The Pole Creek Fire was discovered on Sept. 9, 2012, and ultimately grew to 26,795 acres. The fire investigation team concluded the probable cause of the fire to be the result of lightning from a small isolated thunderstorm in the area of Pole Creek Trailhead late in the day on Sept. 8, 2012. The team’s conclusion comes from numerous eye-witness interviews, lightning occurrence records, the exclusion of all other probable fire ignition possibilities.
To reach the conclusion the investigation team analyzed evidence of lightning strikes at the origin area. The investigation team was challenged by the complete consumption of fuels at the origin, which left no physical evidence. A large diameter fir tree that burned and broke off at the base was present in the specific origin. The interior of the tree was burned out. Additionally, numerous trees with lightning scars were present in the general origin area indicating the propensity of lightning to strike that area. Eye-witness interviews, photographs, and videos documented an isolated thunderstorm, which built over the Pole Creek Trailhead late in the day on Sept. 8, 2012 and further supported lightning as the cause of the fire. Several eye-witnesses independently reported lightning ground-strikes in the area.
The possibility of holdover lightning was considered by the team because lightning strikes were recorded late on August 5, 2012 within the vicinity of the Pole Creek Fire's origin. However, because of the significant time period between the last documented lightning storm and the ignition of the Pole Creek Fire, along with the extreme fuel models and conditions at the origin, the team determined it was unlikely the cause was holdover lightning.
The origin of the Pole Creek Fire is quite remote, a distance from roads and trails, and the dense fuels and ground cover in the area prior to the fire would make access to the area extremely difficult and time consuming, reducing the likelihood that the fire was intentionally set.
The intensity of the fire activity, safety considerations, and the large number of witness interviews contributed to the length of time the investigative team needed to conduct a thorough investigation.
The fire investigation team consisted of Washington and Oregon Forest Service Special Agents and Law Enforcement Officers, as well as an Oregon Department of Forestry/Oregon State Police fire investigator.