A polluted North County creek that turns bright orange-red during rainstorms will be running clear again, thanks to the U.S. Environmental Protection Agencyâ€™s decision to take over the cleanup of two abandoned mercury mines.
The Klau/Buena Vista Mine in the Adelaide area near Paso Robles has now been declared a federal Superfund site, after years of mercury pollution of Las Tablas Creek and Lake Nacimiento. The U.S. EPA has already removed some contaminated materials during emergency action to stabilize the old mine site a few years ago.
â€œThe site will continue to pose a threat for years, so operation and maintenance is required into the future,â€? explains David Schwartzbart, an engineering geologist with the Regional Water Quality Control Board. â€œDeclaring it a Superfund site allows the EPA to take the lead on complete remediation, plus operation and maintenance.â€?
Mine waste was also used to build nearby roads, which have been found to contain mercury, nickel, iron and other metals in â€œfairly high concentrations,â€? 100 times higher than drinking water standards. After rains, potholes in the road next to the creek fill with water that becomes highly acidic and reddish colored, says the geologist.
The Water Board has been negotiating unsuccessfully over the cleanup with mine owner Harold Biaggini since 1968, including various state and federal criminal and civil cases against Buena Vista Mines, Inc. â€œWe did everything we could do to get Buena Vista Mines, Inc. to do the right thing. Some larger entity had to come in and take over the work weâ€™ve done,â€? says Schwartzbart.
Contaminated run-off flows into Lake Nacimiento, where bottom sediments are rich in toxic mercury. The California Department of Fish and Game issues warnings in its fishing license booklets about mercury levels in Nacimiento fish, and county health officials have also posted warnings about limiting fish consumption because of the toxin.
Mercury has not been found dissolved in the lake water column unless sediments are stirred up, he says. â€œAny intake for a Nacimiento pipeline has to be appropriately designed so it doesnâ€™t stir up the bottom sediments,â€? he adds.
The EPA will now start assessing the extent of mercury in the soil and water at the mine site, and preparing for the long-term stabilization and remediation of the old mines. So far, itâ€™s not known how much the project will cost. â€œWhy should anyone care about the cleanup?,â€? asks Scwartzbart. â€œBecause itâ€™s ugly, hazardous, and polluting one of our pristine, beautiful areas.â€?
From 1868 through 1970, the Buena Vista and adjacent Klau mine were a source of cinnabar mercury, which was mined and processed at the site. Processing equipment, flasks, trucks and other facilities are still present, covered with rust. If liability issues can be resolved, Schwartzbart would like to see the reclaimed site turned into a historical museum. â€œMercury, chromium, gold, and copper mining were a cornerstone of San Luis Obispo Countyâ€™s history,â€? he notes.