This report summarizes the geomorphology and hydrology of the three principal tributary streams of the Bill Williams River in western Arizona. The Bill Williams River basin drains most of west-central Arizona, straddling Mohave, Yavapai and La Paz counties (Figure 1). The principal tributaries of the Bill Williams are Big Sandy River, which heads east of Kingman, and Santa Maria River, which heads near Hillside. These tributaries join to form the Bill Williams River at what is now Alamo Lake. Burro Creek is the largest tributary of Big Sandy River, entering south of Wikieup.