A semiautomated method for objectively interpreting and extracting the land-water interface has been devised and used successfully to generate multiple shoreline data for the test States of Louisiana and Delaware. The method is based on the application of tasseled cap transformation coefficients derived by the EROS Data Center for Landsat 7 Enhanced Thematic Mapper Data, and is used in conjunction with ERDAS Imagine software. Shoreline data obtained using this method are cost effective compared with conventional mapping methods for State, regional, and national coastline applications. Attempts to attribute vector shoreline data with orthometric elevation values derived from tide observation stations, however, proved unsuccessful.