Seeing Clearly at Lake Tahoe

Everyone at Lake Tahoe is hoping that history—or at least a very specific historical fact—will repeat itself. Tahoe—a 23-mile-long, 12-mile wide, nearly 1,600-foot-deep lake nestled in the Sierra Nevada—regained its lost clarity after most of the surrounding forests were clear cut in the 1800s and erosion was rampant. That's particularly good news now, considering that Tahoe is again losing its famed clarity.

Alan Heyvaert, a researcher at the University of California, Davis, has taken sediment and algae samples to discover that Tahoe's clear blue water probably became significantly murkier in the late 19th century after there was considerable logging in the area. However, after the turn of the century, when the logging stopped and the impacts were gone, the lake's clarity returned.

In the 1950s and 1960s, rapid urbanization began in the Tahoe Basin. With roads crisscrossing the area and housing tracts built, Mother Nature could no longer filter out sediment and nutrients from stormwater before it hit the lake. Tahoe's famed transparency started getting worse by a rate of more than a foot a year, a trend that continues. But unlike the environmental impacts of the 1800s, urbanization isn't going to stop.

“From a medical perspective, it's a different set of symptoms,” says Heyvaert. “What we have now can be looked at as a chronic illness, contrary to the period of ill health we had in the 1800s.” The good news from studies about the lake's past, Heyvaert says, is that the lake can recover relatively quickly if given the opportunity.

Dave Roberts, assistant executive director of the environmental watchdog group the League to Save Lake Tahoe, would like to see history repeated. “It's really the hope we have in the Tahoe Basin, that the restoration and mitigation being proposed are going to adequately control sediment loading and arrest the decline in clarity,” Roberts says.

Tahoe officials have rallied around a remedy for the endangered lake, known as the Environmental Improvement Program (EIP). The restoration effort has brought focus to lake-saving efforts throughout the Tahoe Basin, which incorporates two states, five counties and about 50,000 residents. The EIP outlines programs that will cost $900 million, with funding divided up between the federal, state and local governments.

“I don't know of any other place that has put together an environmental improvement plan that clearly identifies the roles for the various levels of government to play, as well as the private sector,” says Pam Drum, spokeswoman for the bistate Tahoe Regional Planning Agency, which developed the EIP. “We can serve as a model for other areas.”