The Payson flash flood: How did this happen?

It happened in a flash.

A wall of black water mixed with fallen trees, ash and debris swept away 14 people Saturday, killing nine, at a swimming hole at Cold Springs near Payson.

The search for another person, Hector Miguel Garnica, continued with no success Monday and was to resume Tuesday.

Sgt. Dave Hornung of the Gila County Sheriff’s Office said finding Garnica alive would be a “miracle.”

As searchers and investigators worked through the day, questions persisted, beginning with, “How did this happen? And could it have been avoided?”

Officials said they are not sure exactly what led to the flood, but attention turned to an area upslope of the flood site, where a wildfire blackened 7,198 acres in June along the Highline Trail.

“We’re actually still trying to evaluate whether damage from Highline Fire contributed,” said Carrie Templin, a spokeswoman for Tonto National Forest.

After a wildfire

Wildfires leave scars. Some of the scars are obvious — blackened stumps, charred hillsides, fallen trees — but others remain hidden from view.

One such scar is the sudden inability of the forest to absorb rain and runoff.

A summer monsoon storm can trigger flash floods such as the one that swept through Ellison Creek on Saturday. Ordinarily, vegetation, both dead and alive, mitigates the effects of heavy rain. The forest floor, full of trees, brush, grass, roots and duff, absorbs water, so that it moves downhill slowly.

“Every time a raindrop falls, it’s hitting something,” said Ann Youberg of the U.S. Geological Survey.

Wildfire strips away brush and branches. Trees can be reduced to ash. Not only does that raindrop flow downhill without interference, it picks up speed.

“After fires, there’s nothing to stop that raindrop,” Youberg said. “There’s nothing to slow down that velocity.

“There’s nothing there that breaks the fall.”

The result can be what happened on Ellison Creek — a deadly wall of water filled with mud, ash, rocks and trees, the flotsam of nature swept downstream.

Flash floods can develop miles away and come with no warning — it’s possible to be hit by rushing water under clear skies. The wall of water that struck Saturday was said to have been 40 feet wide and 6 feet tall.

Andrew Taylor, a meteorologist with the National Weather Service, said radar forecasts for the area showed rainfall above the Highline Fire scar from a half-inch to an inch and a half.

Meteorologists compare those estimates with rain gauges to get a more accurate reading, but “it tends to be fairly reliable,” Taylor said. Estimates also showed that upstream, along Ellison Creek, another half-inch to an inch and a half fell, “so we have these couple of areas of heavy rain feeding in,” Taylor said.

Just downstream, estimates showed that rainfall was moderate, Taylor said.

Threats assessed after wildfires

After a wildfire, federal agencies frequently assess wildfire areas and identify threats to life, safety and property and other factors. A Burned Area Emergency Response team is created and often begins its work as firefighters are finishing theirs.

A BAER team for the Goodwin Fire, which started last month near Prescott, warned of possible post-fire flooding, for example. A BAER team issued similar warnings for the Pinal Fire, which burned near Globe last month.

No such warnings have been issued since the Highline Fire, which was declared contained in late June.

“There is a BAER team that has been assembled,” Templin said. “But they have not completed their report yet.”

Flash floods also can occur in the high desert, where a lack of vegetation can allow rainfall to moved quickly and accumulate in slot canyons.

One of the deadliest flash floods in Arizona history took place in 1997 at Lower Antelope Canyon, a narrow slot canyon near Page. A 40-foot wall of water swept through the canyon, which is only three feet wide in places, killing 11 hikers.

Flash floods are not always that devastating, but they can still be deadly. Youberg recalled a another flood that swept through the desert after the Oracle Hill Fire: “The flow was large enough that it got inside a man’s house and killed him.”

Wildfire can mimic the conditions that lead to flash floods in canyon country — a lack of vegetation, fast-moving water, narrow, rocky places where the water rises.

As investigators continued their work at the flood site Monday, officials paused to remember the flood’s victims.

“We send our deepest condolences to the families and friends who lost loved ones on Saturday,” Templin said.

How can I know if I’m at risk of a flash flood?

Hornung recommends getting a topographical map of whatever area you plan on exploring and identifying the interconnecting creeks and rivers. He also suggested checking with the National Weather Service before departing, as well as the U.S. Forest Service.

The former will warn of potentially dangerous weather, while the latter can identify wildfire “scars” that can make flash floods even more deadly.

“This is Arizona in the monsoons,” Hornung said. “Anywhere in central Arizona during monsoons, you have the possibility of a flash flood if you’re on a creek bed. You have to pay attention.”

What should I do if I’m caught in a flash flood?

Get to higher ground. Hornung said there’s not much you can do other than that.

“This flash flood was like an isolated tsunami,” Hornung said. “You can’t outrun it. You can’t run ahead of it. You might as well try to run out of it — get up out of the creek bed. Sometimes you can do that; sometimes you can’t.”

If you manage to escape a flash flood, Hornung recommends staying put in a shaded spot until help can arrive. If you have something eye-catching like a bright-colored tarp, use it to attract the attention of rescue helicopters.

“The people that move are the people that we don’t find,” Hornung said.

The same rule applies if a flash flood strikes while you’re in a car. Don’t get out and try to swim to safety. Stay in the car until a rescue team can catch up.

Hornung said he could warn against visiting creek beds during monsoon season, but said he doubted anyone would listen to him.

Instead, he recommends having someone monitoring the area from higher ground — like a lifeguard — to warn others if a flash flood is on its way.

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