Poisonings from deadly mushrooms are on the rise in Lake Tahoe

From foraging-focused Facebook pages to mycological societies to even area hospitals, everyone agrees: Poisonous mushrooms are a threat to anyone finding their own fungi in Lake Tahoe. While multiple mushrooms are to blame, one is already known to be a problem throughout California: Amanita phalloides, or the fatal “death cap mushroom.” It’s already been found in the Sierra foothills, raising concerns that it could be encroaching into higher elevations. 

The poisonous compounds found in death cap mushrooms are responsible for more than 90% of the world’s annual mushroom poisonings, with a death rate of around 22% to 30% for those who receive medical care. Symptoms start hours after ingestion and usually present as stomach pain, nausea and vomiting, before progressing to liver and kidney failure, brain swelling, coma, and even death. It often has a latency period between initial symptoms and severe symptoms, which can mislead patients into thinking they’re fine. Even patients who recover can suffer from permanent liver damage.  

Unfortunately, death cap mushrooms likely aren’t going anywhere anytime soon. 

“Death caps, in particular, have been noted as a species that is expanding its range,” says Jim Adams, president of the Sacramento Area Mushroomers, an organization affiliated with the North American Mycological Society. “In the Bay Area, death caps are displacing chanterelle mushrooms under oak trees. So what could be happening in the Sierra is that same movement of mushrooms starting to expand.” 

Adams has been foraging since the late 1990s and says he’s seen quite a lot of change over his mushrooming career, especially around who is out foraging. “In Tahoe, the community has changed, and people from different areas are coming in and working remotely,” he says. “And maybe some of those people are able to get out in the outdoors a little more than some of the working-class people who got kicked out.”

He points to that change in foragers to at least partially explain the increase in anecdotal reports of deadly mushroom sightings and poisonings, which Barton Health reports it has seen increasing in its South Lake Tahoe emergency room. He thinks the increased interest in mushrooming as a hobby since COVID-19, combined with the general lack of a mushroom-hunting culture or organization in Tahoe, has led to more people eating more types of mushrooms. 

Adams estimates that in the Tahoe area, there are probably a few dozen “choice edibles” — mushrooms that aren’t just edible but also tasty — that are hard to confuse with poisonous mushrooms. These include well-known species like morels and slippery jacks. But other mushrooms can be a lot trickier to identify. He points to those in the genus Aminata, some of which can look like grocery store portobello mushrooms. “With those, the difference between a poisonous species and a choice species can be as subtle as whether there’s a bulbous swelling on the stalk underground.”

While there’s yet to be any scientific confirmation of the death cap mushroom growing in the Tahoe Basin proper, it is known to be an adaptable and invasive species. The fungus was likely accidentally introduced to California in the 1930s but has only recently been spotted in mountain towns in the American West. It has a symbiotic relationship with trees, usually found near the trunks of live oaks around the Sierra foothills. But reports of the poisonous mushroom are popping up more and more on citizen science programs like iNaturalist, as well as with anecdotal evidence from Tahoe area mushrooming groups. 

It’s possible the deadly mushrooms could be spread unintentionally by people trying to cultivate mushrooms and accidentally releasing spores, Adams says, or their spread could be a factor of climate change. “It’s getting warmer. It’s changing rain patterns,” Adams says. “Mushroom-hunting patterns are moving into November, rather than October. So that changes what mushrooms and what trees can grow and when.” 

Though death caps were first found on oak trees, according to the Bay Area Mycological Society, they’ve recently been found on tanoaks around Mendocino and pine trees around Marin County. Given those adaptations, it’s possible they may be able to adapt to Tahoe’s native trees — especially since researchers have already documented the death cap growing on new tree species. While the Tahoe Basin doesn’t have live oak trees, it does have black oaks and huckleberry oak, both closely related to live oaks. In social media groups, local foragers have anecdotally reported finding the death cap (and other poisonous mushrooms) near Lake Tahoe. 

While the death cap is the most well-known deadly mushroom found around the Sierra, it’s not the only poisonous one, nor does it even have the most ominous-sounding name. The western destroying angel, or Amanita ocreata, is also prevalent throughout California. It’s a native species and one of the most deadly in the state. It’s been spotted by amateur foragers just east of Desolation Wilderness in Eldorado National Forest, near Emigrant Gap in Tahoe National Forest, near Sierraville north of Truckee, and in Nevada City, in the Sierra foothills.

In addition to death caps and western destroying angels, South Lake Tahoe’s Barton Health warned on Oct. 11 of another poisonous mushroom sprouting in Tahoe: Amanita muscaria, known as the “Super Mario mushroom” for its distinctive red cap with white spots. It’s the cause of the uptick in mushroom poisonings in the Barton Health emergency room. So far, no one has died in Tahoe from eating Amanita muscaria. But the hospital warned that the mushroom’s bright colors can be attractive to children, and Adams thinks there’s a reason it may appeal to adults: “People often eat Amanita muscaria because they think it will be hallucinogenic,” he says.

When it comes to psychologically active mushrooms, the Sierra Nevada does have a few. But mushrooms containing psilocin (commonly called “magic mushrooms”) are harder to find and generally grow in some unpredictable places. They’ve been reported via iNaturalist in Plumas and Eldorado national forests but are dangerous to look for, Adams says, as they’re not the type of magic mushroom one generally wants to be eating. He says he knows several people who have eaten the “Super Mario” mushrooms, known to have hallucinogenic properties, and regretted the general unpleasantness and discomfort that went with the experience. 

According to Adams, it’s better to just stay away from trying to find anything in the Amanita or Psilocybe genus, given the high consequences of misidentifications. “There are many easier, better ways to change your perception, if that’s what you’re looking to do,” he says. 

Further complicating mushroom foraging in Tahoe is the fact that there’s no official database or organization in the region charged with identifying or reporting new species. While iNaturalist is a widely used tool, it relies on citizen science, rather than expert knowledge. Adams recommends foragers reach out to the local mycological society whenever they have identification questions. He’s enthused that more people are interested in mushrooming than ever before but knows that comes at a cost. “The level of expertise that you see in people doing mushroom hunting has decreased significantly,” he says. “More people with less knowledge about what they’re doing.”

With some basic knowledge, it’s easy to stay away from mushrooms that can cause sickness. Mushrooms in other genera, like Gomphus mushrooms, are safer for beginner foragers. Gomphus mushrooms look similar to chanterelle mushrooms, but if misidentified, they won’t kill you. “That one isn’t deadly poisonous,” Adams says. “It would just maybe give you the runs or a round of vomiting.” 

Adams advises that beginner foragers join their local mycological society and stick to easily identifiable genera, like the Boletus genus, with species like king bolete. As long as you’ve gone out a few times with an experienced mushroom hunter and memorized a few basic characteristics, Adams advises, you’ll likely be OK. “It’s really impossible to confuse it with something that could poison you,” he says of the porcini mushroom. “But it’s when you find people out there that don’t know what they’re doing that they poison themselves or their friends.”