TUCSON, Ariz. (CN) – A federal judge blocked a controversial plan for a copper mine south of Tucson, Arizona, halting a decade-long process for a Canadian company that hopes to extract copper from a valuable deposit in the Santa Rita Mountains.

The U.S. Forest Service gave its final approval in March for the Rosemont Mine despite numerous lawsuits pending from environmental groups and Native American tribes that oppose it. The approval capped a decade of work costing Rosemont Mining’s Canadian parent company, Hudbay Minerals, roughly $700 million so far, according to their attorneys.

The Forest Service misapplied regulations underpinning its decision and miscalculated the extent to which it can regulate use of land where the mine’s waste rock would sit, U.S. District Judge James A. Soto said in a 37-page ruling Wednesday.

“These defects … led to an inherently flawed analysis from the inception of the proposed Rosemont Mine,” Soto wrote in vacating the Forest Service environmental impact statement and its final approval of the mine plan.

The ruling comes in a 2017 lawsuit filed by Save the Scenic Santa Ritas – a nonprofit founded to fight the mine – and the Center for Biological Diversity, the Arizona Mining Reform Coalition and the Sierra Club’s Grand Canyon Chapter. That lawsuit was later combined with a lawsuit from the Hopi Tribe and the Navajo and Tohono O’odham nations.

“We are heartened that the federal judge recognized that the Forest Service fell short in their duty to protect public lands and resources,” said Gayle Hartmann, president of Save the Scenic Santa Ritas. “Our public lands are a public trust, and we must not allow them to be illegally used to enrich a foreign mining company.”

The Center for Biological Diversity, which has filed several lawsuits challenging the mine on multiple legal fronts, hailed the ruling in a statement.

“This is a crucial victory for jaguars and other wildlife that call the Santa Ritas home,” said Randy Serraglio, conservation advocate at the center. “The judge’s ruling protects important springs and streams from being destroyed. We’ll move forward with everything we’ve got to keep protecting this southern Arizona jewel from this toxic mine.”

Rosemont proposed putting waste rock on mining claims it owns near the pit. The plaintiffs argued July 23 that neither the 1872 Mining Law nor the 1960 Multiple Use Act, both of which govern mining land use, allows Rosemont to dump waste on land outside the claim where the pit will be, in this case about 1,000 acres.

Rosemont claims it can legally pile the rock on an unpatented neighboring claim, but Soto called that claim invalid because the area does not contain any valuable mineral deposits – a requirement for the claim to be valid and a legal spot for the tailings piles, which will dominate the landscape near the mine.

“The fact that Rosemont proposed to dump 1.9 billion tons of waste on its unpatented claims on 2,447 acres of the Coronado National Forest was a potent indication that Rosemont’s unpatented claims on the land in question were invalid,” Soto wrote.

If the company had a valid claim for planned tailings area, it would not bury it under waste, he surmised in the ruling.

The government and Rosemont had also argued that the Multiple Use Act allows the tailings, because it’s an associated aspect of the mining operation. But the environmental groups and tribes argued that that associated activity must be on the mining claim itself.

“Nothing within the Multiple Use Act grants an implied right to use the surface outside of a claim,” Soto wrote.

Soto vacated and remanded the Forest Service decision, permanently halting the work, and also denied a pending request from the plaintiffs for a preliminary injunction.