Tahoe scientist optimistic clarity loss will be reversed

RENO -- A pioneering researcher at Lake Tahoe has expressed optimism that continued reductions in air pollution and sedimentation will help reverse a 40-year decline in the lake's clarity over the next quarter century.

But Charles Goldman, director of the University of California-Davis Tahoe Research Group, also warned against premature conclusions that "Tahoe has been fixed" -- a trap some have fallen into in the past when the lake showed improvement.

"Despite all the talk about pollution, it remains to this day one of the clearest lakes in the world," Goldman said.

"If we can control sediment and probably more important, the dust, then we can probably bring this under control in our lifetime, or at least your lifetime," he told a crowd of about 100 at the Desert Research Institute.

Goldman, who began studying Tahoe's loss of clarity 43 years ago, was speaking as the winner of the institute's most prestigious annual research award, a $10,000 prize and a pure silver, minted medallion called the "Nevada Medal."

Once visible to depths of more than 100 feet, Lake Tahoe's clarity has declined roughly a foot a year since 1960 due in large part to development around the lake.

Last month, Goldman and his colleagues reported Tahoe was the clearest it has been in 10 years with a white plate used to measure clarity visible as deep as 78 feet. But they admitted they didn't know if that was the result of protection efforts or part of a natural drought cycle.

"We've had times where clarity improved dramatically for as long as five years at a time, only to revert into a decline in the following years," Goldman said Wednesday.

"It shows the importance of long-term data and how very dangerous it is to take a three-year or five-year grant to do research and come to any strong conclusions on environmental or climate changes," he said.

For example, Goldman said he and others spent about 20 years measuring the quality of water flowing into Lake Tahoe "and paying no attention to the atmosphere.

"Now we have found that nitrogen input to the lake is largely from the atmosphere," primarily exhaust emissions from automobiles, buses and trucks, he said. The increased nitrogen fuels algae growth that reduces clarity.

Desert Research Institute President Stephen G. Wells said Goldman's persistence in documenting Lake Tahoe's environmental decline was a driving force in the dramatic increase in scientific attention to the plight of the lake over the past decade.

Goldman was the chairman of UC-Davis' Division of Environmental Studies from 1988-1992 and was founding director of its Institute of Ecology. His work includes studies in Africa, Europe, Central America, South America and eight research expeditions to Lake Baikal in Siberian Russia.

"I've seen most of the large lakes in the world and in my opinion Lake Tahoe is the single-most beautiful sub-alpine lake in the world," Goldman said.

"I don't think Lake Geneva can hold a candle to it."