State Drops Golden Mussel Boat Inspections at Oroville Reservoir, Raising Tri-Valley Concerns

PLEASANTON, California — Pleasanton, located in the Tri-Valley region about 40 miles east of San Francisco in Alameda County, has a population of approximately 80,000 and is home to corporate headquarters including Workday, Clorox, and Safeway.

The California Department of Water Resources is ending a mandatory boat inspection and decontamination program at Lake Oroville, one of the state’s largest and most important reservoirs, despite the ongoing spread of destructive golden mussels through California waterways. The decision follows a state-funded risk assessment that concluded the reservoir faces a lower risk of infestation due to cold water temperatures, low nutrient levels, and fluctuating water levels.

“California is under an epidemic of golden mussels. Like in any epidemic, you got to control the key hubs — or else the war is lost.” — Anthony Ricciardi, Professor of Biology, McGill University

The invasive golden mussel, native to Asia, was first detected in North America in the Sacramento-San Joaquin River Delta in October 2024. Since then, the species has spread through pumps, canals, and aqueducts to irrigation districts across the state, encrusting critical infrastructure. San Joaquin County and Kern County have each declared states of emergency. The larvae can travel through water systems undetected, and adult mussels can survive near-freezing temperatures for weeks, according to researchers.

State officials said the boat inspection program — which cost $7.5 million to launch and $6.5 million per year to operate — severely impacted recreation at the lake. They estimate that treating downstream power plant pipes with ultraviolet light would cost about $1 million. But critics, including McGill University biology professor Anthony Ricciardi, argue that boats remain the primary vector for spreading the mussels to other lakes, and ending inspections increases the risk to water bodies across the state.

“If Lake Oroville does surrender its program and becomes infested with golden mussels it creates an increased risk for all waterbodies. At that point, any watercraft travelling to Berryessa — or anywhere else — from Lake Oroville would essentially be no different than watercraft coming from the Delta.” — Drew Gantner, Manager of Water Resources, Solano County Water Agency

The California Department of Fish and Wildlife, which previously described the inspection investment as money well spent even if it only delayed new introductions, has deferred questions about the Oroville strategy to the Department of Water Resources. The rollback took effect ahead of the summer boating season.

Source: https://calmatters.org/environment/2026/06/golden-mussels-oroville-boating-invasive/