Date: March 28, 2003

Water district to begin a million-dollar study
to reduce mercury pollution

SAN JOSE – The Santa Clara Valley Water District has signed a memorandum of understanding with the San Francisco Bay Regional Water Quality Control Board, paving the way for a $1 million study to help reduce mercury contamination in affected streams in the Guadalupe Watershed of Santa Clara County, from the Santa Cruz mountains to San Francisco Bay.

“Mercury is a significant problem in San Francisco Bay and in the Guadalupe Watershed, with the Guadalupe River and three of its tributaries identified as being impaired because of mercury pollution,” said Sig Sanchez, chairman of the water district board of directors.

“The study will provide us the technical and scientific basis for our efforts to reduce or clean up mercury in the watershed and the San Francisco Bay.”

Mercury, a naturally occurring element, has been released into the environment through natural erosion and human activities, including Gold Rush-era mining operations and coal- burning to provide energy. When mercury enters water, biological processes can transform it into a highly toxic form of methyl mercury, which is readily absorbed by aquatic plants, fish and wildlife, where it builds up in the food chain.

People are exposed to mercury primarily by eating fish. At high-levels, mercury exposure can affect fetal and adult nervous systems. Public health officials warn Bay Area communities not to consume any fish caught in the Guadalupe River, and some species of fish in San Francisco Bay, because they may contain toxic levels of mercury.

The year-long study, which will include field surveys and chemical analyses, will assess the extent of impairment, and identify and quantify the sources of the pollutant. The study is part of the San Francisco Bay Regional Water Quality Control Board’s effort to develop a Total Maximum Daily Load, or TMDL, program that examines the water quality problem.

The mercury TMDL project will identify and measure the sources of mercury, calculate how much mercury load the system can absorb and still meet water quality standards, and see what controls can be put in place to meet the standards.

“The water district is taking this initiative because, as stewards of streams in Santa Clara County, we are working toward protecting and restoring the waterways to provide a healthy ecosystem for the community,” said Beau Goldie, an assistant operating officer in the water district’s Watershed Management Division.

“Setting the limits for mercury loading is the responsibility of the San Francisco Bay Regional Water Quality Control Board. We are providing the technical resources to ensure that the Regional Board can base these loadings on sound science. We want to help advance the efforts so that action can be taken to address the mercury problem.”

Although elevated mercury levels in the Guadalupe Watershed are believed to be coming from multiple sources, it is to a large part a legacy of the California gold-mining era when mercury was used in the gold-refining process. Mines – such as the New Almaden Mining District, which operated for many years in the upper watershed extracting and processing the mercury ore cinnabar – are known to be a source of mercury in the Guadalupe River system.

The Santa Clara Valley Water District manages Santa Clara County's wholesale drinking water resources, coordinates flood protection for its 1.7 million residents and provides stewardship for the county's 10 reservoirs and more than 700 miles of streams.