The Loma Prietan
July/August 2003
Restoring San Carlos Creek in San Benito County
by Dr. Khalil E. Abu-Saba with the assistance of Michael Stanley-Jones
The New Idria mercury mine, located in San Benito County's eastern Panoche Valley approximately 65 miles southeast of Hollister, discharges toxic pollution into San Carlos Creek, which in turn drains downstream into Silver Creek, Panoche Creek, and the Panoche fan. During moderate rainy seasons, mining pollution flushes from the Panoche fan into the Mendota Wildlife Area, and into the San Joaquin River during heavy rains, where it is eventually carried into the San Francisco Bay Delta.
Acid mine drainage pours into San Carlos Creek from a mine opening at a rate of 10 to 50 gallons per minute, causing severe discoloration of the water and complete destruction of aquatic life for at least five miles downstream. Downstream of the mine site, concentrations of mercury and nickel exceed state water quality objectives. Elevated concentrations of methylmercury--the toxic form of mercury that bioaccumulates in fish and people--may also be in violation of state objectives. As a result of the acidic and toxic discharge, all aquatic life has been killed in a five-mile stretch of the creek.
The upper watershed of San Carlos Creek contains attractive habitat for the California condor, including many small caves and rocky crevices that could serve as nesting sites. Condors formerly inhabited Eastern San Benito County and are now subject to a captive-bred release program at Pinnacles National Monument. Condors could be expected to use toxic San Carlos Creek water for drinking and bathing.
Mendota wetlands are known to convert mercury to methylmercury, creating an exposure danger for predators such as the giant garter snake and San Joaquin kit fox, two federally threatened species. The Mendota Wildlife Area provides important habitat for the western burrowing owl.
Over 90% of the mercury produced in North America came from just two mines in California: New Almaden, in Santa Clara County, and New Idria. Dozens
of other smaller mercury mines dot the Coast Range landscape. Mercury mined in California fueled the Gold Rush because of its use in extracting gold, and helped fight two World Wars, the Korean War, and the Vietnam War, because of its use in munitions and electronics.
Today legacy pollution from mineral extraction impairs the use and improvement of public resources such as fisheries, parks, wetlands, and streams. For example, the lack of a restoration plan for the Mt. Diablo Mercury mine in Contra Costa County has proved to be a stumbling block for the Coastal Conservancy's CALFED proposal to create a tidal wetland downstream of the mine at Marsh Creek. When Santa Clara County purchased New Almaden to create a park, it inherited a share of the responsibility for managing mercury pollution loads impacting the Guadalupe River and the San Francisco Bay. These water bodies carry fish consumption advisories due to the health risks posed by methylmercury contamination. And as a result of 33 years of neglect, the New Idria mine site became an illegal dumping ground for hazardous waste hauled in from Silicon Valley.
In May 2003, the San Benito County Board of Supervisors adopted a proposal to the Central Valley Regional Water Quality Control Board requesting investigation, clean up and abatement of the discharge of pollutants from the New Idria Mercury Mine, in accordance with Porter-Cologne Water Quality Control Act. If responsible parties cannot be compelled to control discharges, the proposal asks the State Water Board to find public funds to remediate the site. Either way, the state needs to address the legacy of mining pollution.
The Sierra Club should campaign for the clean up of San Carlos Creek and the protection of wildlife and people from toxic methylmercury contamination. Establishing responsibility for New Idria discharges would set an example that environmentalists could build upon to further clean up at other sites, including New Almaden and the Guadalupe River watershed.
Dr. Abu-Saba is an environmental consultant for Applied Marine Sciences, Inc. In addition to his work for the County of San Benito at New Idria, he is a planner for the San Francisco Bay Clean Estuary Partnership. From 1998-2001, Dr. Abu-Saba worked for the San Francisco Bay Regional Water Quality Control Board, where he developed the Mercury Total Maximum Daily Load (TMDL) for San Francisco Bay.
Michael Stanley-Jones is California Director of Clean Water Action & Clean Water Fund in San Francisco. He serves as Conservation Chair of the Sierra Club Loma Prieta Chapter.