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The quagga quandary 

Local drinking water supplies are under threat

Miniscule invaders are "musseling in" to California's drinking water supplies, leaving local and state officials scrambling for a solution to stop--or at least slow down--the threat.

click to enlarge MUSSEL HUNT :  Boats visiting Santa Margarita have been inspected for tiny stowaways. Quagga mussels can multiply rapidly, ravage ecosystems, and foul up pumps and pipes. - PHOTO BY STEVE E. MILLER
  • MUSSEL HUNT : Boats visiting Santa Margarita have been inspected for tiny stowaways. Quagga mussels can multiply rapidly, ravage ecosystems, and foul up pumps and pipes.

# Thumbnail-sized quagga mussels and their close allies, zebra mussels, can reproduce by the billions in drinking water reservoirs like Santa Margarita Lake, Lopez Lake, or Nacimiento. Piling up into colonies as much as two or three feet thick, they block water pipes, foul pumps, and clog filters, at the same time stripping lakes of nutrients needed by fish and other aquatic life--and emitting a toxic slime.

Quietly hitchhiking on boats, these tiny creatures have been moving from lake to lake ever since they first arrived in the Great Lakes in the ballast water of ships from the Black and Caspian seas in the Ukraine. Last year, the pests made their way into the Colorado River and the lakes it feeds, and they've recently been discovered living just a few hours' drive from SLO County's drinking water reservoirs--prompting a statewide "incident command" to combat the invasion.


Specially trained mussel- sniffing dogs inspect boats at California's borders. Plankton samples are regularly tested for quagga and zebra mussel larvae. Education of boat owners about the threat is a high priority.

San Luis Obispo officials have been considering protecting Santa Margarita Lake by banning visiting boats, an action taken at Lake Casitas in Ventura County last month. The City Council mulled over their options on April 15, stopping short of a boat ban and instead deciding to urge state and federal agencies to take preventive action.

"It's a scary thing. Trying to keep the mussels out of here is our best bet," said the city's water division manager, Gary Henderson.

Planning an effective response to the invaders is complicated by the overlapping jurisdictions on local lakes, where decision-making authority can be murky. But SLO city and county staffers have been working together to protect Santa Margarita Lake (also known as Salinas Reservoir, one of the main sources of the city's drinking water).

County parks staff jumped into action just in time for a bass fishing tournament that brought visiting boats to Santa Margarita Lake and Lopez Lake April 12 and 13. Starting before sunrise, hundreds of boats were inspected for possible mussel stowaways, then sprayed clean with a powerful hot-water decontamination system before being allowed into the waters.

Even the fishermen's waders were washed down to kill any hidden invaders, according to Ken Klis, supervising ranger at Santa Margarita Lake.

Otto Schmidt lives downstream on the Salinas River and spent weeks lobbying city and county officials to take action to stop the invaders.

"I kept saying, 'You've gotta do something right now.' These mussels would just be catastrophic for the ecosystem. They would wreak havoc on the Salinas River. If they get established here, it's this horrific Pandora's box--there's no putting them back in," Schmidt said.

"It's a very serious threat," explained Mike Hill, reservoir biologist with the California Department of Fish and Game, who met with city and county officials to plan preventive action before the bass-fishing tournament.

"These mussels are very insidious," Hill added.

Adult quagga and zebra mussels can live out of water for 28 days in the right conditions, such as foggy days. Their larvae can live in a puddle on a boat, or in the anchor compartment, or in an engine's cooling water. Their ability to expand is staggering: A single pair can lay up to a million eggs a year, multiplying in five years to "a septillion--that's with 24 zeros," Hill noted.

As filter feeders, they suck up and accumulate heavy metals in their tissue, making them unsafe food for humans or waterfowl. They emit a toxic excrement, known as "pseudo-feces," into the water.

"It's like a slime coat on the bottom of the reservoir. It's just slimy, globby, yucky stuff," said Mark Watson, Fish and Game biologist in the department's Central California office in Fresno.

Central Coast lakes offer just the right conditions for the mussels to thrive, with plenty of calcium for their shells, warm temperatures, and perfect pH.

Biologist Hill is "very concerned" about the threat to Lake Nacimiento, which is controlled by Monterey County and is a planned water supply for San Luis Obispo and the North County. The water intake structure, pipelines, and pumping stations could all be filled up with the troublesome quagga or zebra mussels, creating a very expensive problem.

"We have no specific plan of action designed or in progress," said the deputy director of the Monterey County Water Resources Agency, Bill Phillips, adding that Monterey County officials are currently "trying to collect information."

Mandatory boat inspections and decontamination would be problematic at Lake Nacimiento because of the many private docks on the lake, he said.

"We have a potentially significant problem in Nacimiento in that we have a whole slew of public and private roads with private access to the lake. We have launching places spread around, all over the lake. Where do you put an inspection facility? Highway 101?" Phillips said.

Even banning boats would be difficult because of the two counties involved.

"I don't know if we would have to agree about that. We haven't gotten that far yet. We're learning more about the nature of the problem. We're not asleep at the switch," Phillips added.

New Times contributor Kathy Johnston may be reached at


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