Nothing herein provided shall be so construed as to prohibit the owners of lands within any area threatened by floodwaters or wetlands from lawfully filling, draining, constructing levees and bulkheads or otherwise improving their land with clean fill so as to eliminate or reduce the danger of flood or the erosion of soil so long as it is done in compliance with any federal, state, county or local regulations governing drainage rights-of-way. Topographical plans for such work shall be approved by the Township Engineer.