Lake Tahoe's Clarity Improves - KTVN Channel 2 - Reno Tahoe News Weather, Video -

Lake Tahoe's Clarity Improves

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After decades of decline, Lake Tahoe's water clarity is on the mend. Researchers with UC Davis say they are seeing the best numbers since 2002, at 75.3 feet. The levels are 6.4 feet better than 2011. There is still work to be done though. The restoration target is about 97.4 feet.

A lot of different elements go into Lake Tahoe's clarity, including weather patterns, invasive species, and the presence of humans.

"It's important that we do the work to keep Tahoe blue," Heather Segale, UC Davis Tahoe Environmental Research Center Education and Outreach Director said. "Every generation has their job and at Lake Tahoe, we feel ours is to protect this lake."

Water clarity levels have been recorded since 1968, when levels were at 102.4 feet.

But clarity declined, with the worst recorded numbers coming in 1997 and 1998, 65.1 feet.

The number is the average of 22 measurements taken per year, using a 10-inch Secchi disk.

"You lower it down into the lake and you just watch for it to disappear," Segale said. "When it disappears from view, you bring it back up till you can see it again and then average the two measurements."

One of the biggest factors of clarity is urban water runoff.

Small particles and sediment end up in the lake and is usually worse during the snow melt.

Scientists say urban runoff has gotten worse as homes and roads were built, taking away the natural filtration of the land.

"When we drive around the lake and we drive over the soil that ends up on the roads, we are grinding those particles finer and finer," Segale said.

Segale says last year's dry winter may have played a role in the improved clarity.

But in recent wet years, water clarity has still improved.

"Certainly, in drought years, the lake heals itself, which is great that it can do that," Segale said. "And then in big storm years, like 1997, the flood, the clarity was quite reduced."

Efforts are also underway fight invasive species like the Asian Clam and Quagga Mussell.

While algae decreases lake clarity, some native species do their part.

Like tiny plankton that eat the algae.

Along with research, the Tahoe Center for Environmental Science also has a program for the public including a 3D movie that talks about Lake Tahoe. It's open to the public Tuesday through Friday, from 1pm to 5pm.

Written by Paul Nelson
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