BOARD AGENDA MEMORANDUM
Government Code § 84308 Applies: Yes ☐ No ☒
(If “YES” Complete Attachment A - Gov. Code § 84308)
SUBJECT: Title
Receive an Update on Golden Mussel Detection in California and Santa Clara Valley Water District’s Response.
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RECOMMENDATION: Recommendation
Receive an update and provide feedback on Santa Clara Valley Water District’s response to the threat of golden mussels in California.
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SUMMARY:
Since 2008, Santa Clara Valley Water District (Valley Water), in partnership with Santa Clara County Parks, has implemented an invasive species prevention program to protect its infrastructure from potential infestation by quagga and zebra mussels. Following the discovery of golden mussels in October 2024 in the Sacramento-San Joaquin Delta, Valley Water staff developed a multi-pronged response. This response includes establishing an internal workgroup, coordinating with partner agencies, and launching an outreach and educational campaign. The Board most recently received an informational update through a CEO Bulletin dated May 8, 2026.
Background
Golden mussels pose significant ecological and operational risks to California. These invasive species can rapidly colonize hard surfaces, clogging water intakes, screens, and pipelines. Their spread threatens native aquatic species, damages ecosystems, and jeopardizes the long-term reliability of water delivery infrastructure.
In response, Valley Water has coordinated closely with the California Department of Fish and Wildlife, the Department of Water Resources, Santa Clara County Parks, and other partners to assess the extent of the infestation and implement preventive measures. Actions completed to date include:
• Expanding invasive mussel monitoring efforts to include golden mussels
• Suspending water transfers from San Luis Reservoir to Calero Reservoir during the golden mussel breeding season
• Initiating voluntary vessel exit inspections at Calero and Coyote reservoirs
In addition, Valley Water launched a comprehensive public education and outreach campaign this month to raise community awareness about the risks posed by golden mussels and the importance of prevention.
Valley Water has also completed a comprehensive infrastructure vulnerability assessment, with support from a specialized consultant, to identify facilities at risk and develop strategies. Staff are actively implementing recommended mitigation measures.
Valley Water will continue to collaborate with regional partners to reduce the risk of introduction and spread while advancing protection measures. As this situation continues to evolve, Valley Water remains committed to monitoring conditions, protecting the ecosystem and water infrastructure, and providing regular updates to the Board.
ENVIRONMENTAL JUSTICE IMPACT:
There is no environmental justice impacts associated with this agenda item.
FINANCIAL IMPACT:
The full financial impact of Valley Water’s response to golden mussels is not yet known. Staff are conducting additional analysis and will provide an update to the Board when more information becomes available.
CEQA:
The recommended action does not constitute a project under CEQA because it does not have the potential to result in direct or reasonably foreseeable indirect physical change in the environment.
ATTACHMENTS:
Attachment 1: PowerPoint
UNCLASSIFIED MANAGER: Manager
Sam Bogale, 408-630-3505