Date: March 14, 2003

Preventing groundwater contamination
is focus of weeklong campaign

SAN JOSE – At more than 600 sites throughout Santa Clara County, the gasoline additive MTBE threatens to invade underground drinking water supplies. Recent testing is finding low levels of a contaminant known as perchlorate in hundreds of South County wells.

Consider that the county’s groundwater basins supply half of our annual drinking water supply and it isn’t hard to imagine a disaster waiting to happen.

Fortunately, municipalities that operate their own drinking water systems, as well as the county’s retail water companies, regularly test wells for contamination. And the Santa Clara Valley Water District monitors groundwater quality by sampling water from a number of deep wells located throughout the county.
But, because there is no local, regional or state agency responsible for maintaining and testing the county’s 5,000 private wells, it’s up to owners to watch over them.
That is the message in an annual weeklong campaign that urges private well owners to maintain their systems and to test their wells annually for contaminants.

The campaign – known as National Ground Water Awareness Week, March 16-22 – advocates annual water well “checkups,” including maintenance inspection and water-testing.

“As we say at the district, ‘If you don’t want to drink it, don’t put it on or in the ground,’ “ said Sig Sanchez, chairman of the Santa Clara Valley Water District board of directors. “Protecting our groundwater basins from contamination is the responsibility of everybody living and working in Santa Clara County.”

Roughly half of the county’s annual drinking water supply is pumped from groundwater basins through wells owned by municipalities, retail water companies or individuals. Water from groundwater basins has traditionally been of very high quality. However, the basins are threatened by industrial spills, urban runoff, leaking underground fuel storage tanks and agricultural operations, as well as biological pathogens from cracked sewer lines, septic systems, livestock facilities and other sources.

The district recommends an annual checkup of private well systems, including:

• Inspection of the wellhead, looking for openings that insects, rodents, water or anything else can enter.

• Inspection for cracks in the concrete pad that would allow water or contaminants it may be carrying to follow the well casing into a drinking water aquifer.

• Inspection for water flowing out of the top of the well, which can waste water and/or allow contaminants in.

• Clearing away overgrown vegetation and debris, which can create homes for rodents and other pests. (Do not use herbicides around your well.)

• Making sure the well-registration number is still visible, as locally required.

To maintain water quality, there are dozens of tests that can be performed on drinking water and no one analysis can assure that water from a specific well is “safe to drink.” For that reason, the water district recommends that well owners have samples tested by certified laboratories for:

• Total coliform bacteria, the presence of which indicates that the water may be contaminated with other disease-causing organisms.

• Nitrate, a naturally occurring compound that, at high levels, is a health risk for infants younger than 6 months of age, pregnant women and people with certain specific enzyme deficiencies.

• Electrical conductance, or EC, a measure of all the dissolved ions in the water that can be used an indicator of changing conditions that may require further testing.
For more information about groundwater protection and proper well maintenance, read “A Guide for the Private Well Owner” by logging onto www.valleywater.org.

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.