The bill establishes new regulations for cities in Washington regarding the designation of historic landmarks. It mandates that cities must adopt or amend their ordinances, development regulations, and preservation ordinances to comply with specific requirements within one year. Notably, cities cannot designate a property as a historic landmark if it is less than 40 years old or if the designation would restrict the property's use, alteration, or demolition without the owner's written consent. Any designation made without this consent after the bill's effective date is considered void unless consent is obtained. However, exceptions exist for properties within historic districts or those over 125 years old, which can be designated without owner consent if proper documentation is provided.

Additionally, the bill reenacts and amends existing laws to clarify that certain actions taken by cities to implement these new requirements are not subject to administrative or judicial appeals. This includes actions consistent with the new sections added to chapters 35.21 and 35A.21 RCW. The bill aims to streamline the process for designating historic landmarks while ensuring property owners' rights are protected.