Untitled

Abstract

Spectral irradiance has been measured as a function of depth in Crater Lake, Oregon, and Lake Tahoe, California. In Lake Tahoe, Secchi disk observations and submarine photometer measurements have been recorded year round since July 1967. Also, in Lake Tahoe, beam transmittance has been measured as a function of depth. From these data the radiant energy input and certain optical properties of the two lakes are presented. Since color is a principal esthetic feature of these lakes, a complete color analysis is also presented. This information provides an objective standard with which to compare possible future changes in the optical properties and in the esthetic appearance of Crater Lake and Lake Tahoe. The method can be applied generally to quantify the optical deterioration of any aquatic habitat and can detect such deterioration before it is noticeable by casual visual observation.