Scientists Discover What Makes Lake Tahoe Blue

For a long time, it has been firmly believed that Lake Tahoe’s iconic blue tint is due to its clarity. “That tells you something about both the color and the clarity of the lake”.

That’s one conclusion of new research into Tahoe’s unique characteristics scientists released Thursday with important management implications for the landmark alpine lake. In all honesty, they have every reason to be proud as the lake is so famous for its crystal blue waters that researchers take turns to study its composition.

Watanabe further explained to Reno Gazette Journal that the results, when combined to the other measurements and findings to determine the clarity of the lake, only showed that the blue color and clarity of the lake is totally opposite.

But those are different things, with different environmental factors coming into play to determine how clear and how blue the lake is at any given time. In creating the Blueness Index, Watanabe and his colleagues found the lower the algal concentration, the bluer the lake.

The report recently released by the TERC researchers also indicate that climate change, drought, and algae concentration are the strongest factors that have affected the color of the lake. Clarity is measured by observing the depth at which a dinner-plate-sized white disk remains visible when lowered into the water.

Lake Tahoe image via Shutterstock. This usually occurs in the summer period, when very few algae nutrients are found in the water. Clarity is controlled by sediment. That work should continue, Schladow said.

For the past three years, UC Davis researchers have been measuring the degree of blueness in Lake Tahoe using a NASA research buoy. Those include nitrogen, deposited from the air, and phosphorus, washed into the lake from throughout Tahoe’s watershed.

However, Watanabe said clarity should not be dismissed as it shows that nutrient input and algae concentrations should be managed closely in order to keep the lake clear and blue.

Or, benefits of the new research can be summed up more simply.

Geoffrey Schladow, the director of Tahoe Environmental Research Center at UC Davis declares these findings a remarkable achievement in terms of better understand how Lake Tahoe works.