Invasive Species Vs. Your Vessel and Our Waterways— The More You Know.

Identify, address, and prevent California from invasive species invading your vessel and our waterways.

It’s important to be aware of invasive species, which ones are surrounding you, and how to prevent them from ruining your vessel and California waterways. An invasive species is defined as an organism that is not indigenous or native to a particular area. Invasive species can cause significant economic and environmental harm to its new location but can also cause damage to your vessel. However, not all non-native species are invasive. For example, most food crops grown in the United States, including popular wheat, tomatoes, and rice varieties, are not native to the region. A species must adapt to the new area easily to be considered invasive and reproduce quickly. Additionally, it must harm property, the economy, or the native plants and animals of the region.


Non-native aquatic species like plants, quagga mussels (native to Ukraine and Russia), and zebra mussels (native to the Black Sea and the Caspian Sea in Central Asia) invade California’s Sacramento-San Joaquin Delta and reservoirs and lakes. Under the right conditions, these nuisances can multiply at a harmful rate, displacing native species, obstructing waterways, and creating hazardous conditions for navigation and recreation.


Once introduced into a new location, they are almost impossible to eradicate. According to the California Division of Boating and Waterways (DBW), Egeria densa, water hyacinth, and quagga and zebra mussels are some of the nuisance species that can be accidentally transported by recreational boaters when caught in propellers or intakes or attached to hulls. Education on the prevention and removal of these pests is encouraged and will contribute to controlling these aquatic invasive species that are a multi-million-dollar problem in California.


So, as boating season reaches its peak months, what can boaters do to protect their vessels and the waterways they love to visit? Clean, drain, and dry. The California State Parks’ DBW and California Department of Fish and Wildlife (CDFW) are reminding and urging boaters always to remember to clean, drain, and dry their boats before entering and leaving lakes, rivers, and other waterways to help control the spread of quagga or zebra mussels. Invasive plant life can destroy propellers, jam impellers and cause bilge-pump failure. Mussels can attach to boats and negatively affect performance, resulting in engine-cooling components, causing failure, and obstructing water lines, causing system failure and severely damaging the boater’s bank account with high repair costs.


Quagga and zebra mussels are a small species— about one and a half inches long— that attach to hard surfaces, such as boat hulls and pontoons, docks and pilings, rocks, concrete, plastics, and even discarded bottles and cans. According to the California Department of Water Resources, quagga and zebra mussels can be spread to new bodies of water by attaching themselves to boats as adults or as microscopic juveniles in water in motors, bilges, and livewells. They are smaller than a dime, and juvenile mussels can be challenging to see with the naked eye. Their small size does not limit the damage they are capable of. They can cause significant harm to water delivery systems, hydroelectric facilities, and watercraft engines. They also mutate ecosystems and negatively impact recreational activities. In addition, mussels can colonize in watercraft engines or hulls and encrust docks and beaches.


It is recommended for everyone’s benefit that when boating, make it a habit to do the following:

  • Remove all plants and animal material from your boat, trailer, and equipment.
  • Wash your boat’s hull or other watercraft thoroughly, preferably with high-pressure hot water.
  • Clean your gear before entering and leaving the recreation area.
  • Drain the bilge, ballast, wells, and buckets before you leave the area.
  • Inspect all exposed surfaces – small mussels feel like sandpaper to the touch.
  • Dry equipment before launching into another body of water.
  • Allow at least a seven to eight-day dry-out period before entering another body of water.

It is also important to note that in California, it is illegal to import, transport, or possess live or dead quagga or zebra mussels. Boaters must report any mussels found to the local marina and the CDFW hotline at (866) 440-9530 or email: For more information on invasive species laws and regulations, visit CDFW’s website.


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