An invasive mussel first detected in California less than a year ago has surged across the state's southern counties, stirring concern that its spread will inflict costly damage to public water systems and fisheries statewide.
The infamous fresh-water quagga mussel, which has wreaked havoc in the Great Lakes, multiplies so quickly and prolifically that it forms large masses that can clog water pumps, pipelines, power plant intakes and farm irrigation lines.
Its rapid-fire invasion this year from Lake Mead -- which straddles the border between Arizona and Nevada -- southwest to San Diego is alarming water officials in a semi-arid region that heavily depends on imported water moved through a vast network of pipelines and canals.
The quagga already has infested the 242-mile-long California Aqueduct, five San Diego County reservoirs and two of the three largest reservoirs in Riverside County operated by the Metropolitan Water District, which supplies Los Angeles with most of its water.
The mussel's microscopic larvae can swiftly and invisibly move through waterways and the pest is typically found only after it has implanted itself. There is no known method to eradicate the thumbnail sized mussel, but at least one agency is attempting chlorination in the hopes of killing larvae.
Although the quagga does not make water unsafe to drink, officials are concerned that it could infiltrate the State Water Project that delivers water from Northern California to Southern California as well as expansive irrigation systems that feed the state's agricultural industry.
"All of that is subject to disruption by quagga," said Edwin D. Grosholz, an expert on invasive mussels and Cooperative Extension specialist at UC Davis. "There's nothing at all to limit their spread north to Northern California."
He and some other scientists believe that government agencies should be more aggressive in fending off the mussel, especially because of the economic and environmental impacts it could have in Western states.
Water operators are bracing for increased costs.
"If you've got 100,000 of these things clogging up an intake grate, pumps, valves, then you have the time and expense of going in and cleaning it up," said John Liarakos, spokesman for the San Diego County Water Authority.
"It means we will inevitably suffer through higher operation and maintenance costs," said Jim Barrett, director of public utilities in San Diego, where divers must now inspect city reservoirs for mussels.
Experts suspect that the quagga is spreading via water systems and on recreational boats moved by trailer from one marina to another. State agencies have been working since summer to alert and educate boat owners and set up boat checkpoints. The state Department of Fish and Game is even training dogs to sniff out the quagga in corners and crevices of boats and trailers.
"It does represent a very serious threat, and we have to take this very seriously," said Fish and Game Department spokeswoman Alexia Retallack. For instance, the quagga could invade the many lakes and streams that feed the Sacramento-San Joaquin Delta, where the delta smelt and other fish populations are in rapid decline.
"The delta is already a stressed system as is. This could be an additional stresser," Retallack said.
The Los Angeles Department of Water and Power has not found quagga in its system but has begun inspections at its reservoir at Lake Crowley in Mono County, where boating is allowed, said spokesman Joseph Ramallo.
The quagga and its close relative, the zebra mussel, are native to areas around the Caspian and Black seas of Eastern Europe and Asia. The zebra mussel was first found in the United States in 1988 in the Great Lakes, followed by the quagga a year later, probably borne in the ballast water of transatlantic ships.
The quagga had never been identified west of the Continental Divide before its surprise Jan. 6 appearance in Lake Mead, and experts say it likely stowed away west on a boat and trailer to the Colorado River.
The mussel's larvae swiftly moved along the California Aqueduct that carries Colorado River water to Southern California cities. Quagga now is found in Lake Skinner near Temecula and Lake Mathews near Riverside.
To date, however, it has not been found in Diamond Valley Lake near Hemet, the district's newest and largest reservoir, well stocked with bass, trout and catfish to attract fishermen.
"Diamond Valley Lake is now a world-class fishery. We're doing everything we can to make sure the quagga does not become an issue there," said MWD spokesman Bob Muir.
The quagga and zebra mussels have caused an estimated $100 million a year in damages in the eastern United States and Canada, according to a May state report. Mussels can grow in densities of up to 750,000 per square meter in layers more than a foot thick, the report said.