Three years after the Castle Rock Fire roared through the mountains around Ketchum, the northern flanks of Bald Mountain are still covered in blackened, fire-killed trees.
The undergrowth, however, is almost impossibly green, providing evidence for the common theory that fire is good for the land.
"It was black for the first year," said Ketchum District Ranger Kurt Nelson. "Everyone was afraid it would look like a moonscape, but it came back."
On this date three years ago, the Castle Rock Fire had burned more than 42,000 acres and had reached the summit of Baldy, via the ski mountain's back side. The burn would reach 48,520 acres and threaten homes in the Warm Springs and Greenhorn Gulch areas before being contained on Sept. 4.
Nelson was on the scene in 2007, helping to encourage firefighters and assess damage. Before the fire was even officially declared out, Nelson said, he and Forest Service crews were assessing the damage and developing a burned-area emergency rehabilitation plan.
The main concern was soil erosion, as high-intensity burns create what is known as hydrophobic soil, which resists absorbing water.
As a result, rain water stays on the surface, dragging some soil with it as it runs off and creating debris flows, flash floods and mudslides.
One thunderstorm immediately after the fire's containment in 2007 created a debris flow that blocked Warm Springs Creek near Frenchman's Bend, raising the water level for a distance of 300 feet upstream of the dam.
Debris flows in June 2009 deposited thousands of cubic yards of rock and soil onto the road near the Upper and Lower Board Ranch, west of Ketchum. Nelson said the road had to be closed five or six times last summer due to the flows.
"The costs don't stop once the fire is out," Nelson said.
The ranger district received funding from the Forest Service to aerially spread mulch over 432 acres that were deemed to be at high risk for soil erosion.
Nelson said the mulch mainly protects from wind and from the impact of raindrops.
Nelson said each raindrop that hits hydrophobic soil displaces a little bit of soil, and the cumulative results can be dramatic. The mulch softens the blow of the raindrops and keeps soil in place. Some of the wood-strand mulch can still be seen in the Warm Springs area, and continues to help the soil retain moisture so the grasses and shrubs that used to be in the area can recover more quickly.
Though plant growth in burn areas is seen as a sign of recovery, fires also create seedbeds for noxious weeds. According to Nelson, the ranger district received $1.2 million in Forest Service funding to prevent noxious weeds from gaining a foothold in the burn areas.
Extensive damage was also done to the 86 miles of trails burned. The ranger district completed restoration of the Eve's Gulch trail last summer, and crews are now working on reconstructing segments of the Warfield, Red Warrior and Rook's Creek trails.
Warfield and Red Warrior are expected to open to motorized use next spring, and construction on Rook's Creek is slated for next summer.
A 10-person South Idaho Corrections Institution crew did some of the early drainage work on the trails. This group of prisoners worked with a Hotshot and Sawtooth National Forest crew to route water and sediment off trails and prevent further erosion.
"They loved it, to be outside," Nelson said.
As for the future of the burn area's recovery, Nelson said the fire's impact will be long-lasting.
"There will always be fire scars there," he said.
He said the blackened stumps on the north and east sides of Baldy will take five to 10 years to disappear.
The soil on the slope is starting to break down and accept water again, allowing vegetation to take root. Nelson said it may take 10 to 20 years for enough seedlings to take root and begin the re-establishment of the forest.
The brilliantly green undergrowth is thriving in part because of the fertilizer slurry the Forest Service uses during wildfires to smother flames and prevent spread. But the undergrowth is also due to more natural means.
"Fire itself is a natural fertilizer," Nelson said.
High levels of nitrogen found after a burn help the vegetation in the area regenerate, though Nelson said there may be other unknown ways fires help boost growth.
"[Fire] does result in an amazing vegetative response," he said.
One such response was the intense period of willow and aspen growth in Adams Gulch north of Ketchum. Willows and aspens burned to the ground in the area, but Nelson said he saw 4 to 5 feet of growth in the season after the fire.
"You'll see thousands of aspens taking off," Nelson said, mainly because the thick canopy from lodgepole pines no longer exists.
While Baldy's evergreens may not fill the back slopes for a few more decades, perhaps aspens and the other vegetation will create a different kind of recovery.
"Fire's just part of our natural cycles," Nelson said. "It's one of the natural agents of change."
Katherine Wutz: firstname.lastname@example.org