Technical Abstract: In 1990, the USDA-ARS Hydraulic Engineering Research Unit (HERU) was recognized as a National Historic Landmark by ASABE for its groundbreaking work and development of vegetated waterways design procedures. In 2000, ASABE acknowledged the vegetated waterway design criteria as an Outstanding Achievement of Agricultural Engineering in the 20th Century. Current design procedures have evolved, but their roots are in the early conservation programs of the 1930s when former ASABE Fellow and pioneer of vegetated design criteria, William O. Ree, began research on the subject in South Carolina while working for the Soil Conservation Service (now NRCS). He completed this work at HERU near Stillwater, OK in the 1940s. During this time, permissible velocities for vegetated channels and n-VR curves were developed as valuable design tools. The design criteria developed by Ree have been used worldwide for more than 60 years. In 1987, the design method evolved to a stress-based procedure. Today, NRCS is updating current design procedures in their Engineering Field Handbook and developing computer aided design software for vegetated waterways with the assistance of the USDA-ARS HERU. Researchers at HERU have continued to study vegetation in high stress flow environments that have played an important part in the development of the computational models SITES and WINDAM for evaluating vegetated auxiliary spillways and earthen embankments. SITES is used by NRCS and engineers worldwide for the design and analysis of watershed flood control dams. The evolution of the design procedures for grass-lined channels has had a tremendous impact on agricultural engineering.