No person shall do or permit to be done any grading which may obstruct, impede, or interfere with the natural flow of stormwaters, whether such waters are unconfined upon the surface of the land or confined within land depressions, natural drainage ways, unimproved channels, watercourses, improved ditches, channels or conduits, in such manner as to cause flooding where it would not otherwise occur, aggravate any existing flooding condition or cause accelerated erosion except where said grading is in accordance with all applicable laws including, but not limited to, the provisions of the grading ordinance. (Prior code § 9.31.1512)