p1 Once murky, Lake Tahoe is clearing up

Urban stormwater runoff has long been one contributor to reduced clarity at Lake Tahoe. Most of that runoff occurs during the winter and spring, when rain and snowmelt carry small, inorganic particles from the land into the lake.


Data released today by the University of California, Davis Tahoe Environmental Research Center and the Tahoe Regional Planning Agency reported the average annual clarity level for 2011 at 68.9 feet, a 4.5-foot improvement over 2010, when average clarity levels were the second-worst on record.

Winter clarity last year continued a decade-long pattern of improvement, while summer clarity continued to decline at the same rate that it has since the late 1960s, when monitoring began.

Average annual clarity in the past decade has been better than in recent decades. In 1997-1998, annual clarity reached an all-time average low of 65.1 feet. From 2001-2011 the average clarity was 70.6 feet.

Yet this year’s value is still more than two dozen feet away from the clarity restoration target of 97.4 feet set by federal and state regulators.



Read more at the original source here.