The Abridged version:
- After first being detected in 2024, invasive golden mussels have spread rapidly in California, recently reaching the Port of West Sacramento.
- So far, eradication efforts have been unsuccessful at stemming the tide, and water managers have leaned on prevention and education to keep the mollusks from spreading to new bodies of water.
- One water district in Kern County recently used a copper treatment to effectively kill golden mussels.
Since invasive golden mussels arrived in California a couple of years ago, officials up and down the state have scrambled to come up with solutions to their rapid spread.
For months, state and local water agencies tried things like hot water treatments and scraping of docks. But the hardy mollusks, which are native to Asia and were likely brought to the California Delta on the hull of a ship, continued to circulate.
By early July, they had established populations as far south as San Diego and as far north as the Port of West Sacramento.
For the most part, efforts to eradicate the newly established species fell short. Instead, statewide water managers leaned on prevention and education, hoping to stem the movement of mussels between bodies of water by imposing boat hull inspections and cleaning protocols at lakes and reservoirs.
Recently, though, a water district in Kern County used a copper treatment to effectively kill golden mussels that had established themselves locally. Officials said the move, which worked on full-grown mussels and ones that had not yet attached, represents a tool for water managers in the battle against the destructive species.
‘Maximum mortality of mussels’
The Arvin-Edison Water Storage District, which sits southeast of Bakersfield, began treating its water with a product called Natrix CA in March. The compound is a liquid-based molluscicide that gets poured directly into water to kill mussels.
According to an announcement the district made in March, the first phase included an “aggressive systemwide treatment to achieve maximum mortality of mussels,” followed by an ongoing effort to wipe out incoming mussel larvae.
To do that, Arvin-Edison used a high dose of copper treatment, said Gary Pitzer, a spokesperson for the California Department of Water Resources.
That proved effective for killing mussels, but the state agency is trying something else.
“DWR is implementing a different approach in the State Water Project; continuous low-dose copper injection into at-risk small diameter pipelines to prevent the settlement of mussels in the first place,” Pitzer said in an email.
Although copper sulfate products, including Natrix CA, are approved for use in California, permits are required for their use. The products can be dangerous if ingested in high concentrations.
The Natrix CA label says the product is safe to use on crops, Arvin-Edison said in its announcement.
Daniel Hennessy is a reporter covering Yolo County for Abridged by PBS KVIE. He joined Abridged through the California Local News Fellowship.