The Authority may fix the lines along the bay and harbor of Charleston and the rivers and creeks flowing therein within which riparian owners may erect wharves, docks and other proper erections and fixtures for commercial, manufacturing or any other purposes. The Authority may cause the removal of any wharf, dock, wreck or other structure that may obstruct navigation or that may, in its opinion, be injurious to said bay, harbor, rivers or creeks, at the expense of the owner or the person causing the obstructions. But the rights of any owner of a wharf whose lines have heretofore been fixed by grant or by authority of State legislation are in no wise to be disturbed.