Quagga Mussel Control Status

dime photoIn December 2013 quagga mussels were detected in Lake Piru. Quagga mussels are an invasive species of mollusks native to central Eurasia which have been gradually spreading across the United States.  Their ability to spread in freshwater aquatic systems and rapidly colonize hard surfaces causes serious economic problems by clogging water intake and conveyance facilities. Since they are also prodigious water filterers, removing substantial amounts of phytoplankton and suspended particulates from the water, quagga mussels are also capable of significantly altering the ecosystem of bodies of water.

Quagga mussels had previously been found in several other locations in Southern California; however, the detection in Lake Piru represents the first instance of quagga mussels in a location which does not receive water from the Colorado River system.

In an effort to learn the scope of the problem, United performed a dive assessment on January 18-19, 2014, during which a more complete survey of the presence of quagga mussles in Lake Piru was compiled.  United is now developing a plan to control this mussel infestation, and further information will be shared through this website as it becomes available. In the interim, United is regularly monitoring the infestation and potential for spread outside of Lake Piru.

Of understandable concern is the potential for movement of quagga mussels into the Santa Clara River system.  Small numbers of mussels have already been detected in lower Piru Creek, immediately below Santa Felcia Dam.  United is required, under its license with the Federal Energy Regulatory Commission for operation of Santa Felicia, to provide a constant release into lower Piru Creek to maintain habitat for endangered Southern California steelhead trout.  These releases, the level of which are triggered by certain hydrologic conditions, range from 7 to 20 cubic feet per second. Under theth the current dry conditions there is not currently a hydrologic connection between Piru Creek and the Santa Clara River, and a substantial amount of rainfall is required for this connection to be re-established.  United will provide more information about the infestation and control measures as it becomes available.

*New Revised Quagga Mussel Monitoring and Control Plan 2019 Annual Report (2020-05-29)

*New Draft Quagga Mussel Monitoring and Control Plan (September 2018)

Santa Clara River Surface Survey for Quagga Mussel

Quagga Mussel Monitoring and Control 2016 Annual Report

Freeman Diversion Facilities Invasive Species Control Options Assessment and Engineering Feasibility Study

Quagga Mussels: An introduction to an aquatic nuisance species

Quagga Activities Update 2016-05-16

Quagga Activities Update 2016-02-23

FERC Letter to UWCD regarding UWCD's efforts to proactively combat Quagga Mussels at Lake Piru

Letter to Calif. Sec. for Natural Resources John Laird in response to concerns raised by Casitas Municipal Water District

Quagga Mussel Fact Sheet

January 8, 2014 Board Mtg. Presentation

UPDATED: 9/18/2017