The Reagan administration , anxious to cut government spending and sympathetic to needs of private developers, has halted efforts to create a key California park, even though a third of the money to buy the land has been spent.

Supporters of a national recreational area for the Santa Monica Mountains, a line of chapparal hills bordering Los Angeles, say the government's action opens the way for houses that will ruin the "view shed" (bureaucratese for nice scenery) and destroy rara plant and animal life. Opponents contend that a little development will help to ease housing shortages in the city and eventually raise money for better parks. e

It is a case study of two different conservation philosophies in collision -- two different views of what is likely to happen if the $20.4 million in park acquisition funds frozen by Interior Secretary James G. Watt is not spent. The Santa Monicas are one of the closest potential parklands to any major American city, and the debate goes to the heart of what a national park should be and how it should be financed.

The closer the parks are to people, the greater passions they inspire. Much of the Santa Monicas are within a short drive, as little as five miles, from the tract homes of the San Fernando Valley and the fasionable neighborhoods of West Los Angeles.

Despite the mountains' proximity to already developed areas and their somewhat barren apprearance, many conservationists argue that the chain should be left untouched for the enjoyment of visitors and current residents.

"We have to shake the traditional feeling that parks have to high mountains and evergreens far away," said Lou Levy, a Los Angeles pharmacologist and Sierra Club member who is deeply involved in the fight to restore the park funds.

On the other side of the debate, developers and some residents near the mountains argue that new housing will allow more people to enjoy the area, and will provide the government with more funds to improve the parklands it already has.

"If we don't do something about our housing crisis in the cities, certain segments of the population will turn to anarchy and rioting," said developer Alan Satterlee, who is trying to build houses in a Santa Monica canyon that the National Park Service wanted to purchase with the now-frozen funds.

The Santa Monicas are covered by dry grasses and scrubs, forcing existing state parks to close two or three weeks a year because of fire hazard. Trees, plants and animals of great variety thrive in the sheltered little canyons. In his book, "Day Walk in the Santa Monica Mountains," sold to finance Sierra Club efforts to stop development, Levy rhapsodizes over the squirrels, mule deer, bobcats, turkey vultures and even a few mountain lions that inhibits the place. A few ferns, such as the Wodwaria, apparently grow few other places on earth.

Parkland already makes up about 20 percent of the 150,000 acres of the Santa Monicas. Other public agencies hold about 15 percent and 65 percent is in private hands, half of which the park service would like to buy. That is fine with most of the mountains' current population, said Satterlee. Current residents live in $100,00 condominimums or in houses worth $150,000 to $1 million.

"It's the drawbridge approach: 'I'm here, and I don't want you.'" Satterlee said.

The Sierra Club and the park service point out that Satterlee plans to build on what they consider key land. The tract was made famous in the mid-1970s, when its owner, actor Marlon Brando, donated it to an American Indian organization.

"The Indians sold it to me," said Satterlee, declining to say for how much.

He wants to build a 40-acre development in Liberty Canyon to be called "Liberty Estates," with custom-made homes on one-acre tracts costing more than $200,000 each. He views further development as a way to free housing down in the flatlands, and his insistence on big lots and high quality would, he said, mean little adverse impact on the area.

"I live in the Santa Monicas," Satterlee said. "I love and respect them. I'm not bulldozing them."

He evidently is the only developer ready to take advantage of what Santa Monica Mountains National Recreation Area Superintendent Robert Chandler calls the current "holding pattern" that was created when Watt directed that $20.4 million still unspent from a $30 million appropriated park acquisition fund for the mountains be frozen.

The administration has said it plans to request no money at all for acquiring land in the area in the next fiscal year. Congressinal committees now are studying the needs for more funds and local representatives, such as Rep. Anthony C.Beilenson (D-Calif.) and Barry M. Goldwater Jr., (R-Calif.), are said to hope some additional funds -- perhaps $5 million to $10 million -- can be provided.

Beilenson held a big April 4 picnic at one recently acquired park, the old Paramount Ranch movie location site, to encourage support for more park funds. His district encompasses the eastern part of the mountains and he has needled Goldwater, who represents the western half, about Goldwater's support for President Reagan's park budget cuts.

Goldwater is planning to run for the U.S. Senate in 1982. Mindful of the environmental concerns of his constituents and statewide voters, he has sought a compromise. His 11-point program calls for limited development in some federally held areas to raise funds for park development, and exchanges of unneeded federal lands with developers who hold good potential park property.