A flash flood in Havasu Canyon leads to bad decision making by campers due to cognitive bias

search and rescue helicopter bad decision making havasu canyon flash flood
A Search and Rescue helicopter getting ready to pick up campers cut off from the flash flood the night before.Michael Deeter
Signs Were Ignored

We hiked into Havasu Canyon on an early mid-August morning under clear skies and a warm Arizona sun. The trail winds down several sets of switchbacks from the trailhead to the canyon floor. From there it is an easy eight miles to Supai Village, where the Havasupai Tribe has lived for over a thousand years. The village itself is in a remote section of the canyon, so much so that they still receive mail via a pony express-like mule train.

A short hike from the village takes you to the famous Havasupai Falls and the campground below. The campground itself is bisected by a stream that runs from the falls and snakes its way beyond and on down to the Colorado River. The entirety of the stream, even below the falls, is famous for its crystal clear turquoise waters. That day, though, the stream became cloudy in the late morning shortly after we established our camp on the far side of the stream. 

Water levels began to rise as we finished lunch, at which point a Ranger from the Bureau of Indian Affairs advised campers in our area to expect flash flooding. The decision to move to higher ground was obvious, but everyone in the area didn’t agree. Several groups we talked to had been to Havasu Canyon before under similar circumstances, seen monsoons come and go, and had never been in a flood. We wished those people luck before packing up and moving camp across the stream to higher elevation.

Pickings were slim up high and what remained was a less than ideal spot situated near some well used outhouses, mule corrals, and a trash drop off. Tents were pitched just as the once distant monsoons moved overhead forcing us to take shelter. A few hours later the nights silence was broken by what sounded like a freight train moving through the camp, followed by screams below. We emerged from our tents to find chaos in the lower campground. Shouting had replaced the sound made by the storm surge and lit headlamps began to fill the once dark spaces.  

The flood many believed wouldn’t come had hit, and hard. The once tranquil stream was now a deluge flowing at full force, its banks had swelled to the point of overtaking the campground and cutting off several groups below, including the campers who had chosen to stay across the stream. We helped who we could, most still in their tents struggling to get out against the raging currents. For many, though, the flood waters had cut them off and any attempt at rescue would likely have been disastrous, if not fatal.  

bad decision making flash flood havasu creek wilderness medicine magazine
Havasu Creek, once a brilliant crystalline blue now turning a muddy brown as the banks begin to swell.Michael Deeter
Cognitive Bias and Decision Making

My first thoughts were of those who had chosen to stay on the far side of the stream. I couldn’t help but question, with all the information they had on hand, why they chose to stay instead of head to safety. It wasn’t until years later I learned about cognitive bias and how it is that one bad decision can cascade into a series of bad events, potentially leading to a catastrophic outcome. Deep in our subconscious we are hardwired to use mental shortcuts, also called heuristics, to make complex decisions based on the limited information available at the time. Somewhere along the evolutionary chain our caveman ancestors started using heuristics to stay alive. 

In the early ‘90s Charlie Munger, the executive vice chairman of Berkshire Hathaway, gave a series of talks in which describes 25 heuristics he believes to be the root of human’s bad decision making. In his discussions he explained that by being cognizant of the decision making process, and how heuristics work, one can be armed against making bad decisions.  While the 25 described have far reaching applications, three relate directly to backcountry travelers.

The first is what he calls the Doubt-Avoidance Tendency. Doubt, if left unchecked, can be mentally crippling. By suppressing doubt our cave man ancestors were able to make split second decisions while in fight or flight mode to avoid being eaten. When time is in short supply, and a decision needs to be made quickly, removing self-doubt from the equation enables us to make a quicker, albeit hasty, decision. 

Next, Inconsistency-Avoidance Tendency is the inclination to make decisions based on what we have done, or what has worked, in the past, without analyzing the information in our current situation. In order to conserve precious cognitive space our brains have evolved to rely on this tendency to speed up our decision making process. Coupled with doubt-avoidance tendency, our minds can be hard wired to make poor decisions based off past actions that may not have any correlation to the situation in which we find ourselves in.

Finally, Excessive Self-Regard Tendency is a propensity to overestimate our abilities or overvalue the decisions we make. After several trips in the backcountry it is common to develop confidence in our abilities. Sometimes we are placed in situations where we overestimate our abilities, and this is where excessive self-regard presents itself. Combining this with the tendencies to avoid doubt and inconsistency stacks the deck against us.

Take those campers on the far side of the river. Their overconfidence in the decision to stay put based on previous monsoons led them to Inconsistency-Avoidance even though they had ample information screaming it was a bad idea. The tendency to avoid doubt, coupled with excessive self-regard, worked together to reinforce a potentially catastrophic decision. Had they been more objective about the situation and looked at their decision from other perspectives it is likely they would have relocated with us up on high ground.

bad decision making flash flood havasu canyon arizona
The author, second from the right, sits with three people on the ledge overlooking the destruction below.Michael Deeter

The topography of the canyon was forever changed that night. Unbeknownst to us at the time, the storms had caused a breach in an earthen dam far up stream unleashing the waters it had held back for rancher’s livestock. The resultant surge rerouted the course of the stream, bypassing Navajo Falls, a popular spot for cliff jumping. The village center was spared, but the surrounding homes were not as fortunate. Many were damaged beyond repair, others lost livestock vital to survival in the remote Arizona canyon. The trail out of the canyon was washed out and impassable. 

FEMA, local Search and Rescue teams, and The National Guard were called in to coordinate and assist with rescuing the campers who were unable to reach safety after the floods had hit. Had people made better decisions, though, rescue efforts would not have been necessary and vital resources could have been put to use assisting the villagers in recovering their homes and livelihood after the incident. Rescuers were also risking their own safety extracting campers below the falls. Situational awareness coupled with insight into cognitive bias’s effect on the decision making process are tools that should never be neglected in the backcountry.

Luckily by the end of the day everyone had been accounted for, and all were helicoptered to the trailhead by National Guard Blackhawks.

MIKE DEETER lives in Northern Colorado with his family where he works as a physician assistant. When he isn’t working he enjoys spending time in the backcountry, photographing, and writing.

This article originally appeared in Wilderness Medicine Magazine.