Hyporheic flow, the flow of water through the permeable material immediately surrounding a river, is important for nutrient cycling, dissolved oxygen transport, and contaminant transport. In addition, there is recent concern regarding the role of hyporheic flow on the contamination of rivers following oil spills. To better understand hyporheic flow paths and velocities, it is important to measure hyporheic flow at high spatial and temporal resolution. A practical method to measure hyporheic flow in a laboratory flume based on dye injection, digital images, and moment analysis was developed. An experiment conducted using a single gravel bar demonstrated good agreement between observations and estimates based on image processing. The measured hyporheic flow field showed upstream and downstream flow that discharged downstream of the bar top, the presence of a flow divide and flow stagnation, and hyporheic flow velocities indicative of turbulent flow for which Darcy’s law is not applicable.