This study investigates headwall influence on local scour downstream of culvert outlets. Scour holes produced by discharging jets of varying duration and magnitude through circular culverts onto a horizontal sand bed were observed and mapped. The bed material was a uniform sand with a mean grain diameter d50 = 1.86 mm and a standard deviation σ = 1.33. The culvert diameter was 102 mm (4 in.). A series of expressions are developed describing the depth, width, length, and volume of scour hole as a function of time, discharge intensity, and headwall conditions. Results are presented in equation and graphical form. A criterion is presented for the design depth of a headwall at culvert outlets.