If you can’t beat ’em, control ’em.
That might be the best strategy for tackling the scourge of golden mussels that have quickly spread across the Delta and throughout California’s lakes and inland waterways, causing millions of dollars in damage.
Help may now be on the way for boat owners, farmers and water company managers eager for a solution to ward off the quickly propagating bivalves.
A Davis-based company is readying a test in Stockton of a biodegradable treatment that kills golden mussels without damaging surrounding aquatic wildlife.
The biobased product, Zequanox, is already being used on quagga and zebra mussels, two other invaders that have bedeviled the nation over the past few years.
Invasive Species Corp., the company that makes Zequanox, is working to seek approval from the U.S. Environmental Protection Agency for relabeling to include its effectiveness and safety in dealing with golden mussels, said Pam Marrone, the company’s executive chair and co-founder.
“We’re working as fast as we can to get the new formulation to the EPA,” Marrone said.
Zequanox uses a microorganism, a type of bacteria, that kills the offending mussels without injuring other surrounding aquatic life. It’s billed as a safer solution to stop the spread of mussels than copper-based products, which have been used on crops. Marrone, who is also an entomologist, said besides being biodegradable, Zequanox requires less treatment time.
While no strategies have emerged to completely eradicate golden mussels from California, Marrone said Zequanox has shown effectiveness in killing zebra mussels in large lakes. She touts its successful use in 40-acre Deep Quarry Lake in Wayne Township, Illinois, in 2012. Two years later, the 265-acre Christmas Lake in Shorewood, Minnesota, was successfully treated.
To show what it can do against golden mussels in the Delta, the product will be tested in the local marina that’s home to the Stockton Sailing Club on Buckley Cove Way this fall.
“We’re going to treat some boat slips,” Marrone said. “We’re getting water curtains (to cordon off the slips) and will do a trial with our tablets, powder and granules.” The test will see which form is most effective for a marina application.
Success could spell relief for boat owners worried about golden mussels fouling propellers, hulls and clogging engine cooling or plumbing lines. Farmers, too, are dealing with the tiny mussels plugging irrigation lines.
Golden mussels present a threat to the general public as well, with the potential to foul Stockton’s water supply.
The Stockton City Council passed an emergency declaration in June to try to hasten control of golden mussels. It came after the council was informed the bivalves are clogging the city’s water intake pipes. The equipment was found to be 30% to 40% backed up, the Municipal Utilities Department reported. The city planned to spend $209,000 to clean it.
San Joaquin County also passed an emergency declaration, initially in April. The Board of Supervisors voted earlier this month to extend the order.
To the south, Kern County — which has already spent $9 million fighting a golden mussel invasion — estimates the infestation is going to end up costing $36 million a year.
The crisis has unfolded in less than two years. Golden mussels were first discovered in California at the Port of Stockton in October 2024. They were believed to have hitchhiked from Asia in the ballast water of a ship. Though little more than an inch long, they easily reproduce by the millions.
Since the initial discovery, the invaders have spread quickly across California’s inland waters. The expansion has been so quick and extensive, the bivalves were even detected near a dam in San Diego County, not far from the Mexican border.
The fight to try to slow the spread has resulted in such measures as inspections of boats before they launch, especially at treasured sites like Lake Tahoe. In the state’s largest reservoir, Lake Oroville, it was announced in April that inspections were being suspended in the belief that the water temperatures stay cool enough to quell mussel growth.
Zequanox-maker Invasive Species Corp. has also partnered with a Missoula, Montana-based distributor, ClearChannelVM, that has expertise in working with irrigation customers.
Linking up with Invasive Species was important because treating golden mussels requires a different approach than what is used against pests in farming and other commercial water sources, said Andrew Skibo, ClearChannelVM’s founder and president. Lakes and streams that are used for drinking water need control methods that won’t harm humans.
He underscored that a solution is badly needed.
“Golden mussels represent an existential threat to California irrigators and waterways,” Skibo said.