Quagga mussel larvae, or veligers, were first confirmed in Lake Powell in late 2012 after routine water monitoring tests discovered mussel DNA in water samples taken from the vicinity of Antelope Point and the Glen Canyon Dam. As of early 2016, thousands of adult quagga mussels have been found in Lake Powell, attached to canyon walls, the Glen Canyon Dam, boats, and other underwater structures, especially in the southern portions of the lake. It is crucial to keep the mussels from moving from Lake Powell to other lakes and rivers. Utah and Arizona state laws require you to clean, drain, and dry your boat when leaving Lake Powell using self-decontamination procedures.