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If you visit Lake Tahoe this summer, the beaches might seem a little smaller than they were a few years ago.
It’s not an optical illusion. Large sections of them really are underwater.
Dozens of feet of snow that blanked the Sierra Nevada this winter, generated by blizzards from raging atmospheric river storms, have been steadily melting all spring and summer, sending billions of gallons of water rushing downhill and steadily raising the water level at Lake Tahoe.
Sometime, probably this weekend depending on the exact temperature, the lake’s level will reach its maximum legal limit — 6,229.1 feet above sea level — a point that federal officials maintain by releasing water from the gates of the lake’s only dam — the 18-foot-high Tahoe Dam, near Tahoe City — into the Truckee River. On Friday, the lake was less than an inch from that peak level and still rising.
The surface of Lake Tahoe, which stretches 22 miles long, has risen an astounding 8 feet since the beginning of 2016, when it hit a low point during California’s historic 5-year drought.
Put in perspective, all the extra water in the lake now that wasn’t there three years ago is roughly 1 million acre-feet, or 313 billion gallons — enough water to meet the needs of 5 million people for a year. Lake Tahoe’s rise over the past three years is the same as if Hetch Hetchy Reservoir, the main water supply for San Francisco, had been emptied into it nearly three times.
In other words, Tahoe is full. Right to the top.
“Standing on the shoreline, it’s a huge difference,” said Dave Wathen, deputy water master for Lake Tahoe. “There were big beaches at lower water levels. Sand Harbor Beach near Incline Village is a very big beach. A lot of people could fit on it. Now, it’s tighter. It’s drastically different.”
Higher water not only means smaller beaches but higher boat docks and, in some places, shoreline erosion. It also means ample water supplies for towns around the lake, cities such as Reno, and farmers from Reno to Fallon, Nevada, all of whom depend on Lake Tahoe every year for irrigation and drinking water.
This summer will be the third time in the last three years that the lake has come right up to the edge of its legal limit. The last times that happened were 20 years ago, in 1998, 1999 and 2000.
California’s drought was broken by enormous storms in 2017 that caused flooding in downtown San Jose, wrecked the spillway at Oroville Dam and dumped so much snow that some Tahoe-area ski resorts had to close for days to dig out their chairlifts.
From New Year’s Day until the summer of 2017, the lake rose more than 6 feet, the most ever recorded in more than 100 years. When 2018 rolled around, the snowfall was a little below normal, but higher lake levels from the year before allowed the melting snow to fill it again to the top. Now with this year’s big winter Sierra snowpack, which was 162 percent of the historic average on April 1, Tahoe is in great shape, experts say.
The history behind Tahoe’ rise and fall is complex. After the level rose dramatically in 1907 following a big winter, causing flooding, property owners, farmers, ranchers, the local utility company and other powerful interests battled in court over water rights and how to control the lake’s height.
A 1935 legal settlement set the maximum level at 6,229.1 feet and doled out water rights and rules. The settlement is administered by two federal water masters in Reno, who monitor the lake’s level multiple times a day. Although 63 creeks and streams flow into Tahoe, it has only one outlet, the Truckee River, where the 109-foot-long concrete Tahoe Dam, built in 1913 with 17 gates, is listed on the National Register of Historic Places.
It’s not just depth. The lake’s famed clarity increased 10 feet from 2017 to 2018, according to an annual report released by UC Davis scientists in May.
The jump was the largest annual improvement in 50 years, since measurements at the iconic Sierra Nevada lake began in 1968.
On average in 2018, the study found, a 10-inch white disk lowered from a research boat was visible 70.9 feet below the water’s surface. A year before, the disk could be seen only up to 60.4 feet, the lowest visibility level ever recorded.
The reason for the huge loss of clarity in 2017, scientists said Thursday, was that heavy rains in the winter of 2016-17 washed massive amounts of sand and mud that had built up during the drought into the lake. In fact, more sediment washed into the lake in 2017 than the previous five years combined. The big drop-off in clarity alarmed environmental groups, tourism leaders and many Tahoe lovers.
In 2018, however, following a relatively mild winter, not as much sediment washed in, returning the lake to a more normal pattern and boosting visibility.
Overall, the lake still has a long way to go to recover the level of clarity it had half a century ago. In 1968, Tahoe’s visibility was 102.4 feet but declined due to erosion from construction, fertilizer from golf courses and loss of wetlands that filter pollutants and other human disruptions.
During the past 20 years, the state, federal and local governments have spent hundreds of millions of dollars restoring wetlands, tightening building rules and making other changes to try and stop the 1,645-foot deep lake — America’s second-deepest, behind Crater Lake — from becoming a muddy green mess of algae and silt.
That work, highlighted in “Keep Tahoe Blue” bumper stickers, has shown slow but steady progress.
The five-year average in lake visibility — widely considered an indicator of the Lake Tahoe basin’s environmental health — is now 70.3 feet, an increase of almost a foot from the previous five-year average.
And while the beaches might be smaller, there are plenty of places to tie up your power boat.
“During the drought, you’d look down at the end of a dock, and you’d see sand because the water had receded so far,” said Geoff Schladow, a professor of civil and environmental engineering at UC Davis who directs UC’s Tahoe Environmental Research Center.
“You couldn’t put a boat in some places. Now the docks all have plenty of water around them.”