Lake County supervisors are again asking voters to help them keep invasive, ecology-altering mussels out of Clear Lake.

"It's ultimately up to voters," said Supervisor Tony Farrington.

Supervisors on Tuesday unanimously approved placing a half-percent sales tax increase on the June ballot.

The "Healthy Lake Sales Tax" would boost funding for the county's battle against quagga and zebra mussels. It also would fund clean water and wetlands projects and the ongoing battle to control the chronic overgrowth of aquatic plants in the lake.

A similar ballot measure was narrowly defeated in 2012, but its proponents had just two months to campaign for the measure, Farrington said. He's hoping the extra two months this time around will bring success.

The ballot measure would increase the sales tax in the unincorporated county from 7.5 percent to 8 percent, he said. It would raise an estimated $2.4 million annually for the water-related projects.

The county currently spends between $300,000 and $500,000 a year on mussel prevention and weed control, much of it from one-time funding.

"We can't continue to be shelling out money every year without revenue coming in," said Supervisor Rob Brown.

A large chunk -#8212; $1 million -#8212; of the new tax dollars would go toward keeping tiny but potentially devastating quagga and zebra mussels out of Clear Lake.

The Eastern European invaders have been steadily making their way across the country since being introduced to the Great Lakes in the 1980s.

They have hitchhiked their way across country, primarily on and in watercraft, wreaking havoc on lakes and streams and clogging drinking-water systems.

If they invade Clear Lake, they would alter the lake's ecosystem, eventually causing the collapse of its fish and bird populations, said Lake County Water Resource Director Scott DeLeon.

Clear Lake is the county's main tourist draw and its demise would be devastating to the county's already weak economy.

The invasive mussels so far have made their way to Southern California and Nevada. In December, they were found in Lake Piru, in Ventura County.

State and federal officials have offered little help to Lake County fight the pest, leaving local officials largely on their own, supervisors said.

"It's ridiculous for them to consider this a local issue," Brown said.

If the mussels get into Clear Lake, they would then spread, via Cache Creek, to Yolo County. From there, they could make it to the San Joaquin Delta, DeLeon said.

If they're introduced into Lake Pillsbury, the mussels could migrate into the Eel and Russian rivers, he said.

"An infestation in Clear Lake and its surrounding lakes could have a huge impact on Northern California," DeLeon said.

State officials said they're very concerned but have limited financial resources to pass on to counties. But later this year, counties will be able to apply for grants through a newly established fund managed by the California Department of Boats and Waterways, said Susan Ellis, environmental program manager for the Invasive Species and Rare Plant Protection Programs for the California Department of Fish - Game.

The grants will be funded through an $8 dollar fee imposed on inland boat owners, she said.

Currently, food and agricultural inspectors at state borders do check for mussels. They inspected 82,000 boats last year and stopped 116 contaminated boats from entering California, Ellis said . One of those boats was headed to Lakeport, she said.

It's up to counties to inspect boats traveling within the state.

Lake County several years ago initiated a mussel inspection, boat cleaning and sticker program for Clear Lake, but it's inadequate, officials said. The program is funded largely by sticker sales, which generate about $45,000 annually.

If voters approve the new tax, Farrington said the county will set up 24 hour inspection stations at entry points to the county, much like a mussel-prevention program in Lake Tahoe.

Because the proposed tax would have specific uses, it will require approval by 66.7 percent of voters. The 2012 ballot measure received 63 percent of the vote.

You can reach Staff Writer Glenda Anderson at 462-6473 or glenda.anderson@pressdemocrat.com.