Quagga and Zebra Mussels

Incident Description

Quagga mussels were discovered in Lake Mead in Nevada on January 6, 2007, and later throughout Lake Mead’s lower basin. It was the first discovery of either of these mussels west of the Continental Divide. Subsequent surveys found smaller numbers of Quagga mussels in Lakes Mohave and Havasu in the Colorado River, and in the Colorado River Aqueduct System which serves Southern California. Surveys in August found Quagga in Lake Dixon and San Vicente Reservoir in San Diego County. All reservoirs, lakes and watersheds receiving raw Colorado River water have been exposed to Quagga mussels. The first confirmed find of Zebra mussels in California occurred at San Justo Reservoir January 10, 2008. [MORE]


Dreissenid Mussel Prevention Program Development and Requirements

Fish and Game Code §2302(opens in new tab) requires that any person, agency, district, or authority that owns or manages a reservoir that is open for public recreation and not infested with dreissenid mussels (e.g. quagga and zebra mussels) must 1) assess the vulnerability of the reservoir to introduction of dreissenid mussels, and 2) develop and implement a program to prevent the introduction of dreissenid mussels. Prevention programs are required to include public education, monitoring for the presence of both adult and veliger dreissenid mussels, and management of recreational activities.

  • It is a violation of Fish and Game Code and the California Code of Regulations Title 14 (14 CCR) §672.1(opens in new tab) for water owners/managers to operate a reservoir, as qualified by FGC §2302, without developing and implementing a prevention program that meets the requirements defined in 14 CCR §672.1 (b).
  • Water owners/managers are required to submit to CDFW a written document describing the prevention program being implemented and demonstrating its compliance with 14 CCR §672.1.
  • Prevention programs should be developed, implemented, documented, and the written document submitted to CDFW without delay.
  • If a reservoir’s prevention program has not yet been received by CDFW, the Department will issue a notification requesting documentation of the prevention program, after which water owners/managers will have 90 business days to submit the required written document demonstrating implementation of the program and compliance with the laws and regulations.
  • Subsequently, prevention program implementation shall be demonstrated through submission of an annual report (Jan 1 – Dec 31) to CDFW by March 31 of each year. Annual reports must summarize any changes in the reservoir’s vulnerability, monitoring results, and management activities.
  • Under 14 CCR §672.1, any person, agency, district, or authority that fails to submit a prevention program, revision, or annual report, meet the regulatory deadlines for submissions, or report a discovery of dreissenid mussels, live or dead, is subject to an administrative penalty of up to $1000 per offense.

To facilitate compliance with the applicable laws and regulations, CDFW has developed guidance, below, for the development and documentation of dreissenid mussel prevention programs, including suggestions for assessing reservoir vulnerability, conducting effective monitoring activities, and preparing the written program document and annual reports. Water owners and/or managers are encouraged to work directly with their respective CDFW regional quagga/zebra mussel scientist (PDF)(opens in new tab) to adequately assess the vulnerability of their reservoir(s) and develop a prevention program that is both effective and compliant with the applicable laws and regulations. Questions or requests for assistance may be directed to respective regional scientists or the Invasive Species Program at invasives@wildlife.ca.gov.


Outreach and Education Materials

To order printed Rack Cards and Posters, email invasives@wildlife.ca.gov for an initial supply. CDFW will provide an electronic file for reproducing additional copies.

CDFW Invasive Species Program
P.O. Box 944209, Sacramento CA 94244-2090

Fisheries Branch
1010 Riverside Parkway, West Sacramento, CA 95605 | Fisheries@wildlife.ca.gov