Synthesizing the Scientific Foundation for Ordinary High Water Mark Delineation in Fluvial Systems
U.S. Army Engineer Research and Development Center (ERDC) Hanover United States
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For more than 100 years, the ordinary high water mark OHWM has been used to define water boundaries in a number of contexts in the United States. This Special Report summarizes the scientific literature pertaining to the indicators used to identify the OHWM in fluvial systems, building on more than a decade of research and publications related to the OHWM in the ongoing process to implement the Clean Water Act and the Rivers and Harbors Act of 1899. This report does not change or redefine the indicators used to identify the OHWM, nor is it a manual for how to delineate the OHWM. This report first reviews established concepts in river science that relate to the OHWM then reviews various sources of information that can be used to delineate the OHWM, discusses geographic variations in OHWM indicators among river segments, reviews human activities that can affect the OHWM, and finally presents examples of the OHWM in diverse channel types and regions.