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Southern Nevada Water Authority

Quagga Mussels


Quagga mussels. Photo courtesy of the
U.S. Fish and Wildlife Service.

Discovered in January 2007 at Lake Mead, non-native quagga mussels have caused quite a stir in Southern Nevada. Similar to its cousin, the zebra mussel, the quagga mussel is described by scientists as one of the most invasive species worldwide and can live at depths of nearly 400 feet.

Sometimes referred to as "biological pollution," species like the quagga mussel can cause irreversible harm to the environment. Quaggas pose a serious threat to the ecosystem as well as the water intake system located at Lake Mead.

Quaggas filter up to a liter of water per day, impacting the food chain of native fish and other aquatic wildlife by decreasing the food supply. They also clog and restrict water flow in pipes of all sizes, requiring costly upkeep and repairs. To make matters worse, they multiply at an alarming rate. A single female quagga can produce more than one million eggs in a spawning season.

Quaggas in Lake Mead

Initially discovered in Boulder Basin in early 2007, the mussels have subsequently been found throughout Lake Mead both as adult mussels and as juveniles.

The Southern Nevada Water Authority (SNWA), in cooperation with the Lake Mead National Recreations Area, UNLV, UNR, and other agencies have developed an Interagency Monitoring Action Plan to coordinate the collection and sharing of quagga mussel data for Lake Mead.

SNWA contributes to this effort through our routine Lake Mead water quality sampling program, the collection of juvenile mussels during our water quality sampling, and the regular inspection of our drinking water intake structures by divers.

Other agency partners provide additional water quality data and juvenile mussel data throughout the lake, information on colonization by adult mussels, evaluations of the impact on other organisms, and assistance in preventing the spread of mussels by boats leaving the lake.

No live adult quaggas have been found at SNWA treatment facilities and improvements are being implemented to prevent the colonization of the intake structures by mussels. These control technologies have been incorporated into the design of the third intake that is currently under construction.

Veligers (quagga larvae) have been found in the raw water as it comes into the treatment plants, but it should be noted that SNWA's water treatment processes destroy all quagga before they can get into the drinking water system.


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