Date: Sept. 25, 2003

Emergency switch in water sources temporarily affecting taste, odor of tap water in San Jose

SAN JOSE - Some people in the Almaden Valley, Santa Teresa and the Evergreen areas of San Jose may taste or smell something resembling rotten eggs in their tap water. But the aesthetic nuisance, according to Santa Clara Valley Water District officials, is temporary and poses no risk to consumers' health.

The rotten-egg odor is the result of using water from Calero Reservoir to feed the Santa Teresa Water Treatment Plant for treatment and delivery to customers of San Jose Water Co. and the San José Municipal Water System. Warm temperatures and low water conditions in the reservoir have resulted in a lack of oxygen in the untreated water, which produces hydrogen sulfide. The resulting rotten-egg smell cannot be fully eliminated in the treatment process.

Calero Reservoir was pressed into service Wednesday night following a sewage spill in Morgan Hill that threatened to enter Anderson Reservoir. Although Anderson has been given a clean bill of health and is once again serving the Santa Teresa plant, water already sent to Santa Teresa from Calero will continue to affect the taste and odor of water deliveries until later tonight or early Friday morning.

Despite the bad taste or smell, the water is safe to drink.

The water district normally has several sources of water from which to choose in order to serve the highest quality and best-tasting water possible. This time of year, the district usually imports water from San Luis Reservoir. However, the reservoir is "off-line" for scheduled maintenance. Until the maintenance is completed, the district opted to use water from Anderson Reservoir.

But the district chose to shut down Anderson Reservoir late Wednesday when a resident discovered raw sewage spilling from a pump station in the Holiday Lake Estates neighborhood in northeast Morgan Hill. Until further information could be obtained, the district immediately stopped receiving Anderson Reservoir water and began treating Calero Reservoir water. The deeper water in Calero Reservoir is completely without oxygen this time of year, causing the rotten-egg odor.

Further investigation into the Morgan Hill sewage spill confirmed Thursday that none of the effluent reached Anderson Reservoir.

Over the next few years, the water district will complete significant construction at all three of the treatment plants serving Santa Clara County. The facilities will use state-of-the-art ozone treatment which is considered the most effective means for eliminating bad tastes and odors from drinking water.

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.