Natalie Muth, Associated Press
In this photo released by the Utah Division of Wildlife Resources on April 17, 2008, quagga mussels cover a boat's hull. More adult quagga mussels were recently discovered in Lake Powell since water levels have dropped, exposing thousands of aquatic hitchhikers on canyon walls, the Glen Canyon Dam and other areas.
PAGE, Ariz. — The National Park Service and the Utah Division of Wildlife Resources announced Tuesday the discovery of "thousands" of additional adult quagga mussels in Lake Powell.
Since last year, water levels at Lake Powell have dropped, exposing mussels on canyon walls, the Glen Canyon Dam and other areas in the Glen Canyon National Recreation Area.
Boaters have long been required to decontaminate their boats by cleaning, draining and keeping them dry for at least five days before entering the vicinity of another body of water.
"Park staff, partners and the public have worked hard to keep Lake Powell mussel-free for the last 10 years," Glen Canyon Superintendent Todd Brindle said. "It's very disappointing that mussels are in the lake, but most visitors will not notice them. The important thing now is to keep them from being transported to other lakes and rivers."
Quagga mussels and their cousin, zebra mussels, reproduce rapidly and attach themselves to underwater structures, jeopardizing boats, marinas and water intake pipes. The invasive mussels also compete for nutrients with native aquatic wildlife.
If the aquatic hitchhikers become established in Utah, they could cost the state as much as $15 million per year, according to the DWR.
The National Park Service and DWR are developing a plan to manage Glen Canyon's invasive mussels. The public may comment during the plan's development until March 7.
— Morgan Jacobsen