Skip to main content
King County logo

Black Diamond Open Space (BDOS) is located in rural King County North of the city of Black Diamond and south of the city of Maple Valley, is a 1,240-acre multi-use King County Park. 

Black Diamond Open Space is managed as three geographic units:

North Unit
This area is the largest and most publicly used portion of BDOS. It is located north of the city of Black Diamond on both sides of SR 169 and includes Ravensdale Lake and  Creek. The lake, creek corridor, and a few large wetlands have a forested buffer; most of the site is young forest or shrubs. Trails appropriate for non-motorized use crisscross the property, with the main point of entry off of SR 169 (where there are two new parking lots). King County Parks' Green-to-Cedar River Regional Trail is planned for future development through this unit, west of SR 169.

Southwest Unit
This land is mostly steep forested slopes in the vicinity of Crisp Creek, off of 218th Ave SE, southwest of the city of Black Diamond.

Southeast Unit
This area is located near Icy Creek and the Green River in the vicinity of SR 169, southeast of the city of Black Diamond. The property supports stands of young and mature forest, located adjacent to hundreds of acres of public lands managed by Washington State Parks and Washington State Department of Fish and Wildlife. A small amount of additional acreage directly southeast of the city of Black Diamond is also a part of this unit.

The 1996 Black Diamond Urban Growth Area Agreement identified open space lands around the city for permanent preservation on the principle that for every one acre of urban land added to the urban growth area, four acres would be permanently preserved as open space ("4 to 1 agreement"). Two phases of annexations in 2005 and in 2009 dedicated most of the Black Diamond Open Space site currently in King County ownership; an additional phase or two of land dedications are anticipated between 2014 and 2021. Property purchases have also added acreage to the site over the years.

About the 2005 Black Diamond Open Space Protection Agreement
(between King County, Black Diamond, Plum Creek and Cascade Land Conservancy) 

Henry's Ridge, Black Diamond & Ravensdale Retreat Trails Map

Forest Stewardship in the Black Diamond area

King County Parks is developing a forest stewardship plan for Black Diamond Open Space, Ravensdale Retreat Natural Area and Henry's Ridge Open Space.

Draft Stewardship Plan

Community Engagement Summary


Sign up for BDOS e-news to keep up with the latest happenings!