Mussel veligers found in Santa Ana pipeline leading from Silverwood Lake to Lake Perris

By on February 28, 2017
Lake Perris

The California Department of Water Resources (DWR) has confirmed that invasive mussel veligers (the final microscopic larval stage of certain mollusks with two ciliated flaps for swimming and feeding) have been detected in water samples from the North Park valve of the Santa Ana Pipeline. It is unknown at this time whether the veligers are quagga or zebra mussels.

The Santa Ana Pipeline is the water conveyance between Silverwood Lake (San Bernardino County) to Lake Perris (Orange County), spanning some 50 miles. Although extensive sampling has been conducted both upstream and downstream of the North Park valve no mussels have been discovered nor have mussels been detected in either Silverwood Lake or Lake Perris.

As a precautionary measure, the DWR has notified the California State Parks, the United State Forest Service, and State Water Project water contractors affected by this potential detection. A multi-agency response team is collecting additional samples to verify these preliminary results. These efforts are being coordinated with CDFW, the state’s lead agency in invasive mussel management.

At this time, there is no indication of mussels in either Silverwood Lake or Lake Perris. Since 2008, routine monitoring for mussels has been conducted by DWR at both lakes. Further testing is under way by the California Department of Fish and Wildlife to confirm the findings and determine if the veligers are quagga mussels or zebra mussels.

Quagga and zebra mussels are small, non-native freshwater Eurasian mollusks that attach onto hard substrates and can cause damage to water delivery systems. They reproduce prolifically, especially in warm western waters. Despite efforts to control their western expansion, they have begun to rapidly invade California fresh water systems.

The Department of Water Resources (DWR) routinely monitors for mussels and has taken measures to prevent them from infesting the State Water Project (SWP) since the quagga mussel was first discovered in California in 2007. The most recent discoveries of invasive mussels were in December at the Angeles Tunnel, Elderberry Forebay and Pyramid Lake – all of which are located in Los Angeles County.