The recent spread of dreissenid mussels to various bodies of water in the western US has sparked interest by many state and federal agencies to develop protocols to stop further expansion. Quagga mussels (Dreissena rostriformis bugensis) are of particular importance as they are currently the most widespread dreissenid species in the region. This project examined the susceptibility of quagga mussels to hot-water sprays at different temperatures and durations of spray contact at Lake Mead (Nevada-Arizona, USA). Emersed adult quagga mussels were exposed to hot-water sprays at 20, 40, 50, 54, 60, 70, and 80°C for 1, 2, 5, 10, 20, 40, 80, and 160 s. Sprays at ≥60°C for 5 s were shown to be 100% lethal. Sprays of 54°C for 10 s, 50°C for 20 s, and 40°C for 40 s also resulted in 100% mortality. A spray temperature of 60°C for 5 s is recommended for mitigating fouling by quagga mussels.