The Interior Department has big changes in the works: a renewed effort to raise fees in national parks; plans to allow development on thousands of acres of potential wilderness areas in the Southwest; a proposal to reorganize the National Park Service, possibly closing some of its regional offices, and announcements of public lands to be sold in the West.

But not one of them will be unveiled until after Election Day next week, and that is not an accident.

Complexity may be one reason for the delay. But these initiatives are also thought likely to generate intense public opposition, comparable to the furor about Interior Secretary James G. Watt's first pronouncements on wilderness development, several officials said.

Watt, as he himself has acknowledged, is something of a lightning rod for opposition to the administration. According to the officials, Watt and his top aides are convinced that anything he does before Election Day will automatically be converted into anti-GOP fodder.

Next to unemployment and Reaganomics, the combative Interior secretary has emerged as the prime target of Democratic candidates from coast to coast, thanks largely to polls showing deep dislike of his policies and inflammatory style.

To take care of the problem, these officials said, Interior has simply turned off the fodder machine.

Initiatives stalled in the pre-election logjam, but expected to shake loose after Election Day, include:

* Regulations that would reduce public participation in land-use planning on the 300 million acres of western lands run by Interior's Bureau of Land Management -- part of an overall "streamlining" of the process.

* A decision on a draft coal mining rule that the park service contends would open several national parks to strip mining.

* A proposal to change the status of thousands of acres of land being considered for wilderness protection.

Officials said these matters were believed potentially harmful to Republican candidates if announced before the election. Take, for example, a plan to open several thousand acres of potential wilderness areas to development in New Mexico and Arizona.

The announcement of this change, prompted by a recent ruling by Interior's Board of Land Appeals, was expected to go into the Federal Register in June, according to two officials, but was put partly on hold for fear it would hurt the campaigns of two New Mexico Republicans, Sen. Harrison H. Schmitt and Rep. Manuel Lujan Jr.

Both face serious challenges from Democrats attacking what they call the administration's "anti-environmental" policies.

"Watt energizes Republicans, but he also energizes Democrats in the other direction, and he alienates independents. That's just a fact," said one of his aides, who granted an interview on the promise of remaining anonymous.

In the campaign season's last month, Democratic fusillades directed at Watt have appeared to come from every direction.

In Birmingham, Ala., a Democratic congressional challenger is thundering against him. In Portland, Ore., Rep. Les AuCoin (D) has bought valuable television time to denounce his policies.

In whistlestops across the country, Democratic presidential hopeful Walter F. Mondale pillories Watt as the "worst investment we've made in the American environment."

The backlash has renewed speculation that Watt may be replaced after Election Day, but administration sources said President Reagan appears less disturbed than many Republican officials about the "Watt factor."

"If anything, the president feels Jim Watt has taken a lot of heat off the White House by absorbing so many attacks," one administration official said. "You don't like to ask somebody to fall on his sword, but he Watt has been willing to time and time again."

Watt's press spokesman, Doug Baldwin, a longtime friend of the secretary, said Watt plans to be in his job "for about six more years and two months," meaning until the end of Reagan's first term and through another.

Baldwin said Interior had not derailed any programs or announcements because of the elections. Officials who attribute delays to politics are misinformed, Baldwin said.

"There were people in this department who thought Watt would be gone three months ago and they were misinformed, too," he said. "Why should we delay things? No matter what we do here, we're going to get criticized by the people who have a partisan, professional interest in stirring up trouble."

Interior is not the only agency expected to make politically sensitive announcements after the election. The Agriculture Department, for example, plans to ask the next Congress for legislation authorizing sale of millions of acres of national forests it is now legally bound to retain.

Secretary John R. Block announced these plans in August but came under fire from Sen. James A. McClure (R-Idaho), who called it "idiotic" to talk of seeking such broad legislation before the department determined which forests would be sold.

McClure, who chairs the Senate Energy and Natural Resources Committee, has rapped the Interior and Agriculture departments for not making public which lands they plan to sell as part of the administration's controversial program to help reduce the national debt by selling unneeded federal property.

While Watt has repeatedly promised that there will be no "massive" sales of public land, his recent statement that as much as 5 percent of federal lands -- or 35 million acres -- could eventually be sold has fueled a political uproar in the West. There, availability of vast stretches of public land for grazing, mining, hunting and fishing is central to the economy and the way of life.

Interior has yet to identify which lands will be put up for sale, and the suspense alone has become popular Democratic ammunition in western states.

Salt Lake City Mayor Ted Wilson, a Democrat mounting an uphill challenge against Republican Sen. Orrin G. Hatch, has charged in television ads that the administration plans to "sell Utah" to balance the budget.

Idaho Gov. John V. Evans, a Democrat seeking reelection, has warned hunters and fishermen that they could lose valuable recreational lands under the program.

"If the Interior Department would just release which lands are actually on their inventory and likely to be sold, I think it would calm the whole situation," a McClure aide said. "It's not going to be anything like what Democrats are leading people to believe. But it's very, very hot."

Several Interior officials said those lands will not be identified until well after the election.

Interior's spokesmen attribute that and other delays to the complexity of issues. For example, the new land-use planning regulations are being revised because of debate within the department about several key provisions, a spokesman said.

Interior's workload is expected to grow after the elections. Several officials said they have been told not to take vacations between Election Day and Christmas, particularly in the solicitor's office, which scrutinizes regulatory changes.

"There's a joke going around that we'd better bring in our cots after Nov. 2, we're going to be working so hard," said an official who asked not to be named.