Lake Tahoe's famed clarity slightly decreased from its 2008 level in 2009, scientists announced last week.
The lake was clear to an average depth of 68.1 feet in 2009, according to research unveiled Aug. 10 from the University of California, Davis, where scientists have been monitoring lake clarity for more than 40 years.
Clarity was measured at 102.4 feet in 1968 when scientists first began measuring Lake Tahoe. The lowest reading was 64 feet in 1997.
The latest test results are cause for optimism, said Geoff Schladow, director of the UC Davis Tahoe Environmental Research Center.
"For the last eight or nine years, the science has shown that fine particles are the major cause of clarity decline," Schladow said. "Today, we have many projects in the basin that are being designed to better retain these fine particles and keep them out of the lake."
Practices aimed at reducing the amount of fine sediment that reaches the lake are working, Schladow said, as evidenced by the fact 2009 witnessed much higher levels of participation than 2007 or 2008.
"Holding steady on lake clarity is a tremendous accomplishment, considering the increased precipitation and runoff we experienced," said Joanne Marchetta, executive director of the Tahoe Regional Planning Agency.
TRPA has implemented a number of erosion control measures throughout the basin in an attempt to protect lake clarity.
"We believe the environmental restoration work we've been engaged in over the last decade is taking hold and making a positive difference," she said.
Researchers also noted that 2009 summer clarity ratings were better than 2008 summer clarity ratings by 10 feet.
Carl Young, program director for the League to Save Lake Tahoe, did not share in the celebratory optimism, as he noted that clarity actually declined by one foot and a half from 2008 to 2009.
"Anytime you get a reading in the 60s, it is cause for concern," Young said. "Also, we still need to do a lot more to not only maintain, but restore lake clarity to Tahoe."
