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Event Alert: On 3/12/23, the West Side MTB Series trail event will be taking place from 9 a.m. - 3 p.m. Trails will remain open but expect crowds of up to 240 bike riders. 

About the Park:

The 1,240-acre forested Black Diamond Open Space (BDOS) is located two miles north of Black Diamond and six miles south of Maple Valley. This special park contains portions of a protected migratory corridor called the Wildlife Habitat Network. It also contains streams, peat bogs, and wetlands.  

King County Parks is actively restoring the health of the forest with periodic stewardship activities such as invasive weed removal, thinnings, and plantings. Prior to public ownership, portions of the forest in BDOS were clear-cut. King County Parks replanted the forest in 2014. During this lengthy transition, forests can sometimes look a little scruffy. Active forest stewardship increases resilience to droughts, pestilence, and wildfire and makes for better habitat and ecological diversity. BDOS is a Forest Stewardship Council® (license code FSC-C008225) certified working forest.

BDOS straddles two distinct watersheds: The Cedar River Watershed and the Green River Watershed. Rock Creek, a fish-bearing stream runs through the site, which drains to Cedar River and out to Puget Sound. Ravensdale Creek also flows through the site, eventually draining to the Green River which eventually joins Duwamish River and into Elliott Bay. These waters are valuable for cutthroat trout, coho, sockeye, and chinook salmon. The presence of beavers and freshwater mussels are indicators of good water quality.

The largest and most publicly used portion of BDOS includes seventeen miles of trails built over many years for non-motorized uses.


Black Diamond Trail Coalition

Evergreen Mountain Bike Alliance - Black Diamond Open Space

Northwest Natural Resource Group


Park Activities: dog walking, hiking, horseback riding, mountain biking, nature observation, parking lot, potties, volunteer


Location: Two miles north of Black Diamond, or six miles south of Maple Valley on SR-169/Maple Valley-Black Diamond Rd/3rd Ave.

Nearby Bus Stops: 143 and DART Route 907 on SR-169 and SE 280 St or Black Diamond-Ravensdale Rd SE.

Parking: There are two gravel parking lots off SR-169/Maple Valley-Black Diamond Rd SE/3rd Ave. The southern, main parking lot is on the east side of SR-169 and can accommodate cars, trucks, and horse trailers. The northern, smaller parking lot is on the west side of SR-169. 


Trailheads: Trailheads are located in the parking lots.



Black Diamond Open Space Map


Park History:

The area was heavily mined for coal before it was harvested for timber on three occasions. A summary of this history is available in the January 2018 Draft Forest Stewardship Plan for Black Diamond Open Space, Ravensdale Retreat Natural Area and Henry's Ridge Open Space.


Relevant Links:

Black Diamond Open Space updates: Click to subscribe to an email newsletter for updates about the park.

November 2017 Community Engagement Summary

June 2005 Black Diamond Area Open Space Protection Agreement area map 

Black Diamond Area 2019 Stewardship Plan