Conservation education

Excerpt

In 1872, the great American author Mark Twain remarked about Lake Tahoe:

So singularly clear was the water that when it was only twenty or thirty feet deep the bottom was so perfectly distinct that the boat seemed floating in the air! Yes, where it was even eighty feet deep…. Down through the transparency of these great depths, the water was not merely transparent, but dazzlingly, brilliantly so.

One hundred and twenty years later, Lake Tahoe is still renowned for its exceptional clarity of water. Unfortunately, this unique trait has been in jeopardy during recent decades. Currently, water clarity is diminishing at a rate of about one foot per year and since 1968 there has been a 20 percent loss in transparency (Tahoe Regional Planning Agency (TRPA) 1988, 1991).

Under natural conditions, such as those present when Mark Twain made his observations, water clarity would have changed very slowly as a result of eutrophication. The disturbance and development of the Lake Tahoe watershed, however, has greatly accelerated the eutrophication process. This human activity has greatly increased the amount …