Boaters Asked to Help Fight Spread of Invasive Quagga and Zebra Mussels Over Labor Day Weekend

Media Contacts:
Vicky Waters, California State Parks Division of Boating and Waterways, (916) 653-5115
Kyle Orr, California Department of Fish and Wildlife, (916) 322-8958
Christina Jimenez, California Department of Water Resources, (916) 653-0979
Steve Lyle, California Department of Food and Agriculture, (916) 654-0462

California agencies combating the spread of invasive quagga and zebra mussels remind boaters to remain alert over the three-day Labor Day weekend.

Quagga on quarter

People who launch vessels at any body of water are subject to watercraft inspections and are 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 at a waterway.

“Californians have a unique opportunity to enjoy numerous natural resources,” said California Department of Fish and Wildlife (CDFW) Director Charlton H. Bonham. “Doing your part to clean, drain and dry before heading out to recreate will help keep them free of quagga and zebra mussels, as well as other invasive species.”

Quagga and zebra mussels, non-native freshwater mussels native to Eurasia, multiply quickly and encrust watercraft and infrastructure, and compete for food with native and sport fish species. These mussels can be spread from one body of water to another by nearly anything that has been in an infested waterbody, or via standing water from an infested waterbody entrapped in boat engines, bilges, live-wells and buckets.

To ensure that watercraft are clean, drained and dry, many local agencies are conducting boat inspections. CDFW has posted a list of these inspections on its website ( along with additional information about the invasive mussels and what people can do to help prevent their spread in California. Boaters should call ahead to check for restrictions prior to visiting their destination.

To prevent spreading invasive mussels and to breeze through an inspection, boaters can take a few simple steps before arriving at a water body. These include inspecting all exposed surfaces, removing all plants and organisms, draining all water, including water contained in lower outboard units, live-wells and bait buckets, and allowing 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. These measures are essential to safeguard California waterways.

CDFW has developed a brief video demonstrating the ease of implementing the clean, drain and dry prevention method, which can be viewed at In addition, a detailed guide to cleaning vessels of invasive mussels is available on the California State Parks Division of Boating and Waterways (DBW) website at

Travelers are also advised to be prepared for inspections at California Department of Food and Agriculture Border Protection Stations. Inspections, which can also be conducted by CDFW and the Department of Parks and Recreation, include a check of boats and personal watercraft, as well as trailers and all onboard items. Contaminated vessels and equipment are subject to quarantine or impoundment.

Quagga mussels were first detected in the Colorado River system in January 2007 and were later found in San Diego and Riverside counties. They are now known to be in 29 waters in California, all in Southern California. Zebra mussels were discovered in San Justo Reservoir in San Benito County in January 2008.

Both species can attach to and damage virtually any submerged surface. They can:

  • Ruin a boat engine by blocking the cooling system and causing it to overheat
  • Jam a boat’s steering equipment, putting occupants and others at risk
  • Require frequent scraping and repainting of boat hulls
  • Colonize all underwater substrates such as boat ramps, docks, lines and other underwater surfaces, causing them to require constant cleaning
  • Cost the owners of these items a lot of money

A multi-agency effort that includes CDFW, DBW, the Department of Water Resources, and the Department of Food and Agriculture has been leading an outreach campaign to alert the public to the quagga and zebra mussel threats. A toll-free hotline at 1-866-440-9530 is available for those seeking information on quagga or zebra mussels.