Invasive Golden Mussels Detected at San Jose Water Treatment Plants
Water officials in Santa Clara County are on high alert following the first-ever detection of golden mussels within the region’s water infrastructure. These tiny, invasive mollusks are known for their ability to reproduce rapidly and cause extensive damage to critical water delivery systems, sparking urgent mitigation efforts to protect the area’s utility network.
While the Santa Clara Valley Water District, which serves approximately 2 million Silicon Valley residents, has confirmed that the drinking water remains safe, the discovery highlights a growing threat to California’s water security.
- Locations: Golden mussels were found at the Penitencia Water Treatment plant and the Santa Teresa Water Treatment Plant.
- Impact: The invaders can clog pipes, pumps and dams, potentially leading to millions of dollars in infrastructure damage.
- Water Safety: Officials confirm the drinking water remains safe for public consumption.
- Prevention: Boaters and anglers are urged to follow “Clean, Drain, and Dry” protocols to prevent further spread.
What Are Golden Mussels and Why Are They Dangerous?
Golden mussels are an invasive species native to Asia. They are characterized by their ability to grow in dense layers, which allows them to effectively clog pipes, pumps, and other essential water equipment. In California, these mussels were first detected in the Delta in 2024 and have since spread to various waterbodies connected to the Sacramento-San Joaquin Delta, including the San Luis Reservoir.
These mollusks are particularly difficult to control because they spread through several vectors. They can attach themselves to boats, plants, and recreational gear. Their microscopic larvae can be transported in bait buckets, bilges, or live wells, allowing them to move from infested waters to clean environments with ease.
The Discovery in San Jose
The detection in Santa Clara County occurred in two separate instances during the spring of 2026:
- Penitencia Water Treatment Plant: A juvenile golden mussel was discovered in the raw water intake area near Alum Rock Park.
- Santa Teresa Water Treatment Plant: An adult mussel was found in a raw water strainer in San Jose’s Almaden area.
The discovery has prompted immediate concern among utility leaders. Jason Araujo, a utility maintenance manager with the Santa Clara Valley Water District, noted that while only two mussels have been detected so far, it suggests more may be arriving. “It’s not out of control yet, but as the season goes on, they could be multiplying a lot more,” Araujo stated.
Infrastructure Risks and Economic Impact
The primary threat posed by golden mussels is economic and operational rather than biological. Because they adhere to hard surfaces in dense clusters, they can obstruct the flow of water and damage irrigation systems, dams, and treatment plants. Once established, the cost of containment and repair can soar into the millions of dollars.
In response to the San Jose findings, local officials are now implementing several emergency measures:
- Equipment Upgrades: The district must install new equipment at certain facilities to remove the mussels, a process costing hundreds of thousands of dollars.
- Operational Limits: Use of more than a dozen groundwater recharge ponds will be limited this year.
- Increased Surveillance: Inspection rules for boaters on local reservoirs are being intensified.
How the Public Can Help Prevent Spread
Although golden mussels have been found at treatment plants, they have not yet been detected in any of the Valley Water reservoirs in Santa Clara County. Preventing their entry into these reservoirs is a top priority for the district and Santa Clara County Parks.
Residents and visitors can help stop the spread by following these guidelines:
- Boaters: Strictly adhere to the “Clean, Drain, and Dry” protocol before entering or leaving any body of water.
- Anglers: Avoid using wet live bait and do not transfer bait or water between different water bodies.
- Reporting: Any suspected sightings of golden mussels should be reported immediately to the California Department of Fish and Wildlife.
Frequently Asked Questions
Is my tap water safe to drink?
Yes. Officials from the Santa Clara Valley Water District have explicitly stated that the drinking water remains safe despite the presence of mussels in the raw water intake areas.
Where did golden mussels come from?
Golden mussels are native to Asia and were first identified in California’s Delta region in 2024.
Why is this considered an emergency?
While they don’t affect water potability, their ability to rapidly clog industrial pipes and pumps can lead to massive infrastructure failure and extremely high repair costs.
As California continues to battle this invasive species, the focus remains on aggressive prevention and early detection to ensure the stability of the state’s water delivery systems.