Wash. Rev. Code § 79.110.110
Any railroad company organized under the laws of the territory or state of Washington, or under any other state or territory of the United States, or under any act of the congress of the United States, and authorized to do business in the state and to construct and operate railroads, shall have the right to construct bridges across the navigable streams within this state over which the line or lines of its railway shall run for the purpose of being made a part of the railway line, or for the more convenient use thereof, if the bridges are constructed so as not to interfere with, impede, or obstruct navigation on the streams. However, payment for any right-of-way and any damages to those aquatic lands affected must be paid first.
RCW 79.110.110