The Sawtooth Wilderness Area occupies 217,088 acres in the western portion of the Sawtooth National Recreation Area in central Idaho. The Wilderness Area consists primarily of the Sawtooth Mountains, a central headwaters source that includes headwaters of the North and Middle Forks of the Boise River, South Fork of the Payette River, and the Salmon River. Terrain is steep craggy peaks and deep valleys. Elevations range from 1,800 to 2,000 m (~6,000 ft) where the Payette South Fork and Boise Middle Forks exit the Wilderness on the west side, to 3,285 m (10,776 ft) at the summit of Thompson Peak. It includes approximately 40 peaks with elevations of 10,000 ft or higher.

This central Idaho wilderness area is remote from any major source regions. The nearest population centers are Boise and the Snake River Plain, 130 km (80 mi) straight line distance to the southwest and south with major intervening mountainous terrain. Locally, the site may be affected by pollutant accumulation in the basin, including smoke from wild and prescribed vegetative burning.

Haze forming pollution occurs most often in the summer months. Air quality data show increases in organic matter on the worst visibility days, most likely attributable to wildfire activity. In winter months, visibility impairment corresponds to increasing levels of nitrates and sulfates which may build due to wintertime inversion conditions.