In 2004, Estes Design Inc. and the University of North Carolina-Charlotte completed research on naturally formed plunge pools in urban stream systems. This research concluded existing methods for designing “stilling basins” and energy dissipating pools failed to predict naturally formed pool geometry seen in the field. It also concluded that naturally designed pools cost significantly less to construct than rip-rap aprons. Conventional Rip-rap aprons are designed to protect culvert outlets from scour for a calculated distance downstream where the hydraulic velocities decrease to a “non-erosive level”. However, in many urban settings a correctly designed apron may need a significant area and length, increasing cost, jurisdictional impacts and interrupting the natural fluvial sequence. Naturally designed plunge pools, in lieu of rip-rap aprons, reduce cost, maintenance and ecological impacts. Urban stream restoration as well as typical culvert maintenance work across the country are successfully incorporating these plunge pool design principles. In most cases, a natural plunge pool design can mitigate these ecological impacts by restoring regulated natural aquatic function including “passage” while also providing more efficient energy dissipation. This presentation will describe principles of scour and the research results leading to empirical design equations for successful culvert plunge pool design within natural stream dynamics. Several case studies will be presented showing successful design and construction.