The raging wildfire that is encroaching upon Lake Tahoe threatens to mar the pristine alpine lake that draws approximately 15 million visitors a year to its cobalt waters and sandy beaches, remote mountain trails and world-class ski resorts.
The Caldor Fire in California grew to more than 191,000 acres Tuesday, prompting the evacuation of 22,000 residents in South Lake Tahoe and the partial shutdown of casinos next door in Stateline, Nevada.
Beyond the immediate concern for public safety and the thousands of homes at risk is the threat fire poses to the clarity of and scenery around the world-renowned lake.
While wildfires have wreaked devastation across the West in recent years, it’s hard to imagine a more unsettling scenario than fire bearing down on Lake Tahoe, which Mark Twain described as “the fairest picture the whole earth affords.”
The lake straddles the California-Nevada line high in the Sierra Nevada. The top end is about 35 miles south of Reno and the lower end, which the fire is threatening, is about 100 miles east of Sacramento.
“Lake Tahoe is one of the more unique gems of lakes on the planet,” said Sudeep Chandra, a biology professor and director of the Global Water Center at the University of Nevada, Reno.
At more than 1,600 feet deep it is among the largest lakes in the country. Tahoe is about 22 miles long with more than 70 miles of shore, some of which is undeveloped and protected for outdoor recreation, and some of which is tightly packed with housing, gift shops and towering hotel casinos.
“It has a very high transparency,” Chandra said of the famed waters. “You can see almost 100 feet below the surface. It is one of the deepest lakes in the world. From a cultural viewpoint, it is important for the native peoples. The Washoe Tribe lived in the basin. And now it is important for recreation and the local economy.”
A fire burning to the shores of the lake threatens that famous clarity.
South Lake Tahoe, a California city on the south shore, is the most populous area within the basin, and is the area the Caldor Fire is encroaching upon as it moves northward.
Tahoe is known for year-round activities.
The Nevada side attracts people with its casinos. The four on the south end of the lake — Harrah’s Lake Tahoe, Harvey’s, Hard Rock Lake Tahoe and Montbleu Casino Resort — were limiting gambling Monday, with evacuation orders just across the state line in neighboring South Lake Tahoe and many workers needing to tend to affairs at home.
Caldor Fire updates:Highway 50 packed as thousands flee South Lake Tahoe
Warmer months bring throngs of people seeking Tahoe’s beaches, hiking and biking trails, boating and a variety of water sports such as kayaking and paddle boarding. Among the areas evacuated Monday were the famed Emerald Bay as well as the Tahoe Keys Marina.
Winter brings travelers seeking deep snow at about a dozen ski resorts around the lake, some of which offer views of the deep blue water from the slopes.
Already the flames have enveloped hillsides around Sierra-at-Tahoe Resort. Webcam footage appeared to show firefighters using a lift at Kirkwood Mountain Resort in their fight to keep the flames at bay.
Heavenly Ski Resort straddles the state line, with lifts and trails in both states. Monday’s evacuation orders included the area around its California operations.
Fire comes during busy season
The end of summer is usually among the busiest tourism periods for Lake Tahoe, and tourism is the key industry for the region.
The entire lake basin’s annual economy is estimated at $5 billion, with visitor services making up about 62% of that, said Carol Chaplin, president and CEO of the Lake Tahoe Visitors Authority.
But occupancy for Tahoe-area hotels already fell to below 30% in the past week because smoke from the fires drove visitors away. That was before officials asked travelers to avoid the area.
Now many hotels either are housing evacuees or emergency workers in town because of the fire, Chaplin said.
Normally hotels would be between 80-90% full this time of year heading into Labor Day.
Tahoe attracts most visitors from the San Francisco Bay Area, but increasingly sees visitors from across the United States and, prior to COVID-19 travel restrictions, international markets.
“We are an international destination,” said Chaplin, who also is a trustee of the Reno-Tahoe International Airport. “Our largest (international) markets are the United Kingdom, Australia, but we were starting to see India, China, South America.”
Tahoe was more popular than usual amid the COVID-19 pandemic the past two summers, even with limited international travel.
“We didn’t feel that because of the additional interest in outdoor recreation areas during COVID,” Chaplin said, adding that lodging and the airport have operated above 2019 levels during the pandemic. “People are really getting out there and using the trails like never before.”
Chaplin said her immediate thoughts were with people who already had lost homes to the fire, as well as those still in the fire’s path. But the long-term impact to the travel industry and all the people it employs also gives her concern.
Choking on smoke:South Lake Tahoe, usually bustling now, is empty
Many travelers to Lake Tahoe from California drive from Sacramento on U.S. 50, several miles of which were overrun by the Caldor Fire.
“The approach will be different,” Chaplin said of road trips to the area once the fire is under control. “It will be a challenge to come back from this.”
Water clarity makes lake famous
Tahoe is known for its clarity, with Twain writing in his 1872 book “Roughing It” that drifting on the lake in a rowboat was akin to floating from a balloon because the water was so transparent.
And while development and pollution have clouded the water somewhat since that time, the lake is still clear enough to see to depths of more than 62 feet on average, according to the latest report from the Tahoe Regional Planning Agency, which monitors environmental quality in the basin. The best measurements taken last year afforded 80 feet of visibility.
“It is really a national treasure,” said Sean McKenna, executive director of the Division of Hydrologic Sciences at the Desert Research Institute in Reno. “It has stayed that way through a very concerted effort and management practices.”
Maintaining the lake’s clarity has been a concern since the 1960s, and the municipalities around the lake have taken extra precautions, such as pumping all of their wastewater outside of the lake’s basin for treatment, to ensure the water stays clear, he said.
The Tahoe Regional Planning Agency also enforces a variety of restrictions on development, often to the chagrin of home owners and developers, with the intent on keeping runoff out of the lake and maintaining Tahoe’s clarity.
The focus lately is on storm water entering the lake, carrying with it sediment and nutrients that can affect lake clarity.
“Something we worry about a lot is the post-fire hydrologic effects,” McKenna said. “The soils become less permeable, so that could lead to more runoff and debris flows, more sediment. A severe fire going through there will change all the year-round activities significantly.”
What researchers don’t know is whether the effects will last for a short term or continue for years.
In 2007, the Angora Fire burned just over 3,000 acres in the Tahoe basin, destroying 254 homes. That fire’s impacts on the watershed were studied and found to be minimal.
“It is safe to say it is not an easy fix and will take resources and energy above and beyond what we have contributed to restoration to date,” Chandra said.
Ecologically speaking, Tahoe was home to Lahontan cutthroat trout, which wildlife officials are reintroducing to waterways in the region, and remains home to 10 endemic invertebrates, Chandra said.
The smoke from wildfires alone, which have been hammering the region for weeks, can affect the lake by “reorganizing” fisheries and aquatic plants, Chandra said.
But the other concern is that a wildfire in the basin will leave a burn scar, allowing more runoff into the lake that can bring more nutrients and soil, clouding the water and providing nutrients for algae that can further affect the clarity.
“While these are challenging times certainly for the people of Lake Tahoe, the lake also has had the remarkable ability to recover over time,” Chandra said, citing deforestation in the 1800s that increased sediment in the lake.
That problem was largely resolved by the 1950s when the forest had regrown, he said.
“We are facing the same situation today, a catastrophic and in this case unintended event is occurring that has the potential to change the long term clarity in the lake,” Chandra said.
“The science-supported management activities that we need to plan after this fire can help us understand the short- and long-term impacts to the lake’s fragile clarity and — where to go next.”
Follow Ryan Randazzo at @UtilityReporter.