A new study carried out by a team of researchers at the University of California, Davis, now solves the mystery and gives an explanation for the remarkable color of the lake. It appears that the algal concentration in it is responsible for its wonderful shade, and not its clarity.
A postdoctoral researcher at the University of California and one of the authors of the study, Shoshei Watanabe came up with a Blueness Index to see which were the factors that determined the color of the lake. In order to do this, she used a tool that is able to capture light and other information from a NASA Jet Propulsion Lab research buoy.
Using this instrument, the researchers collected data above the lake and looked at the link between clarity and color by means of hyperspectral radiometers.
They explained that blueness is determined by the algal concentration in the water and clarity is given by sediment. Algal concentration is very much influenced by the amount of nutrients, i.e. nitrogen and phosphorus. The higher the amount of nutrients, the less blue the lake is.
“Less nutrients washed into lake, nutrients that helped algae to grow. So nature has shown us what happens if nutrients get into the lake. In that way, Lake Tahoe has shown us what it needs to be blue and clear again,” said Geoffrey Schladow, who is the director of Tahoe Environmental Research at University of California.
The variation of nutrients, sediment and levels of algae is the reason why Lake Tahoe is sometimes extremely blue and other times it is not. This variation tends to differ from one season to another, usually being at its bluest during the summer. This is great news for tourists who most often chose this period of time to visit the lake.
Until now, it was thought that clarity was responsible for the color of the lake but the researchers said that it actually has nothing to do with it.
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