Researchers have discovered that algae concentration was the cause of Lake Tahoe’s blue tint. For years, several experts carried out costly efforts to prevent the loss of the lake’s clarity as it was believed that its clarity and blueness were synonymous.
Geoffrey Schladow, director of the UC Davis Tahoe Environmental Research Center said that they always thought clarity meant blueness in a report, released on Thursday. The assumption that blueness equates to clarity has been laid to rest, after a research conducted by UC Davis scientist Shohei Watanabe along with researchers from NASA’s Jet Propulsion Laboratory and Canada’s Laval University.
“Though it’s really quite subjective, you can now put a number on blueness,” said Schladow.
Researchers have found that algae and blueness are separate. By creating the blueness index, Watanabe and his team found that the lake appeared less blue, if there was less algal concentration. The clarity of the water does not contribute to the blue tint. Researchers have found that the algae concentrations and nutrient input should be managed to keep Lake Tahoe blue and clear.
Algal concentration is dependent on the level of nutrients (nitrogen and phosphorus) which reduces the blue tint while clarity is controlled by a sediment. The drought in the region has reduced the flow of nutrients and sediment, in turn creating a bluer Tahoe Lake. Millions of dollars have been invested to prevent erosion and collect particles that lower the clarity. Over the past three years, Tahoe’s blue color has improved though the research has indicated that work should focus on preventing algae nutrients from entering the lake.
Schladow mentioned that nature has shown what happens if nutrients enter into the lake, and it needs to be clear and blue again. The research has also enabled researchers to understand how Lake Tahoe works.[ Source ]