California’s Office of Emergency Services denied Kern County’s request for a statewide emergency declaration over the golden mussel invasion. Local water agencies estimate their response costs at more than $36 million a year; that figure is an annual estimate, not a single unpaid bill. The denial leaves agencies facing those costs without the state declaration the county sought.
Cal OES said it had not identified a long-term way to eliminate or control the invasion, according to SJV Water. The agency’s guidance says California Disaster Assistance Act funding for damaged public property may be made available after either a local-government emergency proclamation or a governor’s state-of-emergency declaration, according to the California Governor's Office of Emergency Services. A statewide declaration is therefore not the only trigger described in the guidance, though it does not mean every mussel-response expense qualifies.
Kern County Supervisor Jeff Flores, who helped lead the push for a countywide emergency declaration, said farmers need reimbursement for their costs and help finding an actual fix, per the same account. He said he plans to keep pressing the issue once a new administration takes office, noting that Governor Gavin Newsom is termed out and that Xavier Becerra and Steve Hilton have both been mentioned as possible successors. In the meantime, Flores advised residents and agencies to track their costs and document their response efforts in case funding becomes available down the line.
Mussels Keep Arriving With Every Water Delivery
The core problem, as the state frames it, isn't that local agencies can't fight the mussels within their own systems — it's that they can't stop new ones from showing up. New mollusks arrive with every water delivery pulled through the state and federal systems that export water from the Sacramento-San Joaquin Delta, the article notes, where golden mussels are now entrenched. From there, the species has spread hundreds of miles through California's interconnected waterways, according to the Sacramento Bee.
The invasion has a short but fast-moving history. The mussels were first discovered in North America at the Port of Stockton in 2024, and by late June the California Department of Fish and Wildlife had confirmed them as far north as the Port of West Sacramento, according to Agri-Pulse. They've also moved south through the State Water Project, lodging inside infrastructure that delivers water to farms and cities, including Kern County, which the SJV Water report identifies as the second-largest contractor for state water. The California Department of Fish and Wildlife warns the mussels can clog water infrastructure and reduce flow, with potential consequences for agriculture, home water deliveries and flood control, as reported by Stocktonia.
Wheeler Ridge-Maricopa's Pipeline Reinfestation
Local agencies are finding that even hard-won progress doesn't last. Wheeler Ridge-Maricopa Water Storage District discovered new infestations in its pipeline system that had been mostly mussel-free the previous year, per SJV Water's reporting, which cited general manager Sheridan Nicholas. The district had already spent $560,000 treating its canals and expects to need additional pipeline treatment in 2027.
Arvin-Edison Water Storage District has been combatting golden mussels since earlier this year as well. Resource manager Sam Blue called the state's response disappointing, saying California is failing to protect vital infrastructure, according to the same report. Some Kern County water managers have floated a low-dose copper treatment of California Aqueduct water to kill the mussels' larvae, known as veligers, and protect contractors downstream.
Why a Full-Scale Fix Is So Expensive
The state has already run the numbers on a larger-scale treatment, and they're steep. Department of Water Resources spokesman Gary Pitzer said in an email last summer that copper treatment of aqueduct water would not be feasible, and more recently told the outlet that there is currently no feasible or cost-effective method for eliminating veligers from water conveyed through the State Water Project. One proposal to treat the aqueduct — which moves Delta water south to farms and cities — would require 30 chemical application stations spread across 300 miles at a flow of 3,000 cubic feet per second, with chemicals alone estimated to cost $424 million for just one application.
Those figures echo broader statewide estimates. The Association of California Water Agencies has projected that routine inspections at a single State Water Project reservoir could exceed $12 million annually, with statewide golden mussel management ultimately reaching $300 million to $500 million, according to Agri-Pulse. The enacted state budget sets aside $6 million for golden mussel decontamination facilities in the Delta along with ongoing response funding, the outlet reports — a fraction of what full-scale containment could eventually cost.
Other Counties Have Already Declared Emergencies
Kern isn't the only county that has tried this route, though its request to the state went nowhere. San Joaquin, Sacramento and Yolo counties have each declared their own local emergencies over golden mussels, SJV Water reports. San Joaquin County first proclaimed its local emergency on April 28 and extended it on June 16, according to San Joaquin County. Sacramento County's Board of Supervisors followed suit with its own declaration on June 16, per the Sacramento Bee.
Kern County’s Board of Supervisors declared a local state of emergency over the mussels at its May 12 meeting, according to The Bakersfield Californian. Cal OES guidance says a local-government proclamation can make CDAA funding available, but only for eligible costs; the county’s separate request for a statewide declaration was denied. Cal OES declared an emergency over possible El Niño-fueled winter storms in September.
What state aid rules and past responses show
Cal OES says CDAA funding may be made available after a local-government emergency proclamation or a governor’s declaration, for repair, restoration or replacement of public property damaged or destroyed in an emergency. The state share is generally no more than 75% of eligible costs, according to California Governor’s Office of Emergency Services guidance. The rules describe potential assistance, not automatic reimbursement for all response spending. For context, California’s Golden Mussel Response Framework records the species’ discovery in the Sacramento-San Joaquin Delta in October 2024 as its first known occurrence in North America. A different invasive species prompted an earlier response: the California Department of Fish and Wildlife says quagga mussels were discovered at Lake Mead in January 2007 and found at a Metropolitan Water District diversion intake in Lake Havasu, prompting a CDFW-led incident command response. That episode involved a different mussel species and facilities from Kern County’s current golden-mussel problem.
One possible workaround exists on the regulatory side. Local water agencies could obtain emergency permits for one-time heavy mussel treatments without undergoing California Environmental Quality Act review, but ongoing treatment efforts may still require full CEQA study, which SJV Water describes as a time-consuming and expensive process. Local water managers can tamp down infestations within their own systems, but as long as new mussels keep arriving with every Delta water delivery, full eradication remains out of reach. SJV Water said it contacted CalOES with questions for its report but had not received a response before publication.
