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Lake Tahoe growing warmer but bluer too, report says

August 12, 2008 |  1:30 pm

Lake Tahoe

Though Lake Tahoe continues to warm, the clarity of its waters were little affected by smoke and ash from last summer's Angora fire and the lake has continued to turn bluer, according to a report released today by the UC Davis Tahoe Environmental Research Center.

Deposits of nitrogen and phosphorus from smoke and ash were estimated to be 2.5 to 7 times their normal summer rate, but was still only 1% to 2% of all deposit sources annually.

Because 2007 was the 14th driest year on record, the impact of pollutants such as those phosphorus and nitrogen particles being carried into the lake by streams and urban runoff has thus far been negligible, the report said. Scientists warned that the long-term effects, especially in the 3,100-acre burn area of the Angora fire, may not be known for several years.

The 60-page "Tahoe: State of the Lake Report 2008 " was the second such report completed by scientists from the university who have monitored Lake Tahoe for nearly 40 years. Writes Geoffrey Schladow, the center's director, in the introduction:

This report is not intended to be a scorecard for Lake Tahoe. Rather, it sets the context for understanding what changes are occurring from year to year: How much did the Angora Fire affect Lake Tahoe? Was Lake Tahoe warmer or cooler than the historical record last year? Are algae increasing? And, of course, how do all these changes affect the lake’s famous clarity?

All those answers, and more (including some nifty graphs), in that report.

-- Tami Abdollah

Photo: A 1997 photo shows a greenish algae caused by sediment flowing into Lake Tahoe that discolors portions of the deep blue water. Some worried the entire lake could eventually become gray-green. Credit: Bob Chamberlin / Los Angeles Times