Together with the Hulls Gulch ACEC, these five areas were designated to protect the Aase's onion (Allium aaseae) and its habitat. A. aaseae is a candidate species under the Endangered Species Act.
The Cartwright Canyon ACEC (400 acres) lies approximately 12 miles north of Boise and two-and-a-half miles east of Hwy-55.
The 40-acre Sand-capped Knob ACEC is located northwest of Hwy-55, 7 miles northwest of Boise. Another 40 acres nearby are designated the Woods Gulch ACEC, which is located to the north of the gulch itself, with Sand-capped Knob ACEC south of the gulch.
Sand Hollow (1,250 acres) and Willow Creek (1,060 acres) are closer to Emmett, three miles east and five miles southeast of the town, respectively.