In the United States, bridge scour technology is discussed primarily in three Federal Highway Administration (FHWA) publications: "Hydraulic Engineering Circular (HEC) 18: Evaluating Scour at Bridges"; "HEC-20: Stream Stability at Highway Structures"; and "HEC-23: Bridge Scour and Stream Instability Countermeasures." Together, these documents provide guidance to state highway agencies that is necessary for completing comprehensive scour and stream instability evaluations for the design of new bridges and for repairing existing bridges. Experience has shown that the relationships among the three documents are not always readily apparent, and some scour evaluations have relied primarily on HEC-18. A comprehensive flowchart that illustrates the interrelationship among the three FHWA scour-related documents has been developed. In addition, in 1998, FHWA, the Transportation Research Board (TRB), and the American Association of State Highway and Transportation Officials (AASHTO) sponsored a scanning review of European practice for bridge scour and stream instability countermeasures. In 1999, the American Society of Civil Engineers (ASCE) published a compendium of papers on stream stability and scour at highway bridges, and FHWA prepared an annotated bibliography to support revisions to the three HECs. It is anticipated that the flowchart and the substantial information from the scanning review, the compendium, and the annotated bibliography will be included in the next revisions to HEC-18, HEC-20, and HEC-23. On the basis of information from these sources, a comprehensive approach to bridge scour and stream instability evaluations is outlined, and an overview of planned revisions to the three FHWA HECs is provided.