In one of his final conservation acts before leaving the White House next week, President Obama on Thursday granted national monument status to Coast Dairies, a 5,785-acre scenic coastal expanse between Santa Cruz and Davenport that stretches for six miles along Highway 1 and features rolling hills, redwood forests and breathtaking ocean views.

Obama added Coast Dairies and five other pieces of land to the existing California Coastal National Monument, an area set up 17 years ago by President Bill Clinton to protect offshore rocks and islands.

The properties, all owned by the U.S. Bureau of Land Management, total roughly 6,230 acres. They include rugged oceanfront bluffs along Humboldt County’s Lost Coast; Trinidad Head, a promontory in Trinidad Harbor near the Oregon border; and the historic Piedras Blancas lighthouse in San Luis Obispo County near Hearst Castle.

The Coast Dairies property was already protected, but the designation could raise the profile of the land and lead to new funding to open the property to the public, supporters said. Also, in some instances, Congress has elevated national monuments into national parks.

“We are grateful to President Obama for this national monument designation,” said Fred Keeley, a former Santa Cruz assemblyman and a board member of the Sempervirens Fund, a non-profit environmental group in Los Altos that led efforts for the designation of the Coast Dairies property.

“It is essential to the continued protection of California’s precious coastline, and the redwood forests and marine terraces that are connected to the coast.”

Presidents can establish national monuments on federally owned land where logging, mining and other activities are banned without a vote of Congress, using their authority under the 1906 Antiquities Act.

Nearly every president has used the law since it was first signed by President Theodore Roosevelt to establish new national monuments, and many eventually were upgraded by Congress to become national parks. Roosevelt used it to set aside the Grand Canyon, Herbert Hoover used it to protect Arches in Utah and Death Valley in California, and President George W. Bush used it to set aside vast areas of the remote Pacific Ocean, including the world’s deepest location, the Marianas Trench.

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Obama also used his authority under the law Thursday to designate three new national monuments to commemorate important sites in America’s civil rights history. They are the Birmingham Civil Rights National Monument in Birmingham, Alabama, the Freedom Riders National Monument in Anniston, Alabama, and the Reconstruction Era National Monument in Beaufort County, South Carolina.

And he used the same authority to expand by 48,000 acres the Cascade-Siskiyou National Monument in southwestern Oregon on Thursday as well.

Most of the California properties are not controversial. But critics who live near the Santa Cruz property, which is officially now called the Cotoni-Coast Dairies National Monument, in part after the Ohlone Indians whose territory once included the area, urged a delay. The property won’t be open to broad public access for years, and opponents fear the designation will attract thousands of people with no place to park, no restrooms and other problems, particularly since monument designation doesn’t guarantee any new federal funding or rangers.

“Once something becomes a national monument it gets worldwide publicity,” said Ted Benhari, a resident of the Bonny Doon area near the new monument. “They haven’t got the funds and personnel to manage it properly. We feel there will be a lot of damage to the flora and fauna. We hope they proceed cautiously.”

Supporters, however, who include environmental groups, Sen. Dianne Feinstein and former Sen. Barbara Boxer, and Rep. Anna Eshoo, D-Palo Alto, said the new designation is likely to help draw in private and federal funds to pay for trails, rangers and other features that will allow it to be opened to the public sooner.

“Monument designation gives it a special status. We think it is so worthy. The land is absolutely extraordinary,” said Will Rogers, president of the Trust for Public Land, a San Francisco environmental group.

The property was already protected from development, before Obama’s action Thursday. For most of the 20th century, it was run as a farm and ranching operation by the descendants of two Swiss families. By the 1970s, developers regularly proposed golf courses, hotels and subdivisions on it.

After purchase by Save the Redwoods League in 1998 with roughly $40 million from the David and Lucile Packard Foundation, it was transferred to the Trust for Public Land. Then, in 2006, the trust donated about 400 acres of its beaches to the state parks department, and in 2014, transferred most of the rest of the land to the Bureau of Land Management with permanent deed restrictions banning mining, fracking, recreational motorcycle riding and other uses.

Some environmentalists have worried that incoming President Donald Trump might try to undo Obama’s monument designations. No president has ever revoked a monument. The 1906 law used does not contain language about how to revoke monuments, and a court fight with environmental groups would be certain if Trump tried, Rogers said.

Last year, the BLM began docent-led hiking tours and is now patrolling the land. But it has not yet set a date for broad public access because of the limited number of rangers and funds. Although BLM has owned the property for two years, there are no signs, parking areas or restrooms, or a management plan for the land.

President Obama on Thursday added six federally owned properties to the California Coast National Monument, raising their stature, and environmentalists, hope, their levels of protection. They are:

Coast Dairies — a 5,785-acre former dairy ranch that stretches for six miles along Highway 1 near Davenport in Santa Cruz County.

Trinidad Head — 13 acres of rocky shoreline in Humboldt County, which is home to the Trinidad Head lighthouse, built in 1871.

The Lost Coast Headlands — 440 acres in Humboldt County just south of the mouth of the Eel River, with rugged forests and beaches.

Lighthouse Ranch — 8 acres located 11 miles south of Eureka, with panoramic views of the Eel River Delta, Humboldt Bay and the Pacific Ocean.

Piedras Blancas — 20 acres in northern San Luis Obispo that is well-known for its 1874 lighthouse and nearby colony of elephant seals.

Orange County offshore — A group of small rocks and islands off the coast of Orange County that in the 1930s were considered by the Coast Guard for lighthouses.