The Tonto Basin, also known as Pleasant Valley, covers the main drainage of Tonto Creek and its tributaries in central Arizona, at the southwest of the Mogollon Rim, the higher elevation transition zone across central and eastern Arizona. Although the word tonto means silly or foolish in Spanish, this place name is derived from the Apache word, Koun’nde, which means wild, rough people and refers to the indigenous Dilzhe’e Tonto Apache. Tonto Basin is mostly north-south trending and outflows into the Salt River at the extensive canyon reservoir called Theodore Roosevelt Lake.