Contra Costa pilots UV and filtration to shield critical pumps from golden mussel invasion

Contra Costa pilots UV and filtration to shield critical pumps from golden mussel invasionFaced with a rapidly spreading invasive species in the Sacramento-San Joaquin Delta, the Californian utility is adding mitigation projects to its capital improvement plan to protect vulnerable cooling lines on its large-capacity pumps.

Golden mussels have been detected at several CCWD facilities, including a recent eDNA hit at the Los Vaqueros Reservoir.

The invasive species specifically threatens small-diameter piping used to cool large, long-lead-time pumps at the district's intakes.

CCWD has spent $217,000 on response efforts to date, with an additional $725,000 anticipated through the end of fiscal year 2026.

The utility is piloting in-house fabricated filtration devices and partnering with the University of Toronto to test UV treatment systems.

Contra Costa Water District (CCWD) is accelerating efforts to protect its primary intake and pumping infrastructure from a rapidly spreading golden mussel invasion, adding new mitigation measures to its upcoming capital improvement program. During an April 15, 2026, board meeting, Water Operations Manager Daniel McVay reported that the invasive species, first found in the Delta in late 2024, has now been detected at the district's Old River and Middle River pump stations, as well as the Contra Loma and Mallard reservoirs. Last month, the district also recorded an eDNA PCR hit for golden mussels at the Los Vaqueros Reservoir. The primary infrastructure vulnerability lies in the small-diameter piping used to cool the motors and pumps at CCWD's intake facilities. A board member noted that if these vital cooling lines clog, it could damage the district's largest capacity pumps, which take years to fabricate and replace, thereby threatening the overall reliability of water drawn from the Delta. To combat the threat, CCWD's maintenance team has doubled its inspection and cleaning cycles and is currently piloting in-house fabricated filtration devices plumbed directly into the pumps at the Old River facility. The district is also evaluating alternative piping materials and replacing vulnerable water quality instrumentation with water quality sondes that require less maintenance. Further technological interventions are on the horizon. CCWD is partnering with the University of Toronto to pilot a four-inch UV treatment system at one of its intakes, with hopes of eventually utilizing UV technology to protect pump and motor cooling lines. The district is also exploring hot water systems to flush and clear small-diameter pipelines, while continuing to apply copper-based treatments at the headworks of its treatment plants—a measure that has successfully prevented the mussels from establishing themselves in the treatment facilities to date. The response program carries immediate financial implications. CCWD has spent $217,000 on its golden mussel response so far and anticipates spending an additional $725,000 through the end of fiscal year 2026. McVay indicated that ongoing operational costs could range from $100,000 to $300,000, and golden mussel mitigation projects have been officially added to the fiscal year 2027 Capital Improvement Program. To help offset costs, the utility has secured $130,000 from the Water Research Foundation and $72,000 from the Bureau of Reclamation, and is currently pursuing a $2 million federal grant appropriation to further study the species and protect utility infrastructure.