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Open Space Charter Amendment

a photo of wetland surrounded by trees and bushes

In September 2022, King County Council approved a second update to the High Conservation Value Property Inventory, which provides a higher level of protection for some open space lands acquired by the County. With this update, King County added approximately 2,400 acres of open space to the list of properties protected under the Open Space Charter Amendment. King County updates this inventory approximately every five years; the first update was approved in 2015.

To view a map showing properties included in King County's High Conservation Value Property Inventory, click here.

For more information, please see these frequently asked questions.


In November 2009, King County voters approved the Open Space Protection Amendment to the King County Charter by more than 80%, which ensured that certain King County-owned properties listed on a “High Conservation Value Property Inventory” would receive a higher level of protection against changes of use or surplus.

Properties on the inventory were acquired “to conserve, preserve, protect, or enhance natural or scenic resources”, such as timberlands, streams, wetlands, wildlife habitat, or scenic vistas, and for “passive recreational opportunities,” such as areas for hiking, biking, and/or equestrian uses.

The King County Council can add or remove properties from the adopted inventory only by a supermajority of seven affirmative votes out of the nine council members. King County Council originally approved the ballot measure and inventory as Ordinances 16600 and 16601, which amended King County Charter Section 897 and Title 26 of the King County Code once implemented.

2015 Update

In 2015, the King County Council adopted the first update to the High Conservation Value Property Inventory as Ordinance 18177, adding 3,090 acres in fee and 845 acres in easement to the list of protected lands and making technical corrections to the inventory.

The updated High Conservation Value Property Inventory, per the 2015 update, includes 105 sites, with a total acreage of 16,503 acres in fee and 142,623 acres in easement. Parks is responsible for managing 104 of the sites (some have Transfer of Development Rights (TDR) property interests) and one is solely in the Transfer of Development Rights inventory (Girl Scout Camp).