Donnell Fire (2018): mapping the 36,450-acre footprint

The archived outline of the Donnell Fire spans about 23.3 km from west to east and 16.6 km from south to north. CAL FIRE places the incident at Near Hwy 108, Donnell Lake area in the Carson Iceburg Wilderness. The mapped boundary provides a second way to locate the event: it shows the extent around that reference location.

Start listed by CAL FIRE1 August 2018
County listingTuolumne
Reported area in hectares14,751 ha (converted from acres)
Extent of the mapped outline23.3 × 16.6 km (west–east × south–north)
Containment entry in the archive4 January 2019
Perimeter collection method as recordedInfrared Interpretation
Donnell Fire historical perimeter; north up. Approximate spans 23.3 by 16.6 kilometres.
Generalized historical perimeter. Source: NIFC interagency fire perimeter history.

What the perimeter shows

The two spans differ by only 6.7 km. That does not make this a circular burn: the dimensions measure the outermost coordinates, leaving indentations and gaps invisible. Use the polygon itself, rather than its enclosing rectangle, to check whether a location intersects the footprint.

Two estimates of area

The incident report gives 36,450 acres; the interagency feature stores 36,461.4 GIS acres. The mapped value is 11.4 acres above the reported value (0.03%). This compares two published measurements, not two observation times. The difference cannot be read as fire growth.

A similar-sized fire for comparison

The Pier Fire of 2017 is the closest match by reported acreage in this 100-case collection (36,556 acres). Its mapped spans are 16.1 by 15.6 km, west–east then south–north, versus 23.3 by 16.6 km here. The broad proportions are comparable. That does not establish that fuel, wind or suppression tactics were similar.

Sources and map method

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.