KINGS BEACH (AP) The bistate agency charged with protecting Lake Tahoe has declared an emergency over the threat posed by the spread of invasive aquatic species at the nation's largest alpine lake.

Tahoe Regional Planning Agency governing board members said their passage Wednesday of a resolution declaring the emergency would expedite the planning and funding for the looming battle against quagga mussels, milfoil and other non-native species.

Since the January discovery of quagga mussels in Lake Mead near Las Vegas, officials have expressed concern about their spread to Lake Tahoe. The invasive mollusk, which has overrun the Great Lakes, can be spread by boats or birds.

If the mussels reach Lake Tahoe, they will disrupt its delicate food chain, biologists said.

They also will clog water pipes, and damage boats and docks by attaching themselves to underwater surfaces.

"Once in a system, it's there and it's virtually impossible to get rid of," said Steve Chilton, chief of Tahoe Regional Planning Agency's environmental improvement branch.

Preventative strategies include boat washing stations where owners can wash vessels before putting them in the lake.

"Boats are the most serious threat," said Phil Brozak of the U.S. Army Corps of Engineers. An agreement about how to proceed probably will be reached within the next two weeks, he said.

"The issue is really our collective concern for the Lake Tahoe Basin from the threat of invasive species," Tahoe Regional Planning Agency spokeswoman Julie Regan said.

The state of emergency will open new doors for funding, and will signal to other agencies the importance of dealing with the issue, she said.

While action against quagga mussels is a top priority, officials also expressed concern over other invasive species, including Eurasian watermilfoil, curlyleaf pondweed, the New Zealand mud snail and zebra mussels.

Officials already have found Eurasian watermilfoil in the lake.

The underwater weed crowds out native vegetation and contributes to declines in the lake's famous clarity.

At a two-day conference in nearby Incline Village, Nev., early this month, scientists and government officials agreed invasive species pose a major threat to Lake Tahoe's future and efforts against them need to be stepped up.