An old Calaveras County gold mine stands accused of polluting streams and groundwater with arsenic.

Mine representatives say their property didn't do it.

But if the complaint holds up in front of the California Water Quality Control Board this summer, cleanup costs for the Reno mining company could more than double from $25 million to $55 million.

The Royal Mountain King Gold Mine near Copperopolis operated from 1989 to 1994. It employed about 125 people, most from Calaveras and Tuolumne counties. Meridian Beartrack Company in Reno owns the site.

The pollution problems stem not from the gold mining itself, but from the mine's closure and cleanup, said representatives from the Central Valley Regional Water Quality Control Board. That board oversees water quality in the San Joaquin Valley, Sacramento Valley and western Sierra.

The board's biggest problems with the cleanup relate to a giant pit at the mine that holds 50 to 60 tons of rock that was blasted or cut from the ground during mining operations. While they did not bear gold, the rocks are considered waste because they were taken from their original location in the ground and must now be disposed of somewhere else.

This rock pit is covered with about 6 inches of topsoil, which is blanketed with green grass.

But Regional Water Board officials said the topsoil is not enough to protect groundwater in the Diamond XX subdivision, Flowers Reservoir and Littlejohns Creek from minerals such as cyanide and arsenic.

People in the Diamond XX subdivision have been notified of the arsenic levels in their well water.

No one takes water directly from Flowers Reservoir it flows into the San Joaquin River, and the arsenic levels in both the reservoir and Littlejohns Creek have officials worried for wildlife safety.

After rain permeates the pit's topsoil, it slides through crevices between rocks in the pit before hitting the groundwater supply. Kim Schwab, engineering geologist with the Regional Water Board, said that as the water filters through the rocks, minerals from the stones dissolve into the droplets.

These droplets eventually contaminate the groundwater that feeds wells for nearby houses and filters into the reservoir and creek.

This contamination prompted the Central Valley Regional Water Quality Control Board to issue a cease-and-desist order last month, directing mine officials to stop polluting the water.

Two years ago, the board issued the first such order, but both parties agreed to work together.

"We worked with them for years and years, and they pretty much denied there was a problem," Schwab said. "They have to monitor the site until we decide there's no longer a threat to water quality. That's based on the law."

But Pete Dwelley, director of regulatory affairs for Meridian Beartrack Company, accused Schwab and the Regional Water Board of blaming the mine for a problem beyond the company's control.

"Their staff is saying the changes in water quality is due to the mining," Dwelley said. "We're saying, 'no, it's a natural phenomenon.'"

Dwelley cited research by his own staff as well as a California State University, Fresno, professor that supports his position.

"There is naturally occurring arsenic in the water all up and down the Mother Lode," Dwelley said.

"There are many wells that had arsenic in them way before the mine."

While Schwab agreed the water in the foothills has a lot of minerals dissolved into it, she said pollution from the gold mine made the situation worse.

Dwelley said his company will appeal the Regional Water Board's decision to the California Water Quality Control Board, which oversees all regional water boards in the state. The California board should hear his case sometime this summer.

If Dwelley prevails, his company will only have to pay about $5 million more than the $20 million already spent to finish cleaning up the site.

If the State Water Board agrees with the Regional Water Board's conclusion, Dwelley said Meridian Beartrack Company will have to spend about $35 million more on a 250-acre plastic cap to cover the pit and prevent rain water from running in.

Contact Genevieve Bookwalter at