Oroville Mercury-Register

Future of Lake Tahoe clarity in question as fires worsen

- By Sam Metz

CARSON CITY, NEV. » When a wildfire crested the mountains near North America’s largest alpine lake, embers and ash that zipped across a smoky sky pierced Lake Tahoe’s clear blue waters.

The evacuation order for thousands to flee their homes has been lifted, but those who returned have found black stripes of ash building up on the shoreline — a reminder that success fighting the Caldor Fire won’t insulate the resort region on the California-Nevada line from effects that outlast wildfire season.

Scientists say it’s too soon to draw conclusion­s about the lasting damage that record-setting wildfires will have on Lake Tahoe. But they’re not wasting time. Many expect to bring their research plans to the Tahoe Science Advisory Council at a meeting Thursday.

Scientists funded by California, Nevada and the League to Save Lake Tahoe are researchin­g lake clarity and biodiversi­ty during and after wildfires. They’re using collection buckets — some loaded with glass marbles — to capture and measure the size and quantity of particles and pollutants from wildfires that have sullied the normally crystal-clear waters. They’re studying how particles enter the lake, how they move around it and the effect on algae production.

The clarity of the iconic alpine lake can vary even without catastroph­ic wildfires. On average, Lake Tahoe is clear 65 feet (20 meters) below the water’s surface. Through wildfire season, scientists stationed near the lake’s center have only been able to see 50 feet (15 meters) below the surface — a reduction they aren’t sure is due to particles, algae or simply lack of sunlight, said

Geoff Schladow, professor of civil and environmen­tal engineerin­g and director of the University of California, Davis’ Tahoe Environmen­tal Research Center.

“My feeling is, in some ways, it may look worse than it is,” Schladow said. “What smoke in the basin actually does, particular­ly when it lasts for months, is something we don’t really know. We’re finding that out as we speak.”

Smoke from Northern California wildfires has cloaked the Lake Tahoe basin in some past years. But as blazes have grown in size and intensity — partially due to climate change, scientists say — smoke from wildfires inside and outside the basin that has sat atop the lake for two to three months in the past two wildfire seasons has exceeded the expectatio­ns of many residents and tourists who flock to the deep blue lake for its clean alpine air and

 ?? RICH PEDRONCELL­I — THE ASSOCIATED PRESS FILE ?? Freya Mayo, left, and her sister Evie, of London, try out a paddle board on Lake Tahoe near South Lake Tahoe.
RICH PEDRONCELL­I — THE ASSOCIATED PRESS FILE Freya Mayo, left, and her sister Evie, of London, try out a paddle board on Lake Tahoe near South Lake Tahoe.

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