Stockton Fish and Wildlife Office
Pacific Southwest Region
San Justo Reservoir

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Quagga and Zebra Mussels

Quagga mussels were first discovered in the Pacific Southwest Region in Lake Mead in January of 2007. Since the initial discovery in Lake Mead, quagga mussles have been found in many water bodies througout Southern California, southern Nevada, and Arizona . In 2008, zebra mussels were found in San Justo Reservoir in central California and have not been observed in any other water body in California, Nevada, nor Oregon. The U.S. Geolgical Survey maintains an updated quagga and zebra mussel distribution map.

The introduction of quagga and zebra mussels (often referred to as Dreissenids) to the Pacific Southwest Region brings the potential to extend devastating impacts into a geographical area already challenged with water-related problems. Once established, these mussels can clog water intake and delivery pipes, dam intake gates and pipes, adhere to boats, pilings, and most hard and some soft substrates. This impacts water delivery systems, fire protection, and irrigation systems and requires costly removal maintenance.

For more information visit:

Quagga-Zebra Mussel Action Plan for Western U.S. Waters

Calfiornia Deparment of Fish and Game

USGS quagga and zebra mussel information

100th Meridian Initiative





Last updated: March 19, 2012