Lake Tahoe waters are collapsing due to drought and climate change

Lake Tahoe’s water levels have dropped so low that water no longer flows into the Truckee River, and salmon are not expected to spawn in a major tributary this year.

Some boat ramps and docks are hundreds of feet from the waterline, and lumps of stringy algae have washed up on beaches, said Geoffrey Schladow, director of the UC Davis Tahoe Environmental Research Center.

“It warns us that things can get a lot worse,” he said.

The declining water level, driven by climate change and drought, comes as the latest insult to the valuable tourist destination located in the Sierra Nevada. The waters have already been clouded by smoke and ash from several wildfires this summer.

Lake Tahoe’s water levels are always fluctuating. It is typically lowest in December and January and then rises in the spring as melting snow from nearby mountains flows down, Schladow said.

“This year we didn’t get that bump,” he said. “It fell more or less since the year before.”

Several boat ramps could not open for the summer season.

And without precipitation changing the game, conditions continue to deteriorate. The water level is usually somewhere between the lake’s natural edge, which sits at 6,223 feet, and a dam at the top of the Truckee River, which is six feet higher, Schladow said. But earlier in the week, it fell just below the rim. By Saturday afternoon, the water level was about half an inch below the edge – and falling, according to preliminary data from the US Geological Survey.

This is because the lake loses about six feet of water each year by evaporation — a rate of about an inch a day, which can rise with strong winds, Schladow said.

“If this next year is just an average year or worse, a dry year, it probably means that the water level this time next year might be four meters below the edge,” he said. “And if it’s dry next year, it’s going on like that.”

The water eventually fell below the edge of Lake Tahoe toward the end of the 2012-17 drought, which was followed by the region’s wettest year ever, Schladow said. These fluctuations from dry to wet are nothing new.

“What is changing is that these periods of extremely low and extremely high water seem to be happening more and more often,” he said.

It happens as climate change causes droughts to become drier, warmer and longer, and rainfall becomes shorter and more intense, he said.

“One of the manifestations of climate change that all models seem to agree on is that there will be more extremes,” he said. “Hot and cold, wet and dry.”

Low water levels in a major tributary of Lake Tahoe forced the U.S. Forest Service to cancel an annual festival celebrating the fall of the Kokanee salmon. The salmon are not expected to spawn in Taylor Creek this year due to the ongoing drought, though they could return in the coming years if conditions allow, the Forest Service said.

It is possible that as the water level continues to fall, the streams running into Lake Tahoe could be blocked by sandpits, which would further jeopardize the salmon’s ability to navigate them, Schladow said. Although they will spawn elsewhere, they are likely to have low success, he said.

So-called terminal bodies of water, which permanently lose their outflows and are cut off from tributaries, are known to grow salty and inhospitable to aquatic organisms, although it is not expected to happen with Tahoe soon.

Several inches of snow fell in Lake Tahoe this week, but it was not enough to make a measurable difference in water levels. The National Weather Service said more are on the way Sunday through Monday, with 3 to 6 inches expected to fall above 7,000 feet.

Another storm is expected next weekend, said Amanda Young, a meteorologist at the National Weather Service in Reno.

But overall, she said this year has been drier and warmer than usual in the forecast area.

And long-term forecasts require that these conditions persist, Schladow said, though he said that could change.

If the area sees significant rainfall, particularly rain, it will give rise to yet another concern: dirt is flowing in recent incineration areas, including watersheds at the southern end of the lake, which were scorched by the Caldor fire earlier this year.

“Next spring, a lot of material could be washed in from Trout Creek and the Upper Truckee River,” Schladow said.