‘It is absolutely a big problem’
California’s San Joaquin Valley is facing a growing challenge as water agencies grapple with an influx of golden mussels, an invasive species rapidly spreading through the state’s waterways.
A Growing Threat to Water Infrastructure
Water agencies throughout the San Joaquin Valley, from Stockton to Arvin, have discovered golden mussels clogging pipes and equipment. The Arvin-Edison Water Storage District first detected the mussels in its system in December 2025, prompting a thorough inspection of the Friant-Kern Canal by the Friant Water Authority. A significant presence of the invasive species was found, and efforts to remove them began immediately.
Protecting the upper watershed of the San Joaquin River and Millerton Lake is considered vital to safeguarding the entire Friant system. However, controlling the spread is proving difficult. Golden mussels spawn multiple times a year and can enter a protective state, effectively shielding themselves from chemical treatments. Currently, no effective chemical defense has been identified.
Why the Concern?
Golden mussels pose a significant threat to both ecological and economic stability. Originating in China, this highly invasive species has already caused substantial damage in South America, displacing native mollusks and disrupting river ecosystems. In California, the mussels degrade water quality and have prompted stricter boat inspections, such as those implemented in Lake Tahoe, to prevent further spread.
The primary concern for California’s agricultural sector is the mussels’ tendency to clog small-diameter pipes, potentially disrupting water deliveries to farms. This could lead to reduced crop production and increased food prices.
What Steps Are Being Taken?
California has a Golden Mussel Response Framework in place, outlining the current understanding of the species and strategies to slow its spread. The Bureau of Reclamation and other agencies are actively monitoring the situation. However, water agencies have indicated that these measures are insufficient and are seeking financial assistance from state and federal governments to support eradication efforts.
Promising approaches, including ozone treatment and ultraviolet radiation, are currently under review as potential eradication methods.
Frequently Asked Questions
What are golden mussels?
Golden mussels are an invasive species originating in China that are rapidly spreading through California’s waterways, causing problems for water infrastructure and ecosystems.
Where have golden mussels been found in California?
Golden mussels have been discovered clogging pipes and equipment from Stockton to Arvin in the San Joaquin Valley, and have also been found in the Sacramento-San Joaquin Delta and Lake Tahoe.
Why are water agencies concerned about golden mussels?
Water agencies are concerned because golden mussels can clog small-diameter pipes, potentially disrupting water deliveries to farms and communities, and they are difficult to eradicate due to their reproductive rate and resistance to chemical treatments.
As California water agencies continue to battle this invasive species, what long-term strategies will be necessary to protect the state’s vital water resources?