(a) A navigable tidewater is any tidewater, the sea or any inlet thereof, or any other bed of water where the tide regularly ebbs and flows which is in fact used for the purposes of navigation or is capable of transporting at mean low tide boats loaded with freight in the regular course of trade. The mere rafting of timber thereon or the passage of small boats thereover, whether for the transportation of persons or freight, shall not be deemed navigation within the meaning of this Code section and shall not make tidewaters navigable.

(b) For all purposes, including, among others, the exclusive right to the oysters and clams but not other fish therein or thereon, the boundaries and rights of the owners of land adjacent to or covered in whole or in part by navigable tidewaters shall extend to the low-water mark in the bed of the water.