Lake Tahoe was slightly clearer in 2007 than 2006, researchers said Monday, and a new analysis shows the lake's historic clarity loss may have slowed down.

The latest numbers from scientists with the University of California, Davis, Tahoe Environmental Research Center reveal that a person could see through Lake Tahoe's waters to an average depth of 70.2 feet in 2007, 21Ú2 feet greater than measurements taken during 2006.

More significantly, researchers say, is a new model that shows the roughly foot-per-year clarity loss in the lake since 1968 has slowed.

"From 1968 to 2000, there was a near-continuous decline in lake clarity," Geoffrey Schladow, director of the research center, said in a statement from UC Davis and the Tahoe Regional Planning Agency. "There were several years at a time when things seemed to improve, but invariably we returned to the same trend. But since 2001, we have had seven years in which the clarity has consistently been better than the long-term trend would have predicted."

Exactly how much the decline in clarity has slowed wasn't calculated by researchers, but John Reuter, associate director of the research center, said clarity decline has slowed "significantly" since 2001.

"There's no other time in the historical record where we see this sort of reduction in rate of decline," Reuter said.

Still, Reuter shied away from calling the slowdown an "improvement."

"It's not that things are actually getting better, it's things aren't getting worse as fast," Reuter said.

The results of the latest study don't include a reason for the slowdown in clarity loss, and researchers cautioned against extrapolating the data too far into the future.

"It is difficult to use data from a small number of years to draw conclusions about when the trend might change from a slowdown in clarity decline to an improvement in clarity," according to the statement.

Nevertheless, researchers are "very guardedly optimistic" about the results, Reuter said.

"We have never seen this before, and we hope it's a trend that will continue," he said.