Zone boundaries are intended to follow street, lot or property lines or other natural lines, such as the center line of watercourses, ditches or lagoons, unless such district or zone boundaries are fixed by dimension on the Zoning Map or by description, and shall include contiguous riparian lands subsequently acquired and/or filled and lands acquired by accretion or stream diversion by natural causes.

Where a zone boundary fixed by dimensions approximately follows and is not more than 20 feet distant from a lot line, such lot line shall be construed to be the zone boundary.