Bid to reopen one of California’s most storied gold mines shot down — for now

The Nevada County Board of Supervisors ruled Thursday that the company, Rise Gold, and its local subsidiary failed to prove longtime rights to extract potentially billions in gold from the 150-year-old Idaho-Maryland Mine near Grass Valley.

The decision, though, came as relief for many in the community. Residents in the area, about 60 miles northeast of Sacramento, have widely opposed the return of mining to their quiet foothill community. The industry’s impact on the region still shows from the Gold Rush two centuries ago, in the form of such environmental scars as polluted water and soil.

The Idaho-Maryland Mine, a complex of mines that consists of 73 miles of underground tunnels, opened in the 1860s and operated on and off until the 1950s. During its run, it produced more than $4 billion in gold, by today’s prices. Representatives of Rise Gold believe there’s still a lot more precious metal to be had there.

The company, which has been pulling gold samples from the mine in recent years, petitioned Nevada County to confirm its vested rights this fall. Vested rights generally mean that an activity that occurred in the past, such as mining, can continue as it had despite newer restrictions. Proving the right often entails showing the activity has continued since being regulated.

Representatives of Rise Gold argued that even though mining has not taken place on the property for decades, the intent to mine was always there, which they said preserves the company’s rights to mine.

County staff disagreed, saying the vested rights had been abandoned in the mid-1950s when the mine shut down, the equipment was sold and water filled the tunnels. The property has changed hands multiple times.

The county Board of Supervisors, after two days of public testimony that largely focused on the definition of a vested right, unanimously sided with staff and concluded there were no vested rights to mine.

The decision does not mean the mine is dead. Rise Gold has begun seeking a permit from the county to mine at the site, a process that — unlike vested rights — involves a thorough environmental review and sign-off from county supervisors. The county Planning Commission has recommended the board deny the application.

“Yes, that use permit is going to be very difficult because of what mining represents and its location in the proximity of Grass Valley,” said Board Chair Ed Scofield at the hearing Thursday. But “this does not mean Rise Gold cannot mine.”

Reach Kurtis Alexander: kalexander@sfchronicle.com Twitter: @kurtisalexander