For those of us who grew up in the area and spent summer weekends at Tahoe, the memory of the stunning clarity of the water remains, and the good news is that it still is very clear.
It can be kept that way with proper harvesting of the surrounding forests to prevent the disaster of a fire aftermath which would dirty it for years.
An excerpt.
Manage Tahoe forests to keep the lake clear
By Charles Goldman - Special To The BeePublished 12:00 am PDT Wednesday, September 20, 2006
You may not be able to see more than 100 feet below Lake Tahoe's surface as you could 120 years ago, but for now it remains one of the clearest large lakes in the world. There is a growing understanding that everyone loses if its water quality deteriorates. But one major wildfire in the Tahoe Basin would reduce the lake's clarity enormously.
Since I began my studies of Lake Tahoe in 1959, it has lost a third of its remarkable transparency. Nitrogen and phosphorous levels have increased, and development along its shores has accelerated the amount of nutrients and sediments in the lake.
A high intensity fire would lead to significant erosion in the Tahoe Basin. Post-fire rains and snowmelt would wash mud, ash and debris into the lake. The basin would trap a great amount of toxic pollutants and particulate matter from the fire's smoke, which would ultimately settle into the lake itself.
For centuries, forests in the basin helped keep the lake clear. Root systems held soils on the slopes and healthy forests helped clean the air. Then, in 1857, gold and silver were discovered in the Comstock Lode at Virginia City, Nev. Forests were cleared and the wood was used to shore up mines and build railroads.
Erosion increased dramatically during the Comstock era and heavy sediment loads degraded Lake Tahoe's clarity. Fortunately, the immediate impact of the Comstock mining subsided and sediment loads eventually dropped to about 20 percent of their peak levels. But the effects of the era may still haunt the lake.
When Comstock mining ended, white fir and brush grew back densely in the basin. Human fire suppression efforts over the past century extinguished the lightning-ignited blazes that otherwise would have naturally thinned the forests. Now the forests are so overcrowded and riddled by bark beetles that they pose a major fire hazard. Catastrophic fire, in turn, poses the most significant, immediate threat to Lake Tahoe's clarity. One wildfire could send the lake back to Comstock conditions. It could stay that way for quite a while, too: Because of the lake's tremendous depth, small particles of dust and sediments remain suspended in the water for years. Those particles reflect light and decrease its penetration, both of which diminish the lake's transparency.
Imagine what would happen should rain wash 50 million cubic yards of post-fire topsoil and debris into Lake Tahoe, as happened to Lake Isabella following the McNally fire in and around the Giant Sequoia National Monument in 2002. Or if 700 million cubic yards of debris clogged Tahoe's watershed, as it did the Santa Ana River watershed after the Old, Grand Prix and Padua fires in Southern California in 2003.
