Yosemite National Park officials are issuing a chilling warning to spring travelers: The park’s breathtaking waterfalls and scenic rivers are currently death traps.
The alert follows a heartbreaking tragedy in early April, where a five-year-old boy drowned at Shasta Lake after falling into frigid waters without a life jacket.
It was a “sobering reminder,” according to the Shasta County Sheriff’s Office, of how a sunny family outing can turn fatal in a heartbeat.
While the California sun might be heating up, the water is doing the exact opposite. As the Sierra Nevada snow pack melts, it sends a torrent of icy runoff screaming down thousands of feet into the Merced River and surrounding creeks.
Experts warn that beauty hides a physiological nightmare called “cold shock.”
“Sudden immersion in cold water can stimulate the ‘gasp reflex,’ causing an involuntary inhalation of air or water and can start the drowning process immediately,” the California Governor’s Office of Emergency Services warned.
The math of the melt is brutal, with breathing being impacted if you’re in water below 77 degrees Fahrenheit. Breathing becomes nearly impossible to control in water that is between 60 and 70 degrees, and muscle control vanishes with minutes if you find yourself in water temperature that is between 50 and 60 degrees, according to experts.
“Right now, every stream in Yosemite is running fast, high, and cold,” park officials wrote on Instagram.
“Submerging in water this icy (40°F or 4°C) can almost immediately send you into cold shock,” they added.
It’s not just swimmers who are at risk. The Yosemite Search and Rescue team performs between 15 and 20 rescues every year for people who never even intended to get wet.
“Most accidents happen when people get too close to the water to take photos, play on rocks, or take a quick dip to cool off,” officials said.
The granite boulders surrounding the falls–even the ones that look dry–are polished to a “treacherous” slickness by years of mist and spray.
One slip can send a hiker into currents that look calm on the surface but are surging with violent power underneath.
If you’re heading to the valley soon, experts have a few tips to keep in mind: stay back from edges, don’t leave kids alone, and if you do fall in, flip onto your back with your feet pointed downstream.
