Lake Sonoma and Lake Mendocino plan for stronger measures to ward off invasive mussels

Lake Sonoma and Lake Mendocino were ringed in recent years by the telltale signs of drought, their diminished water levels leaving exposed earth that in wetter years is well-submerged.

Winter and spring runoff helped to replenish the two reservoirs, which together supply much of the North Bay's drinking water and provide popular destinations to cool off in the summertime.

But a big threat to the two lakes remains in the form of tiny mollusks - quagga and zebra mussels - that are invading fresh water bodies across California and the West, hitching rides from one lake or reservoir to another on boats and trailers.

The bivalve mollusks, imports from Eastern Europe, swiftly colonize large areas, clogging intake pipes, covering docks and damaging other infrastructure while upending aquatic ecosystems.

Their spread, from the Southwest and north from Southern California, has reservoir operators throughout the state on high alert. For several years, Lake Sonoma and Lake Mendocino have been on the front lines of that endless fight, officials say.

“Aside from the drought, the threat of invasive mussels taking hold in either of the two lakes is one of the most significant issues facing our region today,” said state Sen. Mike McGuire, D-Healdsburg, who called the reservoirs “prime targets for infestation,” given their popularity among boaters.

The federal agency that oversees Lakes Sonoma and Mendocino is set to step up its fight against the mussels with mandatory boat inspections slated to begin over the next year.

The program will be supported by $600,000 in state grant funds collected through a statewide, annual $8 boat registration fee. Already, officials are beefing up staff training at the larger Lake Sonoma under a campaign to screen incoming boats for quagga and zebra mussels.

The Sonoma County Water Agency also provides specially trained dogs at the reservoirs on weekends with the ability to sniff out the mature specimens, about the size of a fingernail, as well as the juveniles, called “veligers.” The seasonal program is in its third year.

But officials are eager to implement a more stringent system with mandatory inspections for boats coming to either of the reservoirs after exposure to other bodies of water that may be contaminated. Across California, 33 bodies of water have been infested over the past decade, with the last new discovery made in 2014.

While complex and expensive, officials say an inspection plan is imperative and overdue.

“For three years, we've been working to secure these dollars which will launch a region-wide program to stop these invasive buggers from invading our waterways and we couldn't be more excited to secure this important prevention grant,” McGuire said.

The program likely would include some kind of banding mechanism, such as one used at Lake Tahoe, that would allow boaters only using one of the two reservoirs to avoid the scrutiny applied to vessels that have been launched elsewhere.

The Sonoma County Water Agency, which handles reservoir releases in cooperation with the Army Corps, applied for a two-year grant in 2014, with plans of having an inspection system by early 2015. The application was turned down because the Army Corps is the official reservoir owner and operator, Water Agency spokesman Brad Sherwood said.

In this year's application, the Army Corps was one of 21 recipients given a total of $5 million, according to a spokesman for the state Division of Boating and Waterways.

The two local reservoirs are normally among Northern California's most heavily trafficked lakes, McGuire said, and with water levels up this summer traffic is expected to be high.

“So that's another reason to be concerned and get this thing going,” said Rick Herbert, owner of the newly expanded 360-slip Lake Sonoma Marina.

Quagga and zebra mussels can be transported in ballast water or with live bait, as well as in mud or with aquatic plantlife, but commonly latch onto boats, motors, trailers, axles, wheels and any other exposed surface they encounter, even a tackle box, said Mike Dillabough, district operations and readiness chief with the Army Corps.

They can survive outside of water for five days in warm weather and up to 30 days when it's cold - even longer in freezing weather - making it easy for unsuspecting boaters to introduce them to new waterways.

They reproduce with speed, taking hold in new environments, where they encrust any surface they can find. They are capable of clogging water distribution equipment and lines in a matter of weeks, McGuire said.

A female can produce 5 million eggs in a lifetime, about 100,000 of which reach adulthood, in turn generating more offspring, wildlife experts say.

They are native to Eastern Europe but began turning up in North America around 1989, likely entering through ballast water emptied into the Great Lakes, state Fish and Wildlife officials say.

First discovered west of the Continental Divide in 2007, quagga and zebra mussels have been found in California since that year.

Zebra mussels were found a year later in San Benito County's San Justo Reservoir, a mere three-hour drive from Lake Sonoma, though that's the northernmost infestation so far.

Sherwood said he recently toured San Justo Reservoir, which he called “a prime example as to what we do not want to have happen to our lakes.”

“It's disgusting,” he said. “There are zebra mussel shells covering the shoreline up to like 5 feet.”

Recreational boaters can and do play a critical role in avoiding spread of the mollusks, in part by ensuring their vessels are fully drained, cleaned, dried and sufficiently quarantined before they are introduced into a new body of water.

The payoff is plain and simple: An infested waterway is going to be shut down to boating.

Violators also risk having their boats impounded and fines between $500 and $10,000 if they are found to possess or transport live quagga or zebra mussels.

Boaters “understand the ramifications if (prevention) fails,” and are generally supportive of efforts to avert infestation, said Chris Schooley, district natural resource manager with the Army Corps.

Local efforts also call for installation of motorized gates so public ramps can be locked down when inspectors aren't present. Variables include smaller personal watercraft such as kayaks that don't need such ramps and large sections of uncontrolled shoreline, especially at Lake Mendocino.

A program in place in Lake County since 2008 now includes inspections and $10 stickers giving boaters authorization to launch on Clear Lake. So far, none of the invasive mussels have been found, said Scott De Leon, the county's public works director.

But with nine public boat ramps and more than 700 private ones on Clear Lake, there is no substitute for public education and boater attention to guidelines for draining, cleaning and drying their vessels, he said.

“You don't want to be the person that destroyed the ecosystem and destroyed the fishery and destroyed Clear Lake forever,” he said.

You can reach Staff Writer Mary Callahan at 521-5249 or mary.callahan@pressdemocrat.com. On Twitter @MaryCallahanB.