Since first confirmed in Lake Powell three years ago, quagga mussels are now present in nearly all parts of the massive lake on the Arizona-Utah line.
A Glen Canyon National Recreation Area update also says that larvae have been found in the Colorado River below Glen Canyon Dam.
Officials say mussels have been found attached to moored boats and structure, on the lake’s bottom and attached to canyon walls.
Quagga mussels are an invasive species. They can ruin boat motors and clog water intakes.
Larvae were first confirmed in Lake Powell in late 2012 through routine tests of water samples taken from near the dam and Antelope Point. Adult mussels were first reported in March 2013 when a boat services business found some on a boat awaiting service.