There was a discussion on this issue but I cannot find what forum or where it is located.
I believe it had to do with a par 3 course in Kent (Riverbend ??).
Generally the issue was as you stated it was city owned with signage prohibiting firearms and when it was addressed it was legal to carry as state preemption applies.
2019 W Meeker St
Kent, WA 98032-4216
United States
Toll Free: (877) 224-3250
F: (253) 856-6190
http://www.riverbendgolfcomplex.com
9.02.350 Possession of firearms or dangerous weapons at Kent Commons – Unlawful.
A. Subject to the exceptions set forth in subsections (B) and (C) of this section, it shall be unlawful for any person to possess a firearm; a dagger, sword, or knife with a blade in excess of three (3) inches; or any other weapon apparently capable of producing bodily harm, inside of the premises known as the Kent Commons located at 525 North Fourth Avenue in the city of Kent.
B. The prohibition to possession of a firearm shall not apply to a person licensed to carry a concealed weapon pursuant to RCW 9.41.070 or a person exempted from the licensing requirement by RCW 9.41.060.
C. This section shall not apply during shows, demonstrations, or lectures involving the exhibition of firearms or other weapons.
D. For the purposes of this section, firearm means a weapon or device from which a projectile or projectiles may be fired by an explosive such as gunpowder.
E. This section shall only apply to those areas of the Kent Commons that are within the Kent Commons building or that are contained to an area adjacent to the building by a temporary barrier during use for an event hosted by the Kent Commons.
F. A person who violates this section shall be guilty of a misdemeanor.
(Ord. No. 3621, § 2, 10-1-02)