"The news is not good," said Lars Anderson, a U.S. Department of Agriculture scientist who has tracked the movement of invasive weeds in Tahoe's waters. "How do we know we've got a problem? We're seeing it spread."

Among other threats, smallmouth bass have the potential to damage the lake's natural food web, and Eurasian water milfoil, an underwater weed, may crowd out native vegetation and contribute to declines in water clarity.

"People are freaking out. And we should," said University of Nevada, Reno researcher Sudeep Chandra.

The sense of urgency stems primarily from the threat posed by the quagga mussel, an invasive mollusk that was found thriving in Lake Mead four months ago.

Experts fear the mussel could be transported to Lake Tahoe by boats and cause widespread environmental and economic problems.

Quagga mussels are close relatives of the zebra mussel, a species that can latch on to most solid surfaces and quickly reproduce.

John Singlaub, executive director of the Tahoe Regional Planning Agency, said the battle against invasive plants and animals should be a priority.

He said he plans to discuss funding for the program with Nevada and California officials.