Monday May 11, 2026
The Mercury News —
For the first time, golden mussels, an invasive species of tiny mollusks that can rapidly reproduce and cause millions of dollars in damage to pipes, drinking water plants, irrigation systems and dams — sparking growing concerns across California — have been found in Santa Clara County.
Last month, a juvenile golden mussel was discovered in the raw water intake area at the Penitencia Water Treatment plant near Alum Rock Park in San Jose. A few weeks later, in late April, an adult was found in a raw water strainer at the Santa Teresa Water Treatment Plant in San Jose’s Almaden area.
The water remains safe to drink, say officials at the Santa Clara Valley Water District, which owns the plants and provides water to 2 million residents of Silicon Valley.
But the discovery of the diminutive invaders has alarmed local officials, who say they must now install equipment costing hundreds of thousands of dollars at some district facilities to remove them, step up inspection rules for boaters on local reservoirs and limit the way more than dozen groundwater recharge ponds are used this year.