(a) As used in this chapter, the term "navigable stream" means a stream which is capable of transporting boats loaded with freight in the regular course of trade either for the whole or a part of the year. The mere rafting of timber or the transporting of wood in small boats shall not make a stream navigable.

(b) The rights of the owner of lands which are adjacent to navigable streams extend to the low-water mark in the bed of the stream.