Wahkiakum county shall consist of the territory bounded as follows, to wit: Commencing at the southeast corner of Pacific county, on the Columbia river; thence up midchannel of said river to the southwest corner of Cowlitz county; thence north to the northwest corner of Cowlitz county; thence west on the northern boundary of township ten north to the line between ranges eight and nine west; thence south to the place of beginning.