Winds kicked up big swirling clouds of gray and white ash that blew down from blackened and all but barren hillsides.
It settled below the peaks on a scorched landscape denuded of grasses, where greenery had been seared off shrubs and small trees across a broad stretch of desert.
"It makes you feel horrible. That’s just painful to look at," said Chris Frisbee as she surveyed the scene Friday at the western edge of the Tonto National Forest.
Frisbee, interim chief ranger for the forest’s Cave Creek District, joined other U.S. Forest Service officials assessing the damage done by the Cave Creek Complex fire that raced through more than 248,000 acres north of the Valley since igniting June 21.
The blaze was 95 percent contained by Friday and firefighters expect to have it fully under control by Tuesday. But in its aftermath it will leave some environmental scars that won’t heal for years, or even decades, Forest Service scientists said.
Wide swaths of charred Sonoran Desert terrain from just north of Scottsdale and Carefree west to the Agua Fria National Monument area about 15 miles north of Black Canyon City could cause an array of environmental problems, officials said.
Most serious among them is an increased risk of flash flooding that could further threaten wildlife habitat, public recreation areas and even roads and residential areas downstream of the Tonto Forest, said Todd Ellsworth, head of a team of engineers and ecologists evaluating the impact of the second largest wildfire to hit Arizona.
Satellite images used to map the fire area show that the blaze burned at medium to high intensity over at least 35 percent of land it covered, said Norm Ambos, a Forest Service soil scientist.
That is severe enough to cause much of the ground to become water-repellent, Ambos said.
The water-repellent condition provides a slick, nonporous surface ideal for strengthening the flow of floodwaters and contributing to extensive soil erosion, he said.
As waters from monsoon storms set to begin within a week or two move downstream, the soil and plant life loosened by the wildfire also could clog watersheds with sediment, threatening aquatic wildlife and interrupting flows into reservoirs that hold much of the Valley’s water supply.
Ambos said fire damage spread far enough that it will have an impact on all three watersheds that run through the area — the Verde River, Agua Fria River and New River watersheds.
Some of the early rehabilitation work likely will involve removing fallen trees and other woody materials from the Camp Creek area several miles north of Scottsdale to prevent clogging of the Verde River watershed, he said.
Even so, heavy sediment from the fire area can be expected to soon make its way down the Verde to Bartlett Reservoir.
Ecologists said they also are concerned that the fire will result in the further spread of non-native, invasive weeds in the Tonto forest.
The expanses of ground from which native Sonoran Desert grasses have been burned away "are great seed beds for the invasives," Frisbee said.
It’s the dense non-native plant life that provided much of the fuel for the wildfire and heightened its intensity, Forest Service officials said.
Several valuable archaeological sites have been lost to the fire, said Scott Wood, chief Tonto forest archaeologist.
The remnants of five centuries-old pit houses, once part of a Hohokam settlement, were scattered when a firebreak had to quickly be cut across the area, he said.
He’s also worried the fire could have charred some boulders bearing Hohokam rock art.
Although desert wildlife is resilient, the large wildfire worsens the loss of habitat for populations of deer, javelina, coyotes, foxes, rodents and birds that already have been displaced by drought and other wildfires near the Valley in recent years, said Forest Service spokesman David Elkowitz.
Much of the flora in the burned areas most likely won’t recover its scenic appeal for years. Thousands of trees and cactuses were burned badly enough that their survival is in doubt, said Carol Engle, a member of the rehabilitation team.
Forest Service officials said they plan to do some emergency rehab work — mostly to stabilize loose soil and prevent flash flooding — before monsoon rains arrive.
Long-term restoration work will take at least two to three years, Ambos said.
But the wildfire burned such a large area that extensive rehab efforts, such as reseeding the most heavily burned area, would demand far more resources and funds than the Forest Service has available, officials said.
On most of the damaged land, Ambos said, nature will have to heal itself.
Damage done by Cave
Creek Complex fire
• More than 248,000 acres burned
• Thousands of trees and cactuses, including many old saguaros, may not survive burn damage
• Vegetation was burned away in many prime desert wildlife habitat areas
• Remains of five pit houses in valuable Hohokam archaeology site lost when a firebreak had to be cut through the area
• Some soil burned badly enough that it will become water-resistant, increasing chances for flash flooding
• Soil erosion could lead to sediment clogging watersheds that feed into Valley reservoirs
• Areas where native desert grasses were burned away could be taken over by non-native invasive weeds that provide abundant wildfire fuel