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Invasive Mussel Mitigation
California Department of Water Resources Senior Environmental Scientist Specialist Brianne Sakata, with the Division of Operations and Maintenance, works with California State Parks staff to collect plankton samples to study alongside invasive golden mussels from buoys in O'Neill Forebay in Merced County, California. Photo November 13, 2024.
California Department of Water Resources Senior Environmental Scientist Specialist Brianne Sakata, with the Division of Operations and Maintenance, works with California State Parks staff to collect plankton samples to study alongside invasive golden mussels from buoys in O'Neill Forebay in Merced County, California. Photo November 13, 2024.
Invasive species such as golden, quagga, and zebra mussels can thrive in the California State Water Project as they can survive in a wide range of environmental conditions, posing negative impacts to water delivery systems and the environment. Once these invasive mussel populations are established, they are difficult to control.
Golden mussels were first discovered in North America in October 2024 at the Port of Stockton when DWR discovered the mussels while conducting routine water quality monitoring. The same month, golden mussels were discovered at O’Neill Forebay in Merced County.
Unlike quagga and zebra mussels, the golden mussel (Limnoperna fortunei) can tolerate brackish water and low calcium levels, which means that more waterbodies are vulnerable to infestation. These invasive mussels can:
Alter aquatic ecosystems by filter-feeding on planktonic algae and changing the habitat structure
Impact water delivery systems by clogging small-diameter pipelines, screens, and filters
Impact recreation by fouling boat hulls and motors, and clogging intakes and cooling lines
To prevent these damaging mussels from spreading, DWR routinely monitors for these species and acts to prevent their spread to non-infested waters. DWR partners with agencies such as the California Department of Fish and Wildlife (CDFW) and California State Parks’ Division of Boating and Waterways (DBW) to inform boaters to always remember to clean, drain, and dry their boats before entering and leaving lakes, rivers, and other waterways. DWR also works with partner agencies to routinely sample for adult and juvenile mussels at 18 SWP locations.
Watercraft Inspections at SWP Reservoirs
Watercraft Inspections at Oroville Facilities
Clean, Drain, and Dry
How to Identify Golden, Quagga, and Zebra Mussels