Wash. Admin. Code § 458-12-175
Leasehold interests in public lands other than those specified in WAC 458-12-155, are taxable as personal property to the holder thereof. (RCW 84.04.080; WAC 458-12-325) The fact that the land itself may be exempt from taxation is immaterial.
Improvements on public lands are generally considered personal property taxable to the owner thereof. (RCW 84.04.080) Whenever the improvement is a permanent fixture which cannot be removed without destroying it, such improvement shall be presumed to have become a part of the realty and would not be taxable, since owned by the exempt public body. (Pier 67, Inc. v. King County, 71 Wn.Dec.2d 89 (1967)) This presumption shall not be conclusive and can be overcome by clear evidence which indicates that the parties did not intend that the improvements become part of the realty.
Wash. Admin. Code § 458-12-175
Order PT 68-6, § 458-12-175, filed 4/29/68.