Lake Tahoe clarity held steady in 2009 for the ninth year in a row, but remains significantly poorer than in previous decades, according to UC Davis scientists who have monitored the lake for more than 40 years.
The lake was clear to an average depth of 68.1 feet in 2009, the researchers found.
That’s down from 102.4 feet in 1968, when UC Davis researchers first measured the lake’s clarity.
Geoff Schladow, director of the UC Davis Tahoe Environmental Research Center, said the latest test results may be cause for some optimism.
Even though precipitation was much higher in 2009 than in 2008 or 2007, the annual average clarity remained relatively stable, Schladow noted. Rainfall and snowmelt wash water-clouding particles into the lake.
Another hopeful finding: 2009 summer clarity readings were much better than 2008 summer readings. Overall, clarity during the summer months of 2009 was 10 feet better than in summer of 2008.
UC Davis researchers measure the lake's clarity throughout the year by lowering a white Secchi disk, named after its inventor, Italian scientist Angelo Secchi, at two fixed locations. The depth at which the disk, the size of a dinner plate, disappears from sight is referred to as the Secchi depth, a measurement of clarity. For more information, visit http://news.ucdavis.edu./
The lake was clear to an average depth of 68.1 feet in 2009, the researchers found.
That’s down from 102.4 feet in 1968, when UC Davis researchers first measured the lake’s clarity.
Geoff Schladow, director of the UC Davis Tahoe Environmental Research Center, said the latest test results may be cause for some optimism.
Even though precipitation was much higher in 2009 than in 2008 or 2007, the annual average clarity remained relatively stable, Schladow noted. Rainfall and snowmelt wash water-clouding particles into the lake.
Another hopeful finding: 2009 summer clarity readings were much better than 2008 summer readings. Overall, clarity during the summer months of 2009 was 10 feet better than in summer of 2008.
UC Davis researchers measure the lake's clarity throughout the year by lowering a white Secchi disk, named after its inventor, Italian scientist Angelo Secchi, at two fixed locations. The depth at which the disk, the size of a dinner plate, disappears from sight is referred to as the Secchi depth, a measurement of clarity. For more information, visit http://news.ucdavis.edu./
