Report and burn severity maps show impact of Cedar Creek Fire
24 November 2022
Published by: https://www.statesmanjournal.com
USA – The Cedar Creek Fire didn’t burn as hot or destructively as the recent Labor Day fires and the majority of recreation sites escaped intact or with minor damage, according to a post-fire analysis of the 127,311-acre megafire that burned around Waldo Lake this summer outside Oakridge.
The report found that while there would likely be erosion and landslides during winter in burned areas, it’s unlikely to bring water quality concerns for nearby municipal and domestic drinking water.
The report comes from a U.S. Forest Service’s Burned Area Emergency Response team that came in post-fire to measure elements such as soil burn severity and vegetation loss while projecting the impact on water, wildlife, forest health, recreation and other factors.
“The fire burned a mosaic pattern through most of the area, and the majority burned with low and moderate severity, although areas of high severity are present north and northwest of Waldo Lake and on high elevation ridges and spurs in the southern and western portions of the burned area,” the report said.
Although the fire exploded during an east wind event in early September — and made a large enough run to bring level 3 evacuations to Oakridge and the surrounding area — the fire didn’t take any lives or burn any homes.
The fire was expensive and often made air quality miserable. Fire suppression and repair costs reached at least $132 million while the blaze brought 37 days of poor air quality to Oakridge and eight in Eugene.
Fire burned at lower severity than Labor Day fires
The Cedar Creek Fire burned forest at a lower severity than the Labor Day fires.
On Cedar Creek, 36% of the fire burned at a high or moderate soil burn severity.
In high burn severity almost all the trees and vegetation has been consumed and the soil has also been cooked, making it more difficult to regrow vegetation. In moderate severity, many of the trees are killed but there can be some vegetation left and the soil can regrow more easily. Low-burn severity is often viewed as “good fire” because it removes built-up fuels and can spur regrowth while leaving most trees alive.
In the Labor Day fires, 71% of the Holiday Farm Fire burned at high or moderate severity, while on the Beachie Creek Fire it was 62%, the Riverside Fire was 52% and the Lionshead Fire was 47%.
More:New maps show where Oregon wildfires hit hardest, detail Opal Creek, Mt. Jefferson, McKenzie, Umpqua
Forest Service and fire officials that put the report together were not available to speak to their study and flesh out details by press time.
Origins of the fire
The Cedar Creek Fire began on Aug. 1 when a spate of lightning strikes ignited a number of fires across the Cascade Range. It originally ignited 15 miles east of Oakridge and 5 miles west of Waldo Lake on the Willamette National Forest.
Fire crews attempted to put the fire out originally, before turning to a containment strategy due to what they called “unsafe conditions” for firefighters to go direct on the blaze deep in the Waldo Lake Wilderness.
“The fire grew rapidly in the first few days in inaccessible terrain, then was held at control features for around one month,” the report says.
Indeed, recreation at Waldo Lake stayed open for much of the summer even as the fire burned just across the lake. At that point, fire officials said the fire was burning at a nice low intensity that was beneficial for forest health, in a way that clears up brush and ground fuels without killing many trees, then-fire spokeswoman Kassidy Kern said.
However, in early September, a hot and dry east wind event arrived and caused the fire to explode, running to within a few miles of Oakridge and bringing widespread evacuations.
Extended dry conditions that lasted well into October allowed the fire to smolder for weeks. Fire crews also did extensive back-burning — intentionally lighting fires around the blaze — to help bring it under control. Heavy season-ending rain brought the fire to full containment.
Areas where the fire burned hottest
The most concentrated areas of high soil burn severity was in the Skookum Creek, Upper Salmon Creek and Black Creek subwatersheds, the report said.
The fire also reburned and torched the forest on the north side of Waldo Lake in the scar of the 1996 Charlton Fire.
“Wind alignment restricted high intensity fire mostly to the ridgetops in the area west of Waldo Lake,” the report said.
The burn is expected to bring an initial flush of ash and burned materials, erosion in drainages and on steep slopes in the burned area and increased peak flows and sediment transport and debris flows, the report said.
However, “these responses are unlikely to lead to increased water quality concerns for municipal and domestic drinking water providers within and downstream of the fire, due to the mosaic nature of the burn and the high percentage of unburned or low severity fire in most watersheds.”
There will also be an elevated risk of rockfall, which could bring dangers to roads where they cross steep and burned hillslopes particularly in the Black Creek and Salt Creek drainages, the report said.
Recreation
The Cedar Creek Fire burned near numerous campgrounds, boat launches, trailheads, 142 trail miles and the high-use Waldo Lake basin, the report said.
“Hazard trees are present around many of these sites and facilities; these will require mitigation (felling) to protect the structures and users,” the report said. “In addition to hazard tree felling, hazard and closure signage and preventative erosion control on 18 miles of trail are recommended.”
Most surveyed recreation facilities survived intact or with minor damage, the report said.
However, the status of popular Blair Lake campground’s facilities is not yet known, the report said.
The Waldo Lake Lookout did remain intact after fire crews wrapped it in foil designed to repel wildfire.
More notes from the report:
Botany
Native plant communities that were burned at moderate to high severity are threatened by the introduction and spread of noxious weeds, the report said.
Areas of special botanical concern include stands of whitebark pine on Fuji Mountain and in the Waldo Lake Wilderness, as well as rare and sensitive plant populations and associated special habitats distributed across the different vegetation types within the burned area.
Wildlife
The Cedar Creek Fire is within the current range of the northern spotted owl, a species that is listed as threatened under the Endangered Species Act. In critical spotted owl habitat 2.664 acres burned with high severity and 9,045 acres burned with moderate severity.
“Threats include additional loss of habitat in the fire area due to blowdown, mass soil movement, flooding, and insects and disease. Each of these threats could result in additional mortality to remaining live trees and further reduce NSO suitable habitat and usable critical habitat and threaten the viability of nesting territories,” the report said.
Fisheries
The fire could have a negative impact on federally-listed salmon, steelhead and bull trout in the North Fork Middle Fork Willamette River and Salt Creek, the report said, by increasing peak river flows laden with debris and increase sediment leading to mortality of eggs and fry.
However, more wood in the river from downed trees could help improve habitat quality.
To read the full report, go to tinyurl.com/mvp6f4ah
