SUPERIOR, Ariz. (AP) — Growing up in a mining family that goes back generations, Mayor Mila Besich knew the Oak Flat Campground as the place where she attended union picnics as a girl and in earlier years her parents stood in a clearing to hear the World Series on the radio.

Now, Besich is overseeing Superior’s fight to build a new copper project at Oak Flat amid worries about the town’s economic future.

Today, the national forest land in the heart of Arizona’s “Copper Corridor” is scattered with 20 rustic campsites among ancient oaks and a hand-painted sign that reads: “Protect Oak Flat, Holy Land.” Buried deep underground is the world’s third-largest deposit of copper ore, big enough to yield 40 billion pounds (18 billion kilograms) of the metal over 60 years.

Competing interests have ignited a tug of war between the town of about 3,000 people who want a huge copper mine built there for its economic benefits, and Native American groups that consider the land sacred and are fighting to protect it from disturbance.

“Our town is going to be the most affected,” said the mayor. “What about our culture?”

Resolution Copper Mining, a joint subsidiary of U.K. and Australian mining giants Rio Tinto and BHP, hopes to build one of the world’s largest underground copper mines at the site outside Superior, about 70 miles (113 kilometers) east of Phoenix. Managing partner Rio Tinto says the mine could satisfy a quarter of growing U.S. demand for copper used in electric vehicles and smartphones.

Resolution began the permitting process nearly a decade ago, but the project has been delayed amid legal and  political wrangling between U.S. agencies and the nonprofit Apache Stronghold, which challenges a planned land swap that would make the project possible. The full U.S. 9th District Court of Appeals is considering Apache Stronghold’s request to permanently halt the project, but the only thing stopping it now is the lack of a new environmental impact statement.

Two other lawsuits challenging the initial environmental review, one filed by the San Carlos Apache Tribe and the other by environmental groups, have gone nowhere since the U.S. government pulled the impact statement for more consultations.

Oak Flat is on Tonto National Forest property to be conveyed to Resolution under a land exchange that Congress approved in a 2014 rider to a must-pass defense bill.

The congressional vote sparked outrage among some Apaches over the site, which features ancient Emory oaks and their acorns and other plants they consider important to their culture and religion. Called Chi’chil Bildagoteel, the site is about an hour’s drive from the San Carlos Apache Reservation and has been used for girls’ coming-of-age celebrations.

Rio Tinto has said it would keep the campground open during the mine’s first decades of operation. But Oak Flat could eventually collapse into a 1.8-mile (2.8-kilometer) crater when massive amounts of rock are removed from below.

Wendsler Nosie, a former San Carlos Apache tribal chairman and longtime activist, is the face of the Save Oak Flat campaign. He earlier fought unsuccessfully to stop a major telescope project on a site in southeastern Arizona that Apaches consider sacred: Mount Graham, or Dzil Nchaa Sí’an.

Nosie said he believes many townspeople quietly back his fight, but “they cannot openly show their support for me.”

When he was recently confronted in an area restaurant by a mining company employee who accused him of endangering jobs, development and good schools, “I stood up and talked about how I’m fighting for land, the water, the earth, religion and our children,” he said, prompting a group of diners to applaud and pay for his dinner.

While the San Carlos Apache leadership opposes the mine, some tribe members support it for the jobs it could generate amid high unemployment on the reservation.

“Oak Flat is not sacred,” said Karen Kitcheyan-Jones, 64, a member who lives on the reservation. “There are many places on the reservation where we can gather acorns and have ceremonies.”

Brenda Astor, Resolution’s principal adviser for Native affairs and a San Carlos Apache member, noted that dozens of other enrolled members also work for the mining company.