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New Quagga / Zebra Mussel Discoveries in California

Information regarding newly discovered quagga / zebra mussel infestations in California will be posted on this web page. These discoveries are a developing situation; more information will be forthcoming and shared as it is available. Please refer to the Quagga and Zebra Mussel Sightings Distribution in California link opens in new tab or window map (PDF) for the most up-to-date list of confirmed locations.

August 2017 – Santa Clara River

August 30, 2017 - Summary of Discovery

On August 23, 2017, United Water Conservation District (UWCD) notified the California Department of Fish and Wildlife (CDFW) that their staff had surveyed six locations along the Santa Clara River downstream of the confluence of Lower Piru Creek, Ventura County. Their staff discovered one adult quagga mussel on the Torrey Road Bridge, Piru, California, and twelve adult quagga mussels on the 12th Street Bridge, Santa Paula, California. UWCD reported that all quagga mussels detected during the surveys were attached to vertical structures in shaded areas with slow-flowing to still water. UWCD did not discover mussels at any of the other four locations surveyed. UWCD and CDFW have visually identified the specimens as quagga mussels.

CDFW staff surveyed a portion of the Santa Clara River on August 26, 2017. CDFW did not discover mussels at the location surveyed. A plankton sample was collected and sent to CDFW's laboratory for analysis; sample results were negative.

For questions that are specific to UWCD, please contact Anthony Emmert, Deputy General Manager, UWCD, at 805-525-4431. For questions regarding CDFW's response, please contact CDFW's hotline at (866) 440-9530.

February 2017 – Santa Ana Pipeline

February 24, 2017 - News release (Department of Water Resources)

link opens in new windowInvasive Mussel Veligers Detected in the Santa Ana Pipeline; State Conducting Further Testing (PDF)
SACRAMENTO – Mussel veligers (microscopic, free-floating larval life stage) this month were detected in water samples collected at the North Park valve of the Santa Ana Pipeline, which transports water from Silverwood Lake, San Bernardino County, to Lake Perris, Riverside County. Further testing is under way by the California Department of Fish and Wildlife (CDFW) to confirm the findings and determine if the veligers are quagga mussels or zebra mussels...

December 2016 – Pyramid Lake, Angeles Tunnel, Castaic Power Plant, Elderberry Forebay, Castaic Lake, Castaic Lagoon

August 30, 2017 - Updated Information Regarding Discovery

On December 13, 2016, Department of Water Resources (DWR) and Metropolitan Water District of Southern California (MWD) staff inspected the Angeles Tunnel again and ten additional dead quagga mussels were detected. The mussels range from 13-33 mm, similar in size to the six mussels initially discovered on December 8. Staff also inspected the drainage water in the Pyramid Dam stream release access chamber and in Middle Piru Creek immediately below the dam; no mussels were detected.On December 14, 2016, DWR and MWD staff collected plankton tow samples on Pyramid and Castaic Lakes. Samples were sent to Scripps and MWD laboratories for analysis; sample results were all negative. At Pyramid Lake, staff also inspected spillway buoys, outlet tower buoys, settlement plates, and two Sherriff boats that were pulled from the water; no mussels were detected. At Castaic Lake, settlement plates and rocky shoreline near the inlet were inspected; no mussels were detected. The Los Angeles County Department of Parks and Recreation divers dove in Castaic Lake and inspected hard substrates such as buoys and anchor cables; no mussels were detected.

On December 20, 2016, remote operated vehicle (ROV) inspection of Pyramid Angeles Tunnel intake was inspected to a depth of approximately 300 feet. One mussel was observed and appeared to be alive.

On January 4, 2017, MWD inspected their Foothill Hydro Electric Plant just downstream of Castaic Lake. The plant has several strainers and filters that were removed, and their contents returned to the lab for inspection; no mussels were detected.

All subsequent sampling conducted to date has been negative.

On December 14, 2017 (not December 15, 2017 as previous reported), MWD and Los Angeles Department of Water and Power (LADWP) inspected the dewatered Elderberry Forebay  . Two adult quagga mussels were discovered at the Castaic Power Plant at the northern end of Elderberry Forebay.  Laboratory analysis conducted by MWD corroborated the visual species identification. MWD inspected the dewatered outlet tower and dam of the Elderberry Forebay; no mussels were detected.

December 16, 2016 - Summary of Discovery

On December 8, 2016, six adult quagga mussels were discovered by California Department of Water Resources (DWR) in the Angeles Tunnel, a pipeline that moves water from Pyramid Lake to Elderberry Forebay and subsequently Castaic Lake (Los Angeles County). Laboratory analysis conducted by CDFW corroborated the visual species identification made by DWR staff. Based on this discovery the California Department of Fish and Wildlife (CDFW) considers Pyramid Lake to be infested with quagga mussels.

On December 15, 2016, Metropolitan Water District of Southern California and Los Angeles Department of Water and Power (LADWP) discovered two adult quagga mussels at the Castaic Power Plant at the northern end of Elderberry Forebay, which is currently dewatered. Specimens have been sent for laboratory analysis to corroborate the visual species identification.

Given the connectivity of the waterbodies, CDFW presumes that Castaic Lake and Castaic Lagoon have been exposed to mussels and warrant management actions be taken comparable to those where adult mussels have been found.

DWR, the manager of Pyramid and Castaic lakes, and LADWP, manager of Castaic Power Plant and Elderberry Forebay, are implementing actions to contain the infestation and managing exiting watercraft to prevent the movement of quagga mussels and infested water. DWR and local agencies are conducting additional surveying to determine the extent of the infestation. CDFW will continue to work with DWR and LADWP to delineate the infestation and develop a control plans for the infested waterbodies.

Boaters at these waterbodies, as well as all other waterbodies, should continue to clean, drain, and dry their watercraft and equipment after every visit. Waterbodies with prevention programs screening for high-risk watercraft should consider Pyramid Lake, Elderberry Forebay, Castaic Lake, and Castaic Lagoon infested waters and manage watercraft originating from these waterbodies accordingly.

For questions that are specific to DWR’s response, please contact Doug Carlson, DWR Information Officer, (916) 653-5114 or Ted Thomas, DWR Information Officer, (916) 653-9712. For questions regarding CDFW’s response, please contact CDFW’s hotline at (866) 440-9530.

December 15, 2016 - News release (Department of Water Resources)

link opens in new tab or windowQuagga Mussel Infestation Triggers Boating Restrictions at Pyramid and Castaic Lakes SACRAMENTO – Boats leaving Pyramid Lake and Castaic Lake are subject to restrictions to help prevent the spread of quagga mussels, which were discovered last week in a tunnel that connects the two Los Angeles County lakes, the California Department of Water Resources (DWR) announced today...

December 9, 2016 - News release (Department of Water Resources)

link opens in new tab or windowQuagga Mussel Infestation Discovered in Pyramid Lake; State Imposes Boating Restrictions SACRAMENTO – The Quagga Mussel is a small, non-native freshwater mollusk that the Department of Water Resources (DWR) had successfully prevented from infesting the State Water Project (SWP) since the species was first discovered in California in 2007. However, on December 8, six adult quagga mussels were found in the Angeles Tunnel, which serves as a connector between Pyramid Lake and Elderberry Forebay, two SWP components north of Los Angeles...



Habitat Conservation Planning Branch
1416 Ninth Street, 12th Floor, Sacramento, CA 95814
(916) 653-4875