Lake Tahoe clarity has stabilized over past decade
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Despite a dip last year, Lake Tahoe's clarity has stabilized over the past decade. Last year's average clarity was about 70 feet compared to 75 in 2012.
Even with last year's decline, researchers at the UC Davis Lake Tahoe Environmental Research Center report that the lake's clarity level has flattened out, which is actually good news.
"Now, you may take the glass-half-empty approach and say we're not making improvement," says the center's director Geoff Schladow, "but the important thing to realize is that for 25 years before that the clarity was getting worse, year after year."
The lake is still considerably shy of the target clarity set by state and federal regulators of 97.4 feet.
"What's going to happen now," Schladow explains, "we're expecting clarity will improve, but it's not going to get to where we want for maybe 20 or 30 years."
Before Tahoe was developed, he says marshes, wetlands, and meadows trapped fine particles so they didn't enter the lake and projects restoring those natural resources have proven most helpful now.
Nevada and California's ongoing drought conditions have also played a role.
"This is possibly the only beneficial impact of the drought that I can think of," Schladow says, "is that because this winter we've had so few storms, fewer fine particles and fewer nutrients have been washed into the lake."
Since 1968, researchers have measured the lake's clarity several times each year by lowering a white disk into the water to see how long it remains visible from the surface.