Take steps to stop highly invasive species

Image of mussels
Quagga and Zebra mussels are harmful, highly invasive freshwater species recently discovered in California waters. California’s resources agencies have stated that the further spread of Quagga or Zebra mussels in California waters may result in an environmental and economic disaster. Learn more about the mussel invasion. Visit Quagga and Zebra Mussels Incident Description.

Current infestations in California are limited to Quagga in several Southern California reservoirs that receive water from the Colorado River. There is one Zebra mussel infestation at an isolated reservoir in San Benito County. Access the map. Visit Zebra and Quagga Mussel Sightings Distribution.

The appearance of the mussels has heightened concern that they may infest other California waterways.

Recent California legislation added a requirement to the California Fish and Game Code. Owners and managers of reservoirs must assess the vulnerability of their reservoirs for the introduction of nonnative dreissenid mussel species, such as Quagga and Zebra. They must develop and implement a program designed to prevent the introduction of these mussel species.


Learn about the potential environmental impact

In waters outside their native range, Quagga and Zebra mussels are harmful, highly invasive freshwater species. Favorable growing conditions and the absence of natural predators contribute to their rapid colonization and expansion. Quagga and Zebra mussels can have significant negative impacts on the natural environment, including:

  • Disruption of aquatic food chains
  • Disruption of ecological communities
  • Displacement of native aquatic species


Learn about the potential effect on recreational activities

PG&E operates many lakes and reservoirs for public recreation and producing clean, renewable hydroelectricity. The effects on personal and public property infested with Quagga and Zebra mussels can include:

  • Impacted recreational activities, including sport fishing
  • Beaches littered with sharp shells
  • A foul odor as the mussels decompose
  • Fouled boats, docks, ramps and other marina facilities
  • Damaged boat engines and steering components

Get more information about public recreational facilities. Visit Another benefit of Hydropower.


Learn about the potential impact on PG&E facilities and operations

To protect our assets and the ecological integrity of the waters we manage, and to comply with AB 2065, we began implementing an infestation prevention program for our reservoirs and waterways in 2009. The program includes public education, monitoring and management of permitted recreational, boating and fishing activities. We work with local, state and federal agencies, other utilities and recreational facility operators to ensure that the program is effective. The program includes the following elements to help prevent the infestation of Quagga and Zebra mussels:

  • A vulnerability assessment of PG&E lakes and reservoirs to determine the potential for mussel infestation
  • A public education program to inform reservoir users of the infestation risk and measures to prevent an infestation
  • Monitoring for early detection of the mussels
  • Management of recreational, boating and fishing activities (as needed)


Learn the California Department of Fish and Game boat inspection guidelines

Quagga and Zebra mussels can clog water pipes, coat piers and ruin boat motors. Transferring a boat from an infested body of water to another may spread the mussels. Boaters must check their boats, trailers and vehicles each time they take the boat out of a lake or reservoir.


When leaving the water:

  • Inspect all exposed surfaces. Small mussels feel like sandpaper to the touch.
  • Wash the hull of each watercraft thoroughly.
  • Remove all plant 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 all buckets.
  • Dispose of all bait in the trash.
  • Allow the vessel to dry for five days in hot weather and up to 30 days when cool and moist. Keep watercraft dry between launches in different bodies of freshwater.

Boat Inspection Guidelines Image



Contact us

Report sightings of Quagga and Zebra mussels by calling the California Department of Fish and Game Quagga and Zebra Mussel Hotline: 1-866-440-9530.

Get more information about helping to prevent the invasion. Visit California Department of Fish and Wildlife Quagga and Zebra Mussels.

We appreciate your vigilance and support to keep California’s waters free of invasive mussels.