Section 923.31 - Inland boundary(a) The inland boundary of a State's coastal zone must include:(1) Those areas the management of which is necessary to control uses which have direct and significant impacts on coastal waters, or are likely to be affected by or vulnerable to sea level rise, pursuant to section 923.11 of these regulations.(2) Those special management areas identified pursuant to § 923.21 ;(3) Waters under saline influence-waters containing a significant quantity of seawater, as defined by and uniformly applied by the State;(4) Salt marshes and wetlands-Areas subject to regular inundation of tidal salt (or Great Lakes) waters which contain marsh flora typical of the region;(5) Beaches-The area affected by wave action directly from the sea. Examples are sandy beaches and rocky areas usually to the vegetation line;(6) Transitional and intertidal areas-Areas subject to coastal storm surge, and areas containing vegetation that is salt tolerant and survives because of conditions associated with proximity to coastal waters. Transitional and intertidal areas also include dunes and rocky shores to the point of upland vegetation;(7) Islands-Bodies of land surrounded by water on all sides. Islands must be included in their entirety, except when uses of interior portions of islands do not cause direct and significant impacts.(8) The inland boundary must be presented in a manner that is clear and exact enough to permit determination of whether property or an activity is located within the management area. States must be able to advise interested parties whether they are subject to the terms of the management program within, at a maximum, 30 days of receipt of an inquiry. An inland coastal zone boundary defined in terms of political jurisdiction (e.g., county, township or municipal lines) cultural features (e.g., highways, railroads), planning areas (e.g., regional agency jurisdictions, census enumeration districts), or a uniform setback line is acceptable so long as it includes the areas indentified.(b) The inland boundary of a State's coastal zone may include:(1) Watersheds-A state may determine some uses within entire watersheds which have direct and significant impact on coastal waters or are likely to be affected by or vulnerable to sea level rise. In such cases it may be appropriate to define the coastal zone as including these watersheds.(2) Areas of tidal influence that extend further inland than waters under saline influence; particularly in estuaries, deltas and rivers where uses inland could have direct and significant impacts on coastal waters or areas that are likely to be affected by or vulnerable to sea level rise.(3) Indian lands not held in trust by the Federal Government.(c) In many urban areas or where the shoreline has been modified extensively, natural system relationships between land and water may be extremely difficult, if not, impossible, to define in terms of direct and significant impacts. Two activities that States should consider as causing direct and significant impacts on coastal waters in urban areas are sewage discharges and urban runoff. In addition, States should consider dependency of uses on water access and visual relationships as factors appropriate for the determination of the inland boundary in highly urbanized areas.