The invasive quagga mussel (Dreissena rostiformis bugensis) was found in Lake Mead in January of 2007. Quagga mussels were likely transported to Lake Mead attached to the hull of a recreational vessel which had traveled from the Great Lakes area. Since being introduced to Lake Mead, quagga mussels have spread to Lake Mohave and have reproduced rapidly in both lakes.
Quagga mussels pose significant threats to infrastructure, recreation, and ecosystems in lakes Mead and Mohave. Adult mussels colonize water intakes, marina structures, and navigation aids requiring expensive defouling and repair. Shells of dead mussels are hazardous to people on beaches, and larval mussels, called veligers, are drawn into boat engines and bilges where they grow into adults and clog recreational equipment. Mussels feed by continuously filtering water for plankton, and the tremendous filtering capacity of large colonies of mussels can deprive other aquatic species of resources necessary for survival, causing irreversible ecosystem changes and losses of both native species and sport fisheries.