DFG News Release

Zebra Mussels Found in California Reservoir

Zebra mussels have been found in the San Justo Reservoir in San Benito County, the Department of Fish and Game (DFG) confirmed today. This is the first population of this destructive invasive species to be found in California waters.

"The discovery of Zebra mussels in a central California waterway has us very concerned," said Secretary for Resources Mike Chrisman. "Like its relative the Quagga mussel, this species can cause significant environmental, recreational and economic impacts once established in a body of water. It is important that boaters do everything they can to help stop their spread."

An angler fishing in the San Justo Reservoir last week reported landing a clump of what appeared to be mussels. These mussels and a sample collected by DFG biologists were then verified to be Zebra mussels by the California Department of Food and Agriculture (CDFA) laboratory. Similarly, Quagga mussels were first detected in the Colorado River system in January 2007 and were later found in San Diego and Riverside counties by state and local water agencies.

A multi-agency taskforce that includes DFG, Department of Water Resources (DWR), the Department of Boating and Waterways and California State Parks has responded with surface and underwater inspectors to determine the extent of the threat to California waters from Zebra and Quagga mussels.

No mussels have been detected on artificial substrates in the San Luis Reservoir, which flows into the San Justo Reservoir, or in the O’Neill Forebay. So far, mussels have not been found anywhere in California's State Water Project (SWP), which draws its water from Northern California watersheds. DWR regularly monitors for Zebra and Quagga mussels throughout the SWP, one of the largest water and power systems in the United States.

Both species of mussel are non-native aquatic mollusks that wreak havoc with the environment by disrupting the natural food chain and releasing toxins that affect other aquatic species. Although they range in size from microscopic to the size of a fingernail, they are prolific and attach themselves to hard and soft surfaces. Boats are the primary transporters of Zebra and Quagga mussels. The Zebra mussels inhabit water depths from 4 to 180 feet, with Quagga reaching depths more than 400 feet, and can attach to and damage boat trailers, cooling systems, boat hulls and steering equipment. Mussels attached to watercraft or trailers can be transported and spread to other water bodies. Water in boat engines, bilges, live wells and buckets can carry mussel larvae (veligers) to other water bodies as well. A mussel infestation can potentially lead to the closure of boating in affected waterways. San Benito County Public Works closed San Justo Reservoir to all boating activity.

The main risk of mussel introduction into the SWP is from trailered boats. It is important to follow the steps listed below and to cooperate with vessel inspections that are being conducted at a number of CDFA border inspection stations around the state to help prevent the spread of Zebra or Quagga mussels to any water system.

All boaters and anyone who accesses freshwater aquatic environments should take the following steps to inhibit the spread of mussels when leaving the water:

• Inspect all exposed surfaces - small mussels feel like sandpaper to the touch
• Wash the hull of each watercraft thoroughly, preferably with high pressure/hot water
• Remove all plants and animal material
• Drain all water and dry all areas
• Drain and dry the lower outboard unit
• Clean and dry all live-wells
• Empty and dry any buckets
• Dispose of all bait in the trash
• Wait five days and keep watercraft dry between launches into different fresh waters

A toll-free phone line, 1-866-440-9530, has also been established for anyone involved with activities on lakes and rivers seeking information about Zebra or Quagga mussels. This public line is staffed Monday through Friday, 8 a.m. to 5 p.m.

DFG is also conducting trainings around the state about how to inspect boats for Zebra and Quagga mussels. The trainings are open to water managers, marina operators and other local, county and state officials. The next trainings are scheduled in Sacramento on Jan. 23, and Fresno on Jan. 24. To register for either class, officials should call (916) 928-8330 as soon as possible to ensure a seat. There is no charge for attending the class.

For more information on Zebra and Quagga mussels, visit the DFG Web site at www.dfg.ca.gov/invasives/quaggamussel.