A nontoxic alga in the water supply is causing concern for many Los Altos residents.
The Santa Clara Valley Water District assured consumers that the water still “meets or surpasses drinking-water standards” despite a bloom of geosmin in the Central Valley’s San Luis Reservoir.
Geosmin, a compound whose name comes from the Greek words for “earth odor,” is safe for humans, but its scent is noticeable even in trace amounts. The smell is often compared to a rainy field or fresh beets.
“It is the season for it,” said water district spokeswoman Colleen Valles. “The warmer weather and lower water levels in various reservoirs can contribute to the development of algae.”
Los Altos relies on the Rinconada Water Treatment Plant in Los Gatos, according to Valles. In 2015, the water district began a Reliability Improvement Project at Rinconada to bring it in line with the other two plants in Santa Clara Valley.
“The Santa Teresa and Penitencia water treatment plants use ozone” to eliminate geosmin and its scent, Valles said. “Part of Rinconada’s reliability upgrade is to add ozone. … It instead uses powdered activated carbon. That brings the geosmin detectability levels down, but not quite to the levels of ozone.”
The water district July 6 switched its source to the Anderson Reservoir on the Santa Clara side of the Diablo Range. Scott Povio of California Water Service said the smell will “completely dissipate” soon.
“We have to move the water through the system, and with people conserving so much water, it takes longer to go through the system,” he added.
While the alga-affected water flushed through Los Altos, many residents expressed concern over their water. But both the water district and Cal Water assured consumers that geosmin is nontoxic, even if it might smell and taste a bit strange.
“Everything is safe to drink,” Povio said. “We continue to do our routine testing daily.”
For more information, visit calwater.com/los-altos-taste-and-odor-issue.
