The archived outline of the Trailhead Fire spans about 8.3 km from west to east and 5.2 km from south to north. CAL FIRE places the incident at along the Middle Fork of the American River near Todd Valley. The mapped boundary provides a second way to locate the event: it shows the extent around that reference location.
| Start listed by CAL FIRE | 28 June 2016 |
|---|---|
| County listing | El Dorado, Placer |
| Reported area in hectares | 2,284 ha (converted from acres) |
| Extent of the mapped outline | 8.3 × 5.2 km (west–east × south–north) |
| Containment entry in the archive | 18 July 2016 |
What the perimeter shows
The longer dimension runs east–west and is about 1.6 times the shorter one. A circular buffer drawn around the incident point would hide that difference. A road or settlement at the same distance from the point could fall inside or outside the mapped footprint depending on its direction.
Two estimates of area
The incident report gives 5,645 acres; the interagency feature stores 5,644.7 GIS acres. The mapped value is 0.3 acres below the reported value (0.01%). This compares two published measurements, not two observation times. The difference cannot be read as fire growth.
CAL FIRE also records structures threatened: 2,600. Those counts come from the incident record. A building inside the perimeter cannot be assigned a damage category from this map alone.
A similar-sized fire for comparison
The Willow Fire of 2015 is the closest match by reported acreage in this 100-case collection (5,702 acres). Its mapped spans are 4.7 by 9.4 km, west–east then south–north, versus 8.3 by 5.2 km here. The longer axes run in different directions. Matching on acreage would miss that contrast.
Sources and map method
- Trailhead Fire · CAL FIRE incident record
- NIFC interagency history · source perimeter (GeoJSON)
- Willow Fire · comparison incident
- Comparison perimeter · interagency record
Spans use the geographic extremes of a generalized boundary, converted to kilometres at its middle latitude. They are approximate map dimensions, not distances travelled by flames. The GIS acreage is the source attribute, not an area recalculated from the simplified outline.