WASHINGTON — The Bush administration today will unveil a proposal to sell as much as 200,000 acres of national forest land in “isolated parcels” ranging from a quarter of an acre to 200 acres, much of it in California.

The sale is part of a National Forest Service plan to raise $800 million in the next five years to pay for rural schools in 41 states, offsetting shrinking revenues from the sale of timber from national forests. The Bureau of Land Management also plans to sell federal lands to raise an estimated $182 million over five years.

Congress would have to approve the land sales, but it has rejected similar recent proposals.

Environmentalists contend the short-term gain would be more than offset by the loss of public land.

“I am outraged, and I don’t think the public is going to stand for it for one minute,” said Wilderness Society policy analyst Mike Anderson. “It’s a scheme to raise money at the expense of the national forests, the wildlife, recreation and all the other values that Americans hold dear. It’s the ultimate threat to the national forest.”

But Jerry Taylor of the Cato Institute, a libertarian think tank, said the proposed land sales make sense.

“Private property will end up in the possession of those who value it the most,” Taylor said. “That is an iron law of economics.”

Details about what plots of land would be put up for sale are expected to be disclosed at a noon news conference by Undersecretary of Agriculture Mark Rey, a former timber industry lobbyist.

The Forest Service owns 193 million acres of land and plans to sell about 175,000 to 200,000 acres, according to Forest Service spokeswoman Heidi Valetkevitch.

“They could be theoretically from every national forest,” Valetkevitch said. “California has a lot on the list, I understand.”

The lands in question aren’t environmentally sensitive wilderness or protected scenic areas, Valetkevitch said. “It could be something that’s in a neighborhood that people don’t even know is forest land,” she said.

Rural schools get 25 percent of federal forest timber sale proceeds, but those revenues have fallen, so the idea is to sell forest land to make up for that, Valetkevitch said.

Anderson of the Wilderness Society argued that money for rural schools could come from many sources and that the land sales are proposed “so the budget deficit doesn’t get worse.”

And he noted that if forests are sold, future federal timber sales likely would yield even less money for rural schools.