Study: Lake Tahoe Could Change Radically in 10 Years

A new University of California-Davis study predicts that climate change will irreversibly alter water circulation in Lake Tahoe, radically changing the conditions for plants and fish in the lake -- and it could happen in 10 years.

One likely result would be a warmer lake overall with fewer cold-water native fish and more invasive species, such as large-mouth bass, bluegill, and carp.

Still unclear is how the changes would affect the lake's clarity and cobalt-blue color, which have helped to make the Tahoe Basin an international vacation destination.

The new findings were announced March 18 at a Tahoe scientific conference by three lake experts from the Tahoe Environmental Research Center at the university -- Director Geoffrey Schladow, Associate Director John Reuter and postdoctoral researcher Goloka Sahoo.

"What we expect is that deep mixing of Lake Tahoe's water layers will become less frequent, even non-existent, depleting the bottom waters of oxygen. This will result in major, permanent disruption to the entire lake food web," Schladow said. "This is not unheard of," he continued. "Anoxia (oxygen depletion) occurs annually in most lakes and reservoirs in California in the summer. But Tahoe has always been special. It's been above and beyond such things.

"A permanently stratified Lake Tahoe becomes just like any other lake or pond. It is no longer this unique, effervescent jewel, the finest example of nature's grandeur."

Schladow said research is ongoing to determine if lowered global greenhouse-gas emissions would significantly slow the lake's decline, or even prevent it.

The new study combined 40 years of weather data in the basin with mathematical models of global climate to create likely scenarios of future climate conditions at Lake Tahoe. Using those scenarios, the team employed a lake physics model to see how various combinations of probable air temperatures, cloudiness, and wind speed would affect the mixing of water layers in the lake.

Currently, Lake Tahoe water mixes, on average, every four years. The deepest mixing typically occurs in late February. This winter -- a particularly cold and snowy one -- Lake Tahoe experienced mixing throughout its entire 1,644-foot depth.

This mixing has profound ecological and water-quality impacts. Deep mixing moves nutrients from the lake bottom to the water surface, where they promote the growth of algae. And it takes oxygen from the surface and distributes it throughout the lake, which supports aquatic life.

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