Tahoe: A lake of troubled water

Tahoe Daily Tribune

July 24, 1997
By Patrick McCartney
Tribune Senior Staff Writer

Until recently, most Tahoe Basin residents took Lake Tahoe's famed clarity for granted.

If the water's transparency was not as magnificent as when author Mark Twain described seeing speckled trout through 150 feet of water, its clarity was still impressive.

Even as the basin's population exploded in the decade following the 1960 Winter Olympics at Squaw Valley, researchers could still see a white disk through 100 feet of water.

But those closest to the lake already realized that, beneath the surface, the nation's largest Alpine lake was in trouble. For years, however, they had trouble convincing the public.

"I was alarmed and discouraged that most of the lakeside viewers did not believe the lake was in trouble," said Dr. Charles Goldman, a University of California, Davis scientist who founded the Tahoe Research Group in 1967. "It was hard to convince anyone except scientists that the lake was in trouble."

Yet, the evidence mounted. After measuring the lake's clarity repeatedly over four years, scientists realized the results were incontestable. Nutrients that feed algae were streaming into the lake, and the growth of algae was leading to a significant loss of clarity.

"Once we got the long-term data, we knew the lake was in trouble," Goldman said. "The lake is still one of the clearest large lakes in the world, but if you project the trend out for 30 years, we have an ordinary lake."

Thanks to dozens of researchers and the hundreds of research projects they have conducted at Lake Tahoe, scientists today believe they understand what is occurring.

Simply put, Lake Tahoe's aging process, which would turn it from a clear, sterile mountain lake to a green lake rich in nutrients, has been greatly accelerated by human development.

The aging process, called eutrophication, would ordinarily take millions of years but, with soil erosion from development and air pollution providing food for Lake Tahoe's algae, scientists believed the point of no return was only decades away.

Since 1968, Lake Tahoe's clarity plummeted from 102 feet to 72 feet in 1995. Last year, the clarity rebounded to nearly 80 feet, but researchers emphasize that a single year's data is relatively meaningless. The 30-year trend shows an annual loss of visibility of 1.3 feet, even though there have been individual years, and one period of five years, when clarity improved.

"It's premature to say the lake is getting better based on (this improvement)," said Bob Richards, a researcher and spokesman for the Tahoe Research Group. "It would be nice to see a positive trend; we're sure looking for one."

Lake Tahoe's water quality will top the agenda at the two-day Lake Tahoe Presidential Summit beginning Friday. President Clinton and Vice President Gore are expected to commit the federal government to assist efforts to restore Lake Tahoe's most prized asset.

While officials have not announced what the federal government is likely to do, researchers have known for some time what is necessary. While the federal government and states of California and Nevada have invested more than $300 million in the basin, far more remains to be done.

The Tahoe Regional Planning Agency has identified $542.8 million in projects needed to restore the lake's water quality. Among them are the purchase of environmentally sensitive land, the restoration of the basin's degraded wetlands and the construction of erosion-control devices to reduce the amount of soil pouring into the lake.