Biden Administration Said to Expand Two California National Monuments

President Biden plans to expand the perimeters of two national monuments in California, protecting mountains and meadows in a remote area between Napa and Mendocino as well as a rugged stretch east of Los Angeles, two people familiar with the administration’s plans said Thursday.

The San Gabriel Mountains National Monument and the Berryessa Snow Mountain National Monument will each get new boundaries designed to protect land of cultural significance to Native American tribes, as well as biodiversity and wildlife corridors, said the people, who asked not to be named because they were not authorized to discuss the plans publicly.

The San Gabriel monument encompasses 342,177 acres of the Angeles National Forest and 4,002 acres of neighboring San Bernardino National Forest. Mr. Biden intends to expand the monument by approximately 110,000 acres.

The Berryessa Snow Mountain National Monument includes nearly 331,000 acres of protected land in parts of Napa, Yolo, Solano, Lake, Colusa, Glenn and Mendocino counties, from Pacific Ocean beaches to a 7,000-foot mountain. It would be expanded by about 13,753 acres under Mr. Biden’s plan.

Native American tribes call the expansion area on the eastern edge of the existing Berryessa monument Molok Luyuk, or Condor Ridge.

Both monuments were created by former President Barack Obama under the Antiquities Act, a 1906 law that authorizes the president to protect lands and waters for the benefit of all Americans. California lawmakers and tribal organizations have pressed Mr. Biden to make the declaration as part of the administration’s land conservation plan.

John Podesta, President Biden’s senior adviser on climate change, said Thursday that Mr. Biden has preserved more land than either Mr. Obama or former President Bill Clinton.

“I think we’ve got more to come, including better use and better protection of public lands,” Mr. Podesta said at an event hosted by The Washington Post, which first reported the expected monument designations. The White House declined to comment.

Senator Alex Padilla, Democrat of California, who has introduced legislation to expand both monuments, has called the areas havens for biodiversity and said that the San Gabriel monument is one of the only green spaces accessible to low-income families in the Los Angeles area.

“The Biden administration knows the value of protecting our public lands to combat climate change and ensure our communities have access to the outdoors,” Mr. Padilla said in a statement. “I look forward to working with them to safeguard some of California’s most treasured natural landscapes and ensure they are around for future generations to enjoy.”

Legislation to expand both monuments has been stuck in Congress although there has been little to no opposition. A wind project did threaten to encroach on the Berryessa monument, but the Biden administration denied a permit for the project in 2022.

Supporters of the expansion say the Berryessa monument is biologically diverse and holds special significance for tribes in the area. Expanding its perimeter would protect it from any future development.

“We are really excited to hear about the president’s plans,” said Elaye Stefanick, the California program director for Conservation Lands Foundation, an environmental group. She said she hoped that the federal government would partner with tribes on how to best manage the expanded monument.

Rudy Ortega Jr. is the tribal president of the Fernandeño Tataviam Band of Mission Indians, whose members are native to the region around the San Gabriel monument. He said that tribal members have been nervous about urban development encroaching on monument land, and that the expansion would reduce that threat.

“The tribes like to see that as an open space,” Mr. Ortega said. “We know that the future generations of our ancestral villages will be able to go back and continue to visit.”