The intense flames and smoke could be just the beginning of hazards caused by the Schneider Springs Fire.
A lightning strike in early August started the fire, which burned 107,322 acres 18 miles northwest of Naches.
A report released in October found that several areas near the fire could see debris flows if they experience heavy rain. The report was based on in-depth soil analysis and on-the-ground research by the Washington Geological Survey's Wildfire-Associated Landslide Emergency Response Team, or WALERT.
Team lead Trevor Contreras, a geologist for the Washington Department of Natural Resources, said landowners should be aware of those risks as well as the possibility of flash flooding like they've never seen before.
"We don't typically expect a lot of people to be killed by flash flooding," Contreras said. "To us as geologists, we see debris flows as the big bad wolf. They're the ones that bring down huge boulders and trees and there's not really a good way to get out of the way of that sort of thing."
The hotter they burn, the more fires increase the risk of debris flows by producing hydrophobic, or water-repellant, soil conditions. That can in turn cause roots to decay and lose their grip on large rocks while making areas more prone to erosion when heavy rain occurs.
Contreras said debris flows typically stay in a channel and sound like a freight train roaring down a slope. They have the potential to take down cabins and other structures. Although they're impossible to outrun, Contreras said some debris flows may give enough advance warning to provide time to seek higher ground or at least get behind a tree and hope it holds.
Danger zones
The report by Contreras and his team found multiple areas of increased risk just outside the burn area of the Schneider Springs Fire, which could cause more hazards than the Evans Canyon Fire. The Evans Canyon Fire burned between Naches and Ellensburg in 2020.
The Evans Canyon area didn't have as much vegetation. Contreras, who also wrote the WALERT report for that fire, said there were fewer cabins near the burned area. The Schneider Springs Fire saw higher soil burn severities and created more potential risks for cabins and recreation spots.
Overall, though, Contreras said compared to places like Okanogan County, fewer landowners in Yakima and Kittitas counties build at the base of alluvial fans. Those slopes formed by sediment deposits from historical flows can funnel high concentrations of debris and water to the valley floor.
Perhaps the best example Contreras found was near Rattlesnake Creek, especially the cabins on alluvial fans on the north side, where the report found a heavy storm would have a 61% to 72% chance of generating debris flows. The team didn't get a chance to reach out to many cabin owners, but Contreras said they should be alerted to the risks and be aware that the access road might be affected in a storm.
Cabins by Cliffdell and a little farther up State Route 410 off of Lost Creek Road could also see some issues, according to the report. Contreras said a culvert crossing Lost Creek near the campground and the Edgar Rock trail could be blown out by a flash flood made more powerful by the fire impacts.
"I expect the Forest Service will sign that area, if not close it," Contreras said. "When we worked with them, we helped come up with soil burn severity mapping that shows us what areas have been burned most severely."
The same holds for the Scab Creek trail. Contreras noted a dispersed campground near Bumping Lake might hold new dangers. If a heavy storm causes a debris fall, the impact could be strong enough to push the river into the campground.
Tips for caution
The biggest new risks from debris flows will last about two years, with heavy enough rainstorms most likely to occur in spring or summer.
Rapid enough snowmelt could cause similar effects, and Contreras said elevated risks exist for about five years. He recommends buying flood insurance for at least the first two years, possibly up to five, and paying close attention to weather reports.
Forest Service spokesperson Victoria Wilkins said the agency is working to put up signs and warn the public to be cautious when downslope of a burned area. Contreras suggested not camping near rivers or in drainage areas if thunderstorms are in the forecast.
He warned that sometimes even areas where the weather seems nice can be affected by thunderstorms at a higher elevation some distance away. Rapid snowmelt could cause similar problems but if that doesn't happen and it never rains heavily — defined as a quarter inch of rain in 15 minutes by the WALERT report — then the burned areas may not cause any hazards.
"If we get one thunderstorm this coming summer, all hell can break loose and you can get a lot of flooding and debris flows out of these things," Contreras said. "It's just tough because a hazard might not come to fruition, but it could. And it's good for people to start preparing now."
