Quagga Mussel Discovery at Castaic Lake: Boating Requirements Implemented


image of large quagga mussel

Image of large quagga shell.

SACRAMENTO, Calif. The California Department of Water Resources (DWR) will begin implementing additional boating requirements at Castaic Lake in Los Angeles County due to the recent discovery of invasive quagga mussels.


The discovery of quagga mussels means DWR must implement measures to prevent their spread, including requiring boats to be inspected and drained upon leaving Castaic Lake and Castaic Lagoon. While mussels have not been detected to date in Castaic Lagoon, they are presumed to be present since the lagoon receives water from Castaic Lake.


DWR and California Department of Fish and Wildlife (CDFW) staff discovered two quagga mussel shells on August 17, 2021, at Castaic Lake. Earlier in the month, a park visitor reported finding a live mussel in the lake. DWR and CDFW have not detected larval “veliger” stage mussels in Castaic Lake during routine monitoring. CDFW and DWR plan to continue monitoring Castaic Lake and Lagoon, and plan to increase monitoring in the Lagoon and Castaic Creek.


Quagga mussels, which are small, non-native freshwater mollusks, were first discovered in the Colorado River and in California in 2007. In 2016, they were found in Pyramid Lake, the Angeles Tunnel, and Elderberry Forebay. The mussels can be a threat to California’s native species and can clog water systems, colonize hard surfaces, alter food webs in ecosystems, and damage boat engines.


Boats are required to be inspected by the Los Angeles County Department of Parks and Recreation before leaving Castaic Lake and all water must be drained from outboards, bilges, live-wells, ballast tanks, bait buckets and any other areas containing lake water. Boats must still pass an entrance inspection and be clean, drained, and dry to be allowed to launch. Entrance inspections are still required because they prevent additional invasive species introductions.


Boats departing Castaic Lake will receive a tag indicating they were last used in a waterbody containing mussels. Tags will allow entry of boats at Pyramid and Castaic lakes without having to be reinspected since both lakes are classified as infested with quagga mussels. After boating in an infested lake, boat owners may experience restrictions or extended dry out periods before visiting another waterbody. Boaters are advised to contact the waterbody destination to be informed of any inspection requirements before their arrival.


Transportation or possession of live or dead quagga mussels, including water that may contain their microscopic larvae, is a violation of Fish and Game Code 2301 and CDFW has authority to take enforcement action.


For additional boat cleaning guidelines, go to A Guide to Cleaning Boats (ca.gov) or DWR’s Quagga Mussels: Clean, Drain, and Dry video.


Maggie Macias, Information Officer, Public Affairs, Department of Water Resources

(916) 820-7662 | maggie.macias@water.ca.gov