Flagship lake not above environmental change

A lake considered by many Americans as the embodiment of nature's grandeur is feeling the bite of climate change.

Fragile beauty: the Tahoe could become a poster child for the environmental movement in the USA

Fragile beauty: the Tahoe could become a poster child for the environmental movement in the USA

Lake Tahoe, nestled in the Sierra Nevada mountains straddling the border of California and Nevada, is known for its phenomenal clarity and cobalt-blue colour, with its stunning water and locations making it a leading holiday destination for Americans.

But a study carried out by scientists from the University of California's Davis campus suggest that the lake will undergo radical ecological change over the coming decade as climate change starts to impact.

The changing climate is likely to irreversibly alter water circulation, say the researchers, which will lead to a warmer lake and a drop in numbers of native cold-water fish.

Invasive species such as large-mouth bass, bluegill and carp are likely to take their ecological niche.

Geoffrey Schladow, director of the Tahoe Environmental Research Centre, said: "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.

"This is not unheard of, 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."

Equally worrying, he said, is the likelihood that when the oxygen is gone, phosphorus that is currently locked up in the lake-floor sediments will get released.

This phosphorus will eventually reach the lake's surface, where it will fuel algal growth. Algae blooms can cause many problems, including reduced lake clarity, unpleasant odours and bad-tasting drinking water.

Sam Bond



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