It's getting creepier by the minute out there. To the nightmare cauldron of invasive species that have made inroads into the state's waters, we now add quagga mussels.

The Colorado Division of Wildlife said Tuesday that biologists have found quagga mussel larvae in Lake Granby. DNA tests performed by the DOW and the Bureau of Reclamation confirmed the invasive mussel's presence.

Quagga mussels are slightly larger cousins of zebra mussels, which have spurred a rash of boat inspections around the state since their discovery last fall at Pueblo Reservoir.

Like zebra mussels, quaggas reproduce at a phenomenal rate. They can clog water treatment systems, pipelines and boat engines and can strip aquatic ecosystems clean by consuming plankton. Apparently, the Eurasian mollusks were carried to the U.S. in ship ballast water.

Quaggas turned up in Lake Michigan in 2006, and by early 2007 they had invaded the West at lakes Mead, Havasu and Mojave on the lower Colorado River and two aqueducts that supply water to Arizona and Southern California.

So far, the mussels have not made it upriver to Lake Powell, where administrators have taken a tough stand to prevent their spread - including quarantining boats and brandishing fines as high as $5,000 at boaters who fail to sterilize their boats or have them certified mussel-free.

The discovery at Lake Granby means quagga mussels have been detected for the first time in Colorado River headwaters. The mollusks might turn up anywhere along the river. They also could be pumped to the Front Range through the Big Thompson Watershed.

Wildlife division spokesman Tyler Baskfield said the concentration of quagga larvae, known as veligers, in DNA samples taken from Lake Granby was small.

Based on the DNA samples, he said, biologists have deemed the risk of quaggas spreading to be less than that of zebra mussels from Pueblo Reservoir.

No decision has been made yet on whether the DOW or some other agency will start inspecting boats at Granby.

As with zebra mussels, boaters are asked to keep their craft clean, drained and dry to inhibit the spread of quaggas.

Funding kicked in this month to help the DOW and State Parks conduct boat inspections. The state legislature approved $6 million in general funds to help with invasive-species-related inspections.