Lake Tahoe-area towns at risk of future flooding, UC Davis scientists warn in annual report

Water in Lake Tahoe could rise to unprecedented levels, potentially placing communities downstream in jeopardy, according to a study from environmental scientists at UC Davis’ Tahoe Environmental Research Center.

In the past two years, California saw brutal heatwaves and droughts shrink Lake Tahoe’s water level to a point so low that some boats couldn’t be launched. However, that’s expected to change. While temperatures aren’t projected to cool off, Lake Tahoe could see a rapid depletion of its snowpack and an influx of water during the coming years.

“The lake is going to be low in the future and there will be droughts. We’re going to have a similar amount of average precipitation, but the fraction of snow and rain is going to change,” said Professor Geoffery Schladow, director of the Tahoe Environmental Research Center.

Right now, about half of Tahoe’s precipitation is snow, contributing to the Sierra snowpack, one of California’s most important water resources. But if the hot temperatures intensify and water comes down as rain, then the rainfall will fill the lake’s stream quicker and cause the existing snowpack to melt.

When that happens, the peak streamflow of the lake could triple its historic rates and the water level could rise nearly a foot every day, according to the State of Lake Tahoe report.

There is a six-foot difference between the rim of the lake and the top of the dam.

“Literally in a matter of days, the water can be released in an uncontrolled fashion,” Schladow said.

Towns located downstream from the lake’s natural shore, like Truckee or Reno, could suffer extreme flooding, which wouldn’t be a first. In 1997, the Truckee River flooded and caused millions of dollars in damages to the Reno-Sparks area in Nevada.

“In the future, it’s going to be even bigger,” Schladow said.

There are 63 streams that come into Lake Tahoe. If all flow at record high levels, the lake water levels would rise at a rapid rate and cause intense flooding. Yet another harrowing sign of the impact climate change will have on the state during the upcoming decade.

“This isn’t just a Tahoe problem, this is going to impact all of California.,” Schladow said. “The snowpack stores a huge amount of water, so if we don’t have the snow packs anymore, if we just have rain, then the dams in California aren’t going to be large enough to hold it all.”