The Cold Truth About Drowning in Colorado

Park rangers spent a week looking for a body in Cherry Creek Reservoir.
Park rangers spent a week looking for a body in Cherry Creek Reservoir. Colorado Parks and Wildlife
The surprise plunge into cold water makes you gasp — and now you have one minute to live.

You’re a fit, strong, swimmer enjoying a Fourth of July outing on a Colorado lake when you accidentally fall off the boat. You had a life vest on board, but you thought that as a grownup you didn’t need to wear it whenever you are on the water. Now as you fall, you reach for the life jacket but can’t put it on before you hit the waves. You gasp – everyone inhales when they hit cold water unexpectedly. Momentum forces your head under the surface. Less than a cup of water fills your lungs. And just that fast, you’re dying.

You're a victim of Cold Water Immersion Shock, a phenomenon that Colorado researchers now say can occur in water as warm as 60 to 70 degrees Fahrenheit.

That’s a change: In the past, experts said that water needed to be 50 degrees Fahrenheit or lower before cold-water shock occurred. But a 2019 study, done by two researchers from the UC Health Medical Center of the Rockies in Loveland, suggests that cold-water shock happens in much warmer water, too.

Cold Water Immersion Shock is different from the more familiar hypothermia (which also occurs on land) and happens much faster. Cold-water shock comes almost instantly, causing death in less than one minute. Hypothermia takes a few minutes to kill; if you can keep your head above the water for a crucial sixty seconds, then you may have ten minutes before the cold renders you unable to move your leg or arm muscles, or even shout for help. A life vest just shifts your chances, to paraphrase the Hunger Games books and movies, so the odds are forever in your favor.

The wicked shock of a surprise fall into a cold lake or stream is utterly unlike diving into a swimming pool or even participating in cold-water therapy. In those other, controlled instances, you know the cold is coming, so you can take a breath and hold it before your body enters the water. But cold-water shock almost instantly fills a victim’s lungs or makes the throat slam shut — in some cases, it also triggers heart attacks, even in healthy people.

Back on the boat, your surprised friends don’t realize that you’re in imminent danger. Your death doesn’t look at all like how TV and the movies portray a drowning. For one thing, you can’t call for help — because your lungs are full of water or your throat is shut. For another, your weakening arms can’t break the surface to wave for assistance. You just quietly slip beneath the surface.

Colorado is on pace to exceed its tragic 2020 record, when 34 people drowned in the state, according to Colorado Parks and Wildlife, the agency that manages many of Colorado’s lakes and rivers. After a slight improvement in 2021’s numbers, water-related deaths have already jumped this year. “We don’t know exactly why the drowning numbers went up again,” says CPW spokesman Joey Livingston. “It may just be that our population has increased.”

By June 22 of this year, thirteen people had drowned, CPW reports. Of those, eleven victims were not wearing a life vest/life jacket (formally called a Personal Floatation Device, or PFD). Two victims were wearing PFDs, but they drowned in river rapids where other risks abound, such as getting trapped by fallen trees.

According to current figures, at least 85 percent of drowning deaths in Colorado happen when the victims aren’t wearing a PFD. That statistic echoes national numbers: Up to 86 percent of drowning victims weren’t wearing a life preserver, according to the U.S. Coast Guard. Many times, life jackets were on board the boats but the victims couldn’t reach them or couldn’t put them on while in the water.

Colorado’s recreation rules require that children thirteen and under wear a PFD anytime they’re on the water. For adults, boats only need to have a life vest on board for each passenger and crew member; most states have similar rules. Colorado’s park rangers often tell boaters that adults should always wear a life jacket, Livingston says, “But usually people think that the problems won’t affect them, or that they’re strong enough swimmers.”

That’s what you believed until you fought for your life underwater...and lost.

Why do so many people die of cold-water shock in Colorado compared to, say, Florida or Alabama?

Primarily, it’s the water temperatures, explain David Farstad and Matthew Luttrell, who authored the 2019 study. The researchers reviewed unexplained drowning accident records for nearly a seventy-year period, from 1950 to 2018, focusing specifically on what are called “flush drownings,” in which victims didn’t hit their heads and weren’t trapped by rocks or logs. Farstad and Luttrell then compared accidents in the Rocky Mountains, where lakes and rivers are almost always chilly, to drownings in the U.S. Southeast, where rivers, in particular, are much warmer.

The records revealed that in the Rockies, more than 60 percent of victims were “flush drownings”; the victims didn’t hit their heads, didn’t have seizures, and didn’t get trapped by logs, rocks or other debris. The study's conclusion: Most drownings in Colorado and nearby states probably stem from cold-water shock. Several deaths happened in water temperatures of 60 degrees Fahrenheit, or even around 70 degrees. 

In mid-June, the surface temperature at Cherry Creek Reservoir registered about 54 degrees Fahrenheit.

Just before brain death, you recalled that an angler in a nearby boat wore a combination life vest/fishing vest. You saw a water skier wearing a basic life vest purchased at a discount retailer, too. You’d also spotted kayakers wearing specialized paddling PFDs that they’d bought at a sporting goods store. Before you left dock, you’d heard a sailboat skipper insist that everyone aboard that vessel had to wear an inflatable PFD, which automatically deploys when a person hits the water. All those people had found ways to stay cool while also wearing PFDs that meet U.S. Coast Guard recommendations for cold or moving water. By contrast, the floating cushion your friends tried to toss you is useless if a drowning victim can’t reach it.

Park rangers and other first responders recently spent a week on Cherry Creek Reservoir looking for, then retrieving, the body of a drowning victim who’d been riding a float tube behind a boat. The victim, like so many others, was an adult who wasn’t wearing a PFD. “It’s the hardest part of the job,” Livingston says of the rangers who must tell a victim’s friends and families that their loved one has died, and that it could have been avoided.

But wait! After reading this story, you swallowed your pride and bought, borrowed or rented a PFD, then wore it (fully zipped up) all the time you were on the water. Then you fell overboard. Again, you gasped and inhaled with shock. But your life vest kept your head above water. Your brain re-engaged — you started swimming. Your startled friends pulled you back on board gently (to avoid causing you a delayed heart attack). They then wrapped you in warm layers to prevent hypothermia; like all good Coloradans, they carry extra clothes because they know about this state’s changeable weather.

And so, because you wore a simple, affordable life vest, your story ends not with your funeral, but with you having to suffer nothing worse than your friends’ good-natured joking.
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Penelope Purdy is an award-winning Colorado journalist and guidebook author, as well as a certified sailboat skipper and scuba diver. She also paddles open canoes and inflatable kayaks in moderate whitewater (Class II to Class III- rapids).