When uncertainty exists as to the Conservancy District boundaries, the following rules shall apply:
   A.   District boundaries along a stream are intended to represent the high water line of a regional flood; provided, however, that along a stream, such line shall not be less than fifty feet (50') from the center of such stream.
   B.   District boundaries in a wetland area are intended to represent the edge of a swamp, marsh or other wetland area. The edge shall be defined as the mark delineating the highest water level which has been maintained for a sufficient period of time to leave evidence upon the landscape. The edge is commonly that point where the natural vegetation changes from predominantly aquatic to predominantly terrestrial.
   C.   District boundaries in a public park or common open space are intended to represent the property lines of such area. (1971 Code § 28-68)