RCW 36.05.010: Suit in equity authorized—Grounds.

Whenever the boundary line between two or more adjoining counties in this state are in dispute, or have been lost by time, accident or any other cause, or have become obscure or uncertain, one or more of the counties, in its corporate name, may bring and maintain suit against such other adjoining county or counties, in equity, in the superior court, to establish the location of the boundary line or lines.