States develop guidelines to protect and manage forest riparian resources. A review of 37 eastern states' forest riparian guidelines (e.g., BMPs, regulations) for timber harvesting revealed the primary focus is water quality protection adjacent to perennial and intermittent streams and lakes. A commonly recommended riparian management zone is 50-foot wide with 50–75 percent crown closure (or 50–75 ft2/acre of residual basal area), although the specific guidelines in each state vary tremendously. Additional values which increase the width of the riparian management zone are based on: (1) waterbody size, (2) slope of the ground adjacent to the waterbody, or (3) by incorporating slope effects with waterbody size or soil erodibility. While science cannot specify the management prescriptions needed to protect all riparian functions across all sites, understanding site-specific conditions can facilitate effective guideline implementation. There is a need for additional research within these areas to address a variety of questions.