Quagga/Zebra Mussels

Quagga & Zebra Mussel
Keep these invasive species out of Nevada County
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 of 2007, 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.                         
Origin:  Zebra mussels arrived in North America from Europe in the 1980s followed shortly thereafter by their close relative the Quagga mussel.  They are among the most devastating invasive species to invade North American fresh waters and have spread to many water bodies in the eastern and Midwestern United States and have now been found in several of the western states.  The arrival of quagga and zebra mussels in a region creates severe ecological and economic impacts. As prodigious water filterers, they remove substantial amounts of phytoplankton, zooplankton and suspended particulate from the water, which reduces the food sources for zooplankton and small fish, altering the food web. With the filtering out of suspended particulates and phytoplankton, water clarity increases allowing sunlight to penetrate the water deeper triggering increased vegetation growth that can affect oxygen levels resulting in fish die offs.
Damage:  Once established, these mussels can clog water intake and delivery pipes, infest hydro power infrastructure, adhere to boats and pilings, foul recreational beaches and damage and forever change fisheries.  Over eighty percent (80%) of the water used by farms, businesses, and the 38 million strong population of California originates in rural northern California counties making preventing the infestation of these headwaters of paramount importance.  
The primary methods of advance between water systems are by water flow (connected waterways) and trailered watercraft (non-connected waterways) and that advance has not been stopped by present methods, only slowed.  
Quagga/Zebra mussels accumulate organic pollutants within their tissues to levels more than 300,000 times greater than typical concentrations in the environment.  The mussels’ wastes significantly lower the oxygen levels, lowering the pH to an acidic level and generating toxic byproducts. The mussels have also been associated with outbreaks of botulism poisoning in wild birds.
Zebra mussels heavily colonize hard substrates while the Quagga colonize both hard and soft substrates. It appears as though the Quagga colonize deeper thanZebra mussels, infesting a wider range of habitats.  In locations where both mussels exist, the Quagga mussel appears to compete with the Zebra mussel, eventually replacing it. Quagga/Zebra mussels clog water intake structures, such as pipelines and screens, reducing pumping capabilities for power and water treatment facilities.  Recreation-based industries and activities are also affected by the mussels which take up residence on docks, break walls, buoys, boats and beaches. For boaters, Quagga/Zebra mussels increase drag, clog engines causing overheating and can affect steerage. 
Although these mussels are making inexorable progress into the water bodies of California, there is still the opportunity to prevent significant damage if coordinated and extensive action is taken immediately. Without increased and immediate action, these mussels will cause irreparable ecological and economic damage to California water bodies and long-term costs could be in the billions.
Information from:
Nevada County Agricultural Commissioner
California Department of Fish and Game
US Geological Survey
Progression of Quagga and Zebra Mussel in the US (map):
Quagga & Zebra Mussel Flyer and Brochure:
Additional Information: