Cowlitz county shall consist of the territory bounded as follows, to wit: Commencing at the Columbia river opposite the mouth of Lewis river; thence up Lewis river to the forks of said river; thence up the north fork of Lewis river to where said north fork of Lewis river intersects the range line between ranges four and five east; thence north to the line between townships ten and eleven north; thence west to the first section line east of the range line between ranges four and five west; thence south on said line to the Columbia river, and up the Columbia river to the place of beginning.