To supplement both runoff and water-quality studies conducted on the Little River Watershed, a field-sized (0.34 ha), single-cropped study area, Station Z, was instrumented for the measurement of sub-surface and surface runoff. Station Z is located at the Coastal Plain Experiment Station in Tifton, Georgia. The soil on Station Z is a Cowarts sandy loam, which has a clay loam subsoil at depths of about 30 to 90 cm and a very low-permeability (0.01 cm/hr) parent material below 90 cm. Lateral subsurface flow moving above the parent material is intercepted at the lower bound by a drain tile on the down-slope and side-slope of the field. The drain tile directs the flow from each side to sharp-crested, v-notch flow-measurement devices. Surface runoff is directed by earthen-berms on each side of the plot to a flume for flow-measurement. Continuous records have been kept on Station Z since 1969.