Wolf Trap Farm Park has received about half-a-million dollars in donations toward the estimated $17.5 million needed to rebuild the Filene Center, Wolf Trap's founder, Catherine Filene Shouse, said this week. The center was destroyed by fire on April 4.

"We don't have very much in hand," Shouse said during an interview. "We have a lot of good will."

Further fund raising, she said, hinges on the report from the task force set up by President Reagan on April 5 to examine the future of Wolf Trap. The park is maintained by the National Park Service.

"There are those who are certain that the government will offer 50-50," said Shouse. "Some feel it should be 80-20," she said, meaning 80 percent from the government and 20 percent from the private sector. She said she shares the latter feeling.

But Frank Hodsoll, chairman of the National Endowment for the Arts and a member of the task force, said he has talked with members of Congress, and "most of the talk on the Hill has been a maximum of 50-50."

Hodsoll said the administration "doesn't have a view on what we would work with Congress to get." Since Congress must approve the figure that the administration recommends, the issue would go first to the House appropriations subcommittee on the interior, chaired by Rep. Sidney Yates (D-Ill.).

"I talked to Mrs. Shouse yesterday," said Yates. "I said--and she agreed--that we ought to see what the president's two people on the task force come up with . . . She asked me, 'Is there something you can do?' I said, 'No, they're making their own report.' "

Part of the reason it has taken so long to produce the report, Hodsoll said, is that they're "trying to get a complete assessment of the damage. For a long time, no one could get into it because the fire marshals had roped it off. A lot will depend on whether the foundations are solid. Everyone agrees the superstructure has to be torn down." National Park Service engineers are optimistic that the concrete foundation of the building can be salvaged.

"The government moves slowly," said Shouse. "That's why the Wolf Trap Foundation is anxious to have the private sector direct the rebuilding." Shouse said that if the government undertook the rebuilding, "it would take 10 to 12 years, and by that time, Wolf Trap would be dead in spirit."

Shouse said the delay is "very understandable," and she is "not disgruntled." "This delay should not be emphasized," she said. "It's not as simple as it looks. A great many people have tried to help figure out what the government should pay . . . Many, many people in government have been very understanding."

But she added, "I'm just disappointed that we haven't gotten answers sooner . . . The public is disappointed. They're waiting to make their donations. We are constantly asked, 'Was it insured?' 'No,' we say. 'Why?' 'The federal government doesn't insure.' 'If it doesn't insure it, shouldn't the federal government build it?' 'Yes, but if we waited for the government to build it, it would be dead.' "

Shouse donated to the federal government the land for the park and $2.3 million to build the theater 11 years ago.

"I've had many disappointments since 1965," she said referring to the year of her first overtures to the government. Her gift, she said, "was accepted in 1966. But there were delays. Even the awarding of the first contract was delayed. I've been disappointed in the care the government has taken of the buildings . . . We've never had sufficient watchmen. Experience shows that more watchmen are needed and so are better alarms."

Shouse admitted to being "an impatient person," and said of the rebuilding, "I don't sleep because I'm worrying about the financing and where it's coming from." Reminders of Wolf Trap pervade her stately F Street town house, one of the last residential survivors in a neighborhood of modern offices and trendy eateries: Fund-raisers come by for breakfast meetings, a volunteer types letters, the uniformed housekeeper who greets visitors sports a "Wolf Trap Lives" button on her blouse.

Wolf Trap, like most property owned by the federal government, is "self-insured," which means uninsured. Instead of paying costly premiums, the government decided it had sufficient financial ability to meet liability claims and, if it chose, to rebuild it.

If the government did contribute 50 percent of the rebuilding costs, Wolf Trap would have to raise more than $8 million. "I think it's an undue burden," said Shouse. "I think we're prepared to raise $3 million or $4 million. David Packard Wolf Trap Foundation board member and chairman of the Hewlett-Packard Corp. has said that 80-20 is the more acceptable figure."

But Shouse added, "If we only get 50 percent now, we might have future support from the federal government."

Despite widespread publicity and an outpouring of good will in the last month, the task of the Wolf Trap fund-raisers is doubly formidable because it comes during a time of economic recession when private funding sources are already besieged with requests from philanthropic organizations hit by federal budget cuts.

Shouse, who hopes to raise more funds from a telethon this month, pointed out that "most of our gifts are small ones."

Yates said he has received calls about Wolf Trap from Rep. Frank Wolf (R-Va.), Sen. James McClure (R-Idaho), chairman of the Senate appropriations subcommittee on the interior, Sen. John Warner (R-Va.) and Nancy Hanks, former chairman of the National Endowment for the Arts.

Wolf gave a one-minute speech on the floor of the House about Wolf Trap and then sent it to key people in the House. He says he has also talked with the Republican leadership--"just trying to educate people to the fact that this was a federal park"--and David Gergen and Michael Deaver at the White House. "I think Congress will be very responsive to doing what has to be done to rebuild," Wolf said. "And most of the congressmen live in the neighborhood."

Shouse said she hoped the temporary structure being shipped from the Middle East would not be in use for more than a year. "That's why we're impatient," she said.

"With all the good will around," she added, "I can't be too depressed. But I'm just impatient to start on full-fledged fund raising."