WASHINGTON — The Trump administration threatened Thursday to undo a hard-fought conservation plan to protect millions of acres of California’s Mojave Desert from industrial development.

The joint state-federal Desert Renewable Energy Conservation Plan aims to protect fragile desert lands in the state while steering renewable energy projects to lands least at risk for environmental damage. But the federal Bureau of Land Management said it is considering re-examining the plan to comply with an executive order by President Trump last year to increase energy development on public lands.

“We need to reduce burdens on all domestic energy development, including solar, wind and other renewables,” said Katharine MacGregor, principal deputy assistant secretary for land and minerals.

The administration’s announcement brought a swift rebuke from Sen. Dianne Feinstein, D-Calif., who has spent her entire Senate career attempting in one form or another to protect the desert, including authoring legislation for the creation and enlargements of Death Valley National Park, Joshua Tree National Park and the Mojave National Preserve.

“Scrapping the plan now is a complete waste of time and money, and I oppose this,” Feinstein said in a statement.

The Desert Renewable Energy Conservation Plan took years to complete under the Obama administration, and was an attempt to correct mistakes made during that administration’s first years in office when the California desert was opened to large-scale solar development without taking into account the broader environmental impacts.

The plan attempts to strike a balance over 22.5 million acres of the California desert between conservation efforts and solar and wind development. The area takes in seven counties: Imperial, Inyo, Kern, Los Angeles, Riverside, San Bernardino and San Diego.

Finalized in the last months of the Obama presidency, it set aside 388,000 acres, or more than 600 square miles, of public land in the Mojave for renewable-energy development and made another 842,000 acres available if needed. In all, nearly 2,000 square miles of desert could be developed currently.

The plan also set aside 5 million acres, or 7,812 square miles, for conservation.

Reopening the plan “is a very bad idea, unproductive and is not really going to help anyone,” said Karen Douglas, a member of the California Energy Commission and the state’s chief official who oversaw the plan’s development.

The action was seen as especially suspect by critics given that the administration has been mostly hostile to renewable energy, seeking to cut federal funding for such projects while easing the way for oil, gas and coal development under Interior Secretary Ryan Zinke.

Last fall, the administration proposed reopening 1 million acres in the area to new mining claims.

If the administration reopens the plan, development might not necessarily be limited to renewable energy, said David Lamfrom, desert director for the National Parks and Conservation Association, an environmental group that was deeply involved in the development of the desert conservation plan.

“The administration could make any determination it wants,” Lamfrom said. “It could open up lands to resource extraction of all types. It could mean all kinds of things that are not necessarily what local communities want and not what the state of California wants.”

Douglas said the desert planning process involved numerous scientific studies and sought advice from numerous interests, ranging from the U.S. military, which has enormous bases in the area, to conservationists, recreational users, Indian tribes and solar developers.

“The record developed for the DRECP is very strong,” Douglas said. “There was a lot of data assembled.”

If the administration wants to make changes to the plan, she said, “not only would they have to have public meetings and take comment, but they’d also have to present facts and new information and point to changed circumstances or some way justify why they believe the facts on the ground merit a different conclusion.”

Douglas also said that with the plan now in effect, the state is well on its way to meeting its new goal of getting half the state’s energy from renewable sources.

Alex Daue, assistant director for energy and climate at the Wilderness Society, called reopening the plan “a cynical attempt by the Trump administration to undermine both renewable energy and conservation,” and another example of Zinke and Trump creating “chaos for our public lands.”

Carolyn Lochhead is The San Francisco Chronicle’s Washington correspondent. Email: clochhead@sfchronicle.com Twitter: @carolynlochhead