GRAND LAKE — As boaters ramp up for the season, they must also remain vigilant about aquatic stowaways.

The Colorado Parks and Wildlife released an updated list of watercraft inspection and decontamination sites last Friday. In Grand Lake, Shadow Mountain Reservoir and Granby Reservoir, Parks and Wildlife tests have detected Quagga mussel larvae, but no adults have been detected as of yet. Zebra mussel larvae have been found in Grand Lake as well.

All boats must be inspected prior to entering and exiting these water bodies. Inspectors will issue green seals after exit inspections, which are accepted at other state-authorized inspection site, and help expedite the launching process.

Mussel larvae have also been detected in Willow Creek Reservoir, which is closed to motorized, trailer-launched watercraft for the 2013 season.

“We don’t have an infestation to date,” said Mike Porras, regional public information officer for Colorado Parks and Wildlife. “We’re asking for the public’s cooperating in keeping them from spreading.”

No adult mussels have been found in Grand County’s waters.

The mussels are an invasive species that filter microscopic organisms from the water, which alter water body ecosystems and destroy food sources for fish. They can also clog engines and ruin equipment. Originally native to the freshwater streams and rivers of Russia and the Ukraine, the mussels came to North America through ballast water discharged by ships on transoceanic voyages. Overland transport of boats between water bodies has allowed mussel larvae to spread throughout the continent. To prevent further mussels spread, Parks and Wildlife encourage boat owners to drain watercraft of water, clean watercraft and any other equipment that came in contact with water, and allow watercraft to completely dry before launching again in another reservoir