Residue in water raises questions in Copper

December 03, 2002 11:00 pm

By SCOTT PESZNECKER

A two-year-old state study shows copper levels in some streams near the historic area of Copperopolis are 10 times higher than what the state considers safe.

However, the study was only released last month, and only after a former Calaveras County planning commissioner pushed for answers.

A letter sent when the study was released from a senior geologist for the state Regional Water Quality Control Board indicates "a significant threat to water quality" and aquatic life. When contacted, the geologist, Victor Izzo, said that whether the copper levels are hazardous to humans has yet to be determined.

He also said his department was too overworked to look at the study data at the time it was compiled.

Now, state and county officials want to know if old copper tailings — leftover mining rocks — found in water and soil near the Copperopolis fire house are damaging the drinking water that comes from Tulloch Reservoir.

The reservoir supplies drinking water to thousands of nearby residents.

Water and soil tests conducted near the tailings two years ago by the state water quality board shows what the state calls hazardous amounts of copper leaching from the leftover rocks every time it rains.

The tailings are at least 50 years old.

According to the state study, safe levels of copper in water and soil are 25 mg per liter and 2,500 mg per kilogram, respectively.

The water sample collected contained 250 mg per liter of copper, and two soil samples yielded 2,600 and 3,800 mg per kilogram.

Only in November, at the request of Copperopolis resident and businessman Ed Rich, did the state dig out the data and release its findings.

Despite the "significant threat to water quality" noted in his letter, Izzo — a senior engineering geologist for the state board — said he doesn't know if the tailings' byproducts are dangerous to people.