Historic California gold mine could reopen, may still hold fortune

In California’s long affair with gold, the 160-year-old Idaho-Maryland Mine stands out as one of the great mother lodes.

Its 73 miles of tunnels, an hour north of where the discovery of gold kicked off the historic rush of forty-niners, bustled with rickety mine cars and workers in hard hats, on and off from the 1860s to 1956.

During its run, the mine unearthed some of the largest underground treasure California has seen. In total, more than $4 billion worth of gold, by today’s prices, was pried from the site, near Grass Valley in Nevada County.

Next week, Nevada County officials are scheduled to decide whether the rights to mine gold at the complex are still valid. The verdict will determine whether a mining company headquartered in Vancouver, Canada can proceed with plans to reopen the storied facility and revive a rich but controversial piece of California’s past. Company representatives believe one of the world’s highest-grade gold reserves remains nestled underground. 

While some wax nostalgic for the region’s Gold Rush, many in the area don’t want to see the now quiet Sierra foothills 60 miles northeast of Sacramento return to their industrial heyday. Plans by Rise Gold Corp. and its local subsidiary call for up to 24-hour, seven-day-a-week drilling and rock processing at the eastern edge of Grass Valley, which today is popular with retirees, Bay Area transplants and tourists.

“They’re talking about putting the mine in the middle of a residential area,” said Ralph Silberstein, a Grass Valley resident and president of the Community Environmental Advocates Foundation, which promotes sustainability in the county and has organized a campaign against the mine. “It has too many impacts.”

Beyond noise, another concern is environmental harm. Even as the commercial pursuit of precious metal has largely ceased in Gold Country, iron and sulfuric acid from mining in previous centuries still pollute creeks, and arsenic from blasting is pervasive in soil. Some also worry that if the mining tunnels are dewatered, the water table could drop and cause nearby wells to go dry.

Representatives of Rise Gold, which began acquiring property and mineral rights in the area in 2017, have been working to assure the community that modern mining is different, and much less destructive, than in the past.

“We aren’t reproducing the same type of operation that existed before,” Joe Mullin, president and CEO of Rise Gold, told the Chronicle.

Drilling would take place hundreds, if not thousands, of feet below the service and be virtually unnoticeable, according to the environmental documents prepared for the county. Most of the noise from above-ground activities would fall within the county’s noise standards, the documents suggest. Also, today’s mining laws are much more restrictive in terms of cleanup.

Mullin said the operation would yield more than 300 full-time jobs, with pay in excess of $140,000, including benefits, and produce more property tax than any other business in the county.

The company’s interest in reopening the Idaho-Maryland Mine was prompted by recent exploration efforts at the site, which revealed lucrative deposits of gold, potentially worth billions, employees say. The fact that tunnels have already been built, they say, gives the company a leg up at getting at the anticipated fortune.

Still, extracting gold from within the earth remains a difficult and expensive endeavor, mining experts say. The handful of gold operations that still exist in California are mostly pit mines, where the valuable metal is plucked out near the surface.

Whether Rise Gold can move forward with its plan to reopen the tunnels hinges on the company’s bid to prove vested mining rights. 

Vested rights are generally exercised to ensure a property owner can continue a certain activity when authorities restrict that activity at a later date. Proving the right often involves showing the activity has continued since it was regulated.

Company officials have petitioned the Nevada County Board of Supervisors to confirm vested rights for the mine, which would allow mining to resume without the rigorous county-approval process.

Rise Gold has asserted that even if mining hasn’t continued since the county required a use permit, the “intent” to mine was never abandoned, which the company says preserves the vested right.

“Not only was there no intent to abandon the right by us or the previous owners, but there were efforts to reactivate the mine,” Mullin said.

County planning officials, however, say the argument falls short.

In a report issued last week, county staff concluded that the vested rights expired as early as 1956, when mining ceased on the property and the equipment was liquidated. The site has since had other owners with different pursuits, such as timber production.

The Nevada County Board of Supervisors, though, reserves final say on the matter, and a public hearing on the vested rights is set for next Wednesday.

Even if the company’s petition is denied, the pursuit of mining is not dead.

Rise Gold is already knee-deep in motions to try to get permitted by the county for new mining activity, a process that was put on hold when the company instead sought to exercise vested rights. The permitting process got less encouraging for Rise Gold, though, when the county’s Planning Commission recommended that the Board of Supervisors not give the go-ahead.

Opponents have vowed to fight the project no matter what route Rise Gold takes to reopen the mine.

“Our organization exists, our job exists today to deal with the damage of the last Gold Rush,” said Aaron Zettler-Mann, executive director of the South Yuba River Citizens League, a community group that seeks to restore and protect the region’s environment. “The idea that we’d start again… it’s hard to get your head around.”

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