New invasive weed found in Lake Tahoe, sparks concerns

Saturday, April 3, 2004 | 10:56 a.m.

SOUTH LAKE TAHOE, Calif. - Local officials battling an invasive weed that causes environmental problems at Lake Tahoe are facing more bad news: the discovery of another non-native aquatic plant.

The curly leaf pondweed has turned up at Tahoe Keys on the Sierra Nevada lake's south shore, said Lars Anderson, a U.S. Agriculture Department botanist.

Last week, four pumps were installed in the same area in an effort to stop the spread of the Eurasian water milfoil, a weed that was found in Tahoe in the 1960s.

"The main thing is we found a different plant," Anderson told the Tahoe Daily Tribune. "It's an exotic species and we know it spreads fast. I don't know how it will compete with milfoil. In the long run it may become the dominant plant."

The milfoil clogs Tahoe Keys and at least 10 other places in Tahoe each summer, making the water less attractive to native fish.

The aquatic weed also helps fuel algae growth, which threatens to turn Tahoe's famous clear, blue waters green.

For boaters, the milfoil means trouble because it gets tangled on propellers, which chop it up and help spread it along the shoreline.

Richard Horton, co-owner of the Tahoe Keys Marina, expressed concern over the latest discovery.

"Oh, boy. Once we're done killing the milfoil we might end up having another plant to contend with," Horton said.

Anderson speculated that the pondweed was brought by a boater from the Sacramento Delta, where the plant is common.

He said the troublesome weed could be more widespread at Tahoe, but that won't be known until a survey is completed later this spring.

The milfoil grows so fast it has to be mowed May through October with a special harvester.

The agency charged with protecting Tahoe's environment approved a request for the four water pumps designed to combat the milfoil.

"We thought it was very important ... to get them in the water before the milfoil growth season begins," said Julie Regan, spokeswoman for the Tahoe Regional Planning Agency. "We think it's going to be good for the environment, and we're hoping it will make a positive difference in the Keys area."

The pumps, which bring oxygenated water to the bottom of the lake, are designed to help diminish stagnant water conditions that promote growth of milfoil.

Last year, Anderson and Tahoe Keys property owners proposed a herbicide test to see if it would eradicate the weed but state regulators opposed the request.