Tahoe’s Fragile Beauty: The 5 greatest threats to Tahoe

A secchi disc is lowered into Lake Tahoe to measure lake clarity. | UC Davis Tahoe Environmental Research Center

Tahoe is majestic and awe inspiring with its jagged mountain peaks, thick forests, swift-running rivers and hundreds of glacial and alpine lakes. Winters can be harsh. Spring yields to a wondrous array of wildflowers and new growth and during brief summer months, wildlife and plants thrive.

As a destination with more than 15 million visitors annually, Tahoe’s beauty and environment is delicate and under threat from climate change and invasive species. Protecting Lake Tahoe’s clarity is a chief concern, as is protecting the more than 290 animal and 1,000 plant species, including several endangered species. Then there’s the effects of climate change that has increased the risk of wildfires and reduced snowpack. These are among the five greatest threats to Tahoe’s fragile beauty.

(1) Lake clarity
Pollution is affecting lake clarity from litter, fine sediment, nutrients, oil, grease, microplastics and pathogens. Nutrients such as phosphorus and nitrogen fertilizer support the growth of free-floating and attached algae. Plastic bags filled with dog poop left on the trail wreak havoc on the environment and lake clarity.

“Clarity right now has leveled out. Clarity used to be 100 feet. It’s currently leveled out at about 65 feet or so,” says Heather Segale, education and outreach director of UC Davis Tahoe Environmental Research Center (TERC). The annual State of the Lake Report released on July 6 reports the average clarity of Lake Tahoe was at 61 feet in 2021, a 2-foot drop from the previous year.

“There are more aquatic invasive weeds, algae growing on the rocks and we are seeing more algal blooms,” says Amy Berry, executive director of Tahoe Fund. “Due to warming temperatures, climate change, less snowpack and less cold water running into Lake Tahoe, we will see real impacts that will be noticeable, especially where we access the lake.”

(2) Aquatic invasive species
The native food web and the impact of aquatic invasive species are of concern for Segale.

Segale explains that the nonnative largemouth bass, bluegill and lake trout have impacted the native species over time.

“Some of the species such as the Lahontan redside shiners, speckled dace, the Tahoe sucker, tui chub and the mountain whitefish are some of the fish we don’t see or hear much about these days. The lake trout have outcompeted the Lahontan cutthroat trout. They are all competing for the same food,” she says.

Lahontan cutthroat is the only trout species native to Lake Tahoe. However, by 1930 they had almost completely disappeared. Each year, U.S. Fish & Wildlife Service, Lahontan National Fish Hatchery Complex, in Gardnerville, Nev., stocks about 100,000 catchable Lahontan cutthroat trout in Lake Tahoe. About 20 percent of the trout is tagged to help biologists evaluate the success of the stocking effort along with the growth, survival and distribution of the fish. Read more about one of the region’s only remaining Lahontan cutthroat populations in our story on Independence Lake in this edition.

Other invasive species threatening Lake Tahoe include Asian clams, Eurasian watermilfoil and curly-leaf pondweed.

(3) Endangered, threatened or rare
On a snowshoe tour last winter at Sugar Pine Point State Park, Sarah Hockensmith, outreach director for Tahoe Institute for Natural Science, pointed down to a snow-covered area and explained that beneath it lives the Tahoe yellow cress, which emerges in the spring. The plant is considered endangered and only grows on the shores of Lake Tahoe.

The mountain yellow-legged frog is also on the endangered list of species. The frogs are threatened by other prey, the introduction of nonnative fishes, disease, pesticides, environmental changes from drought, warming temperatures and habitat loss.

“They found some mountain yellow-legged frogs down on the West Shore. Amphibians are a concern overall,” says Segale.

Segale also worries about the human impact on Tahoe’s black bears.

“I worry about the bears in general because of trash and people being careless,” says Segale. Tahoe is bear country. Leaving cars unlocked with food in the vehicle, leaving homes unlocked for bears to forage in and not disposing of trash properly can create a bear encounter and can ultimately cause a bear to be euthanized.

(4) Climate change
Climate change is a concern to both Segale and Berry with an epidemic of unhealthy forests and high wildfire danger at the top of the list. Climate change affects Tahoe’s weather, creating drought, a lack of snow and lessened lake clarity. Climate change alters the life cycles of plants and animals. Results of warming temperatures include loss of habitats, changing hibernation patterns and plant life emerging and blooming earlier in the spring.

“If I were to dig into climate-change impacts, I am worried about the obvious things: fire, forest health, fire impacts, smoke and everything that goes along with that,” says Segale.

Berry echoes the fire concern, as well.

“We are living in a forest that’s incredibly unhealthy. The biggest issue is we have an overgrown forest that hasn’t had a lot of fire on it. There’s a lot of fuel underbrush and there are too many trees. We need to reduce the number of trees,” says Berry, who adds that a majority of all wildfires are caused by humans.

Segale also points to the loss of snowpack due to climate change that threatens Tahoe and the winter recreation industry that depends on snow.

“All of our models show what will happen in Tahoe in the winter. We’ll see less desirable snow conditions, fewer days of freezing, decreasing snowpack, snowline rising to higher elevations and more weather extremes. We saw that this winter,” says Segale.

TERC released the Save Our Snow Instagram filter in the winter to highlight the declining snowpack.

(5) The Watershed
The lessening snowpack is also a threat to Lake Tahoe’s watershed, which provides critical wildlife habitat and is imperative during droughts. A healthy watershed also helps to reduce fire danger.

Every snowflake and drop of rain that falls in the mountains surrounding Lake Tahoe contribute to the watershed. When snow melts, it flows into Lake Tahoe through 63 creeks, streams and rivers.

As the snowpack dwindles, so does the ability of the watershed to protect plant and animal species and to protect the region from fire danger.

The Truckee River, Lake Tahoe’s only outlet, flows from Tahoe City down through Reno and eventually into Pyramid Lake, providing drinking water to downstream users in Northern Nevada. This water supply is also threatened by a declining snowpack.

What’s being done?
Berry says that one of the ways to effect change is continued education and awareness. The Tahoe Fund is also working with public agencies to deal with forest health, including partnering with U.S. Forest Service and Tahoe Regional Planning Agency to remove 17 acres of invasive plants in the Taylor and Tallac creeks and marshes. It is the largest aquatic invasive species project to date in the Tahoe Basin.

What can you do?

Reduce carbon emissions
According to Segale, reducing one’s carbon emissions by 1 ton per year would make a difference in climate change and in supporting Tahoe’s snowpack. Simple things like turning off the lights, turning down the household thermostat in the winter, reducing meat consumption and eliminating single-use to-go containers. Take the Carbon Reduction Challenge on TERC’s website to learn more.

Tread lightly
When in the forests, stay on the trails, practice trail etiquette and pack out everything, including dog poop.

Leave no trace
Pack out all trash, leftover food and waste. Leave nature as it is; don’t pick flowers. Leave the environment pristine and respect wildlife.

Clean, drain and dry
Clean, drain and dry all boats, paddleboards, kayaks, canoes, paddles and gear before entering a body of water to mitigate the spread of aquatic invasive species.

There are several organizations that welcome volunteers to help to protect Tahoe’s environment. Sign up for a beach clean-up, help maintain and clean trails or help remove invasive weeds. The League to Save Lake Tahoe, Clean Up the Lake, Foriver-Truckee River Watershed Council, U.S. Forest Service and Truckee Litter Corps are just a few organizations that could use help.