WASHINGTON — President Barack Obama will designate Chimney Rock as a national monument Friday — a move that will help preserve the 4,726 acres in southwestern Colorado, administration officials told The Denver Post Wednesday.

Chimney Rock is composed of a chunk of the San Juan National Forest and is surrounded by the Southern Ute Indian Reservation.

The land will be managed by the United States Department of Agriculture and the Forest Service and White House officials said they will work with the tribes in the area.

Ranchers who use the area for grazing will maintain those rights as well, administration officials said.

The site is deeply spiritual to the Puebloan people and other tribes. Ancestors used the rock to see “lunar standstills” — a phenomenon that only happens every 18.6 years when the moon rises exactly between the two stone pillars of Chimney Rock.

Both Republicans and Democrats in Congress has been working on this designation for two years, but it had stalled in the U.S. Senate.

“For the last three years we’ve been making that case to Congress and more recently we’ve been urging the administration to use its authority under the Antiquities Act,” said Sen. Michael Bennet, a Democrat.

“Making Chimney Rock a national monument will be an extraordinary boost for the region by preserving and protecting the site and driving tourism, which would draw more visitors and bring more dollars into the local, regional and state economies.”

Rep. Scott Tipton, R-Cortez, who represents the area, sponsored a bill that passed the U.S. House of Representatives in May. Bennet and Sen. Mark Udall, a Democrat, co-sponsored companion legislation in the U.S. Senate, but it never passed.

“I’m a strong believer that this and all public lands designations be locally driven, and as such the preferred method to advance this designation would be through legislation,” Tipton said, in a statement. “That said, I’m ultimately pleased to see a Chimney Rock National Monument becoming a reality.”

Tipton and Bennet sent a letter to Obama in April, urging him to begin a dialogue with the local community to explore all options to give the Chimney Rock archeological site distinction. The same month, the pair also hosted a listening session with community leaders.

This is the third designation Obama has made under the Antiquities Act.