Except as provided for by a permit, no person shall do, or permit to be done, any grading which may obstruct, impede or interfere with the natural flow of storm waters, in such manner as to cause flooding where it would not otherwise occur, aggravate any existing flooding condition or cause accelerated erosion. This section applies whether such waters are unconfined upon the surface of the land or confined within land depressions or natural drainage ways, unimproved channels or watercourses, or improved ditches, channels or conduits. In no event shall grading activities cause or contribute to the violation of provisions of any applicable NPDES storm water discharge permit; nor shall grading activities obstruct, impede or divert the free flow of surface water to those who hold rights to such surface water without first obtaining the written permission of the affected owner/s and the appropriate watermaster, where applicable.