Since optical water clarity is the first means by which common people and researchers make their judgements on water quality, it is very important that it always be analyzed. As a result, Lake Tahoe’s clarity has frequently been observed and checked, for annual and seasonal changes. The Secchi depth is measured by lowering a roughly 25 cm wide matte white disc plate (the color and size of the disc can vary between studies), into the waters off of the shaded side of the boat. The depth at which the disc disappears when going down, and the depth at which it reappears when coming back up are taken, and the average of these two values is recorded as the final Secchi disc depth. In Lake Tahoe, about every 12 days since 1967, the Secchi depths have been collected midday; since it is an unusually clear lake and it is easily affected by changes in water particles (Jassby et al., …show more content…
By diverging the sewage away from Lake Washington, the lake was able to cut back on its dominant limiting nutrient: phosphorus. As the unbalanced nutrient input levels decreased, phosphorus and nitrogen were able to reach relatively healthy levels, and quickly improvements in the lake's water clarity levels went from 1 meter to 2.8 meters in just six years (Edmondson,