NASA Explains the Mystery Behind Lake Tahoe’s Blueness

Lake Tahoe is renowned for its blueness -- various stakeholders have been working hard for years to preserve the lake's iconic cerulean hue. It was commonly believed that the lake's blueness was directly proportionate to the clarity of the water, which spurred regulations controlling construction and development along the lake's shore.
As it turns out, Tahoe's blueness is caused by a completely different factor.
According to data collected by a NASA research buoy and released today by the Tahoe Environmental Research Center, algal blooms are responsible for the varying degrees of the lake's blueness. When the lake becomes less concentrated with algae, the water becomes bluer, according to the report.
"We better understand how Lake Tahoe works, and it reinforces the importance of controlling nutrient inputs to the lake, whether from the forest, the surrounding lawns or even from the air," says Geoffrey Schladow, Tahoe Environmental Research Center director. "It's particularly encouraging that blueness has been increasing over the last three years."
The buoy is one of four operated by NASA's Jet Propulsion Laboratory, all of which validate and calibrate data collected by satellites.
"This particular buoy has instruments beneath the water looking up and an instrument on the buoy looking down," explains JPL's Simon Hook. "The combination of instruments in and above the water was used in this study to look at how light is being scattered and attenuated. That tells you something about both the color and the clarity of the lake."