A $3 million eradication of San Justo Reservoir’s zebra mussels will take one to two years to execute once initiated, and it might not commence for several more years because there are no funds dedicated to the project.
It has been nearly eight years since the discovery of invasive zebra mussels at San Justo Reservoir, prompting a closure of the popular fishing hole that doubles as a water source for the San Benito County Water District’s customers.
More than a dozen officials Monday discussed scenarios that could involve an eradication process—using the natural potash substance chosen six years ago—extending well into the 2020s. Federal officials are wrapping up their environmental impact review three years after the water district finished its own local EIR.
Next, involved agencies must devise an eradication plan and obtain funding before they can treat the water.
Lack of progress and clarity on a schedule had Supervisor Anthony Botelho frustrated Monday. He was in attendance at the reservoir tour among local, state and federal officials. Botelho requested a concrete timeline for a plan moving forward, but he learned there are no available short-term funding sources and that even the long-term prospects are not guaranteed.
“I would think there would be a stronger sense of urgency than just studying it,” said Botelho while seated on folding chairs set up in the San Justo parking lot among representatives from the state and U.S. Bureau of Reclamation, which owns the dam and reservoir.
One of those federal representatives was Duane Stroup, deputy area manager from the reclamation bureau. Stroup indicated it’s likely too late for his agency to allocate San Justo eradication funding into the 2018 three-year budget cycle. That would place San Justo on track for possible funding in the 2019 cycle, which spurred officials at Monday’s gathering to discuss pursuit of other avenues such as state funds, philanthropy or federal Homeland Security dollars—with a threat of eco-terrorism in mind.
In addressing the long time frame, including a nearly eight-year closure to the public facility, Stroup underscored the project’s sensitivity due to significant risks of mussels spreading into the regional distribution system. San Justo Reservoir and nearby Ridgemark Golf & Country Club, to a much lesser extent, are the only known places with zebra mussel infestations between here and Texas.
“The risk is so huge that we’re afraid,” Stroup told the group.
Complicating the treatment, it must involve the use of natural substances such as the sodium chloride combination known as potash, noted California Fish & Wildlife environmental scientist Kelley Aubushon, who led Monday’s tour.
She pointed out how some bodies of water elsewhere in the country have employed far more effective treatments such as chlorine, but the federal government requires the use of natural substances.
“You can’t just dump a bunch of chemicals in it,” she said.
Observing such remarks about the science and adding his own points to the conversation was Dr. Dan Molloy, an aquatic invasive species biologist from the University at Albany State University of New York.
Molloy is the patent inventor of Zequanox, what he refers to on his website as “the first green biopesticide for the control of zebra/quagga mussels.” Molloy was interested in potash since it hadn’t been used on a body of water with such volume.
“The world is going to be watching this place,” Molloy said.
San Justo Reservoir has a capacity of more than 10,000 acre-feet, but the water district plans to draw it down to about 3,000 acre-feet in order to maximize treatment efficiency, said Jeff Cattaneo, general manager of the San Benito County Water District.
Once funding is obtained, drawing it down would likely take a year to two years depending on water levels and timing—as the district cycles the reservoir up and down at different points of the year, Cattaneo said.
Aside from funding alternatives, officials discussed an array of potential recreational options moving forward—including the possibility of restricting San Justo to just rental boats to prevent the spreading of mussels similarly to how other water sources have responded—but it was clear that federal and state agencies in particular would proceed with caution.
Zebra mussels are known to catch rides in ballasts of boats that move from one water source to another—which is why lakes and reservoirs throughout the region now have such strict inspection rules for entry—or by latching onto large equipment used in lake settings. The more moisture, the better chance of survival, said Aubushon, the environmental scientist.
They can leave impacts on ecosystems and do severe damage to pipe infrastructure while costing millions, if not billions, of dollars to treat and manage.
Along with the San Justo eradication plan, officials will have to consider an approach to clean the local distribution system, Cattaneo said. There will be additional costs involved with any post-eradication management of San Justo, too.
For now, though, Cattaneo said the water district has adequately managed the mussels in anticipation of an eradication attempt and the mollusks are “not causing a huge issue.”
Cattaneo said the district has been exposing the zebra mussels to air in a process called desiccation—killing off many—and how five years ago the reservoir’s floor was visible due to the highly efficient filter feeders that each take in about a liter of water daily.
“You can see that the water is a lot cloudier now than it was,” Cattaneo said.
Tour insights
Ongoing management was just one of the many themes broached on the tour. The group started with a brief discussion in the parking lot before heading down a boat launch covered in mussel shell pieces, remnants of the receded shoreline.
Aubushon and Cattaneo offered many biological insights as officials asked questions along the shore.
Botelho inquired about temperature considerations, and Cattaneo said colder temperatures would equate to longer treatment times because the mussels would desiccate, or dry out, slower.
“The colder the water is, the longer it’s going to take that potash to be effective,” he said.
As for the treatment itself, the plan calls for up to 51 days of target concentration while the process could take 60 to 90 days for the mussels to all die off, Aubushon said.
The expert went deeper into the life cycle of zebra mussels in responding to Supervisor Jerry Muenzer’s question about birds—and whether they pose a threat as carriers of such invasive mussels from one water body to another.
“If birds were moving them, we would’ve seen a much larger explosion,” she said.
She explained how mussel spawning involves many factors leaving birds as a less likely threat.
As she put it: Mussels are broadcast spawners triggered by heat. They put off sperm and eggs into a water column and fertilize, then suspend in the water for a couple of weeks as free-floating microscopic entities, typically a meter to 10 meters below the surface. They develop a foot and crawl until attaching to something with use of byssal threads and they generally stay put at that point.
Her point was that the mussels’ life stage involves so many steps and obstacles to reach a mature stage—and then considering the need for a certain amount of water to keep them alive long enough for transport to another viable source—that it’s far less likely to have birds transport them.
Also broached Monday by Aubushon as she presented data taped along a vehicle window in the parking lot, there are 30 known infestations of mussels in California but 28 of those involve the related quagga mussel. The only two known California water sources with zebra mussel infestations, which have wreaked havoc in other areas of the country such as the Great Lakes region and other water sources along the East Coast, are San Justo Reservoir and at the Ridgemark Golf & Country Club property just outside Hollister.
Many of the other California sources infested with quagga mussels remain open to the public under control plans rather than eradication strategies. Most of the Southern California sites use water provided by the Colorado River, which is infested with quagga mussels.
Local officials on several occasions asked about the potential to open the San Justo venue for limited recreation or with the rentals and the possibility of reopening it without a full eradication.
“We would not do that without consulting with the state, Fish & Wildlife and the district,” said Stroup from the bureau of reclamation.
