California agencies combatting the spread of invasive quagga and zebra mussels are reminding boaters to remain cautious over Memorial Day weekend.

Quagga and zebra mussels are invasive freshwater mussels native to Eurasia. They multiply quickly, encrust watercraft and infrastructure, alter water quality and the aquatic food web, and ultimately impact native and sport fish communities. These mussels spread from one body of water to another by attaching to watercraft, equipment and nearly anything that has been in an infested waterbody.

So far none have been found in Lake Tahoe.

Microscopic juveniles, invisible to the naked eye, are spread from infested waterbodies in water entrapped in boat engines, bilges, live-wells and buckets. Quagga mussels have infested 29 reservoirs in Southern California and zebra mussels have infested San Justo Reservoir in San Benito County.

To prevent the spread of these mussels and other aquatic invasive species, people launching vessels at any body of water are subject to watercraft inspections and are strongly encouraged to clean, drain and dry their motorized and non-motorized boats, including personal watercraft, and any equipment that comes into contact with the water before and after recreating.

To ensure watercraft are clean, drained and dry, many local agencies conduct boat inspections, including in the basin and Truckee.

Take the following steps both before traveling to and before leaving a waterbody to prevent spreading invasive mussels, improve your inspection experience and safeguard California waterways:

Clean — inspect exposed surfaces and remove all plants and organisms,
Drain — all water, including water contained in lower outboard units, live-wells and bait buckets, and
Dry — allow the watercraft to thoroughly dry between launches. Watercraft should be kept dry for at least five days in warm weather and up to 30 days in cool weather.