Don Tennant is one of the founding fathers of modern instream flow policy and science.

　　In the early 1960s, Don began publishing his method and presenting it at regional and national workshops. Others familiar with his method initially called it the Montana Method. However by the late 60s, 70s and 80s, its popularity had increased and geographic scope of application spread throughout the world. The method was renamed the Tennant Method because of its expanded geographic application and to avoid confusion between the use of Don's method and other instream flow methods used in Montana and other locations where multiple methods were used.

　　When Don initially began publishing and presenting on the Tennant Method, instream flow values, issues, and protection were just starting to gain attention. The 1970s and 1980s were an era when the bulk of formal instream flow legal protection mechanisms were initially enacted.