, was the first water project Carter promised to halt during his 1976 campaign for the Democratic presidential nomination.

An Oklahoma "hit list" project, the $29.6 million Luktata Lake, will probably also get deleted because its chief sponsor, former House speaker Carl Albert (D-Okla.), is no longer in Congress to protect it.

Several other projects are also candidates for deletion, according to one subcommittee member.

But while Stennis works to cut a "hit list" project here and there, White House aides are working on the other side of the Capitol for an amendment that would delete the entire 18-project list from the bill when it comes to the House floor next Monday.

Carter, an aide said recently, "made his compromise when he cut the hit list from 2 to 18."

Rep. Phillip Burton (D-Calif.), who lost a close vote in January to be House majority leader, was reported by White House aides as the prospective leader for the Carter amendement.

That would pit Burton against the man who defeated him, House Majority Leader Jim Wright (D-Tex.), who is the chief supporter of the water projects program.

Carter stands to fare much better on the farm bill controversy. Key senators, according to their aides have already agreed to drop high price supports voted in the Senate version of the farm bill when the measure goes to conference with the House.

Carter has said he would accept price supports at levels contained in a House Agriculture Committee-approved measure but would veto the bill if it contained the higher Senate figures.

Like the water projects Jockeying, the Labor-HEW money bill is being handled at two levels.

When the measure comes to the House floor June 15, a Carter-supported amendment is expected to be proposed to delete over $700 million for impact school aid and direct student loan programs.