Wash. Rev. Code § 36.04.090
Douglas county shall consist of the territory bounded as follows, to wit: Beginning at the point where the Columbia Guide Meridian intersects the Columbia river on the northern boundary of Lincoln county; thence running south on said Columbia Guide Meridian to the township line between townships sixteen and seventeen north; thence running west on said township line to the range line between ranges twenty-seven and twenty-eight east; thence south on said range line to the section line between sections twenty-four and twenty-five in township fourteen north, range twenty-seven east; thence west on said section line to the midchannel of the Columbia river; thence up said channel of said river to the place of beginning, excepting therefrom the territory hereinafter constituted as Grant county.
RCW 36.04.090