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Lake Tahoe Continues A Warming Trend


Brandon Rittiman for NPR

Lake Tahoe's South Shore as seen from a ski resort's gondola.

Lake Tahoe is famous for its clear waters.

However, clarity for the famous body of water on the Nevada-California border could give way, as the lake gets warmer.

The lake is warming 14 times faster than it has in the past, according to a UC Davis report. 

Geoff Schladow the director of UC Davis Tahoe Environmental Research Center told KNPR's State of Nevada that the warming does a number of things to the lake's environment.

First, it means animals and plants in the lake that are adapted to colder temperature water will be under more stress, and invasive species that might be adapted to warmer water will thrive more. 

While those consequences are problems, the biggest issue caused by the warming is the lack of mixing.

“This warming temperature, particularly at the surface, is changing the way the lake works,” Schladow said. 

Warmer water is lighter than cold water. As the surface water warms and the deeper water stays cold, it is more difficult for the cold and warm water to mix. That is especially problematic because the surface water has more oxygen. When the lake mixes, oxygen gets moved from the surface to the depths of the lake, providing oxygen for animals and plants. 

Lake Tahoe is the largest lake in the world at that elevation, Schladow said, and preserving it depends on us.

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“[Lake Tahoe] changes in response to these new set of conditions," he said. "It’s whether we want to preserve the conditions we value in it or whether we say, well let it be what it will be.”

He warns if we let the conditions of the lake continue to change, it's unlikely we'll be able to reverse it.

Schladow says the agencies managing the lake need to make sure the lake can withstand longer periods of no mixing, which means reducing the conditions that allow for algae blooms. To reduce algae blooms, managers have to stop the flow of nutrients that feed those blooms. The biggest culprits are nitrogen, which comes mostly from car emissions, and phosphorous, which mostly comes from erosion. 

The lake's managers have been working to reduce those two chemicals in an effort to improve the lake's quality, but Schladow wants them to do more.

"What we’re saying now is that’s good, but we may have to do even more to build the lake's resilience," he said.

The study also found more dead and dying trees in the Tahoe area. A new instrument from NASA that will be aboard the International Space Station promises to improve what the researchers know about the stress the forest in the Sierra Nevada, along with other important ecological areas around the globe, is under.

“It’s giving us information that we can use to better understand why bark beetles are spreading in a certain region or why a certain part of the lake is more disease prone and start to consider actions that may be helpful,” Schladow said.

Unlike other satellites, the ISS doesn't follow a set path at a set time, which will allow the instrument to collect data at all times of the day. 


Geoff Schladow, director, UC Davis Tahoe Environmental Research Center 

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