Ordinary High Water Mark (OHWM) delineation has long been a part of identifying aquatic resources that may be subject to federal jurisdiction under Section 404 of the Clean Water Act and Sections 9 and 10 of the Rivers and Harbors Act of 1899. Despite the challenges found in OHWM delineation, because of the complexity and dynamic nature of inland waterways, a national manual providing guidance on OHWM identification and delineation has never been released. The National Technical Committee for OHWM, comprised of experts from Federal agencies and academia, developed and released the interim draft of the National OHWM Field Delineation Manual for Rivers and Streams. The manual provides a scientifically supported, weight-of-evidence framework to support efficient OHWM identification and delineation that are consistent, repeatable and defensible. Use of the National OHWM Manual will result in timely and more predictable identification and delineation of the OHWM across the Nation.