Invasive Species of Concern

Quagga and Zebra Mussels
Dreissena rostriformis  bugensis
and Dreissena polymorpha

zebra mussels

Zebra Mussels, USFWS photo

quagga mussels

Quagga Mussels
USFWS Photo

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.

In 2008, zebra mussels (Dreissena polymorpha) were found in San Justo Reservoir in central California and have not been observed in any other water body in California, Nevada, nor Oregon.

Quagga mussels (Dreissena rostriformis  bugensis) were first discovered in the Pacific Southwest Region in Lake Mead in January of 2007. Since the initial discovery in Lake Mead, they have been found in many water bodies througout Southern California, southern Nevada, and Arizona.