Riverdale Bluffs Open Space | Adams County Construction Begins

136th Avenue & Riverdale Road

Adams County broke ground on Riverdale Bluffs Open Space on Monday, Aug. 17, moving the 225-acre property from master plan to active construction. The groundbreaking ceremony brought together the Adams County Board of Commissioners, Parks, Open Space & Cultural Arts staff, E-470 Authority representatives, and other project partners who have shaped the site’s development since planning began.

The property sits half a mile west of the South Platte River, overlooking the river valley and the downtown Denver skyline from a series of steep bluffs and rolling prairie terrain. It borders the county’s Riverdale Regional Park and the 81-acre Riverdale Dunes Golf Course open space, and sits less than a mile from Willow Bay Open Space and the South Platte River Greenway. The site was purchased using Open Space Sales Tax Grant Funds, which required a conservation easement held by Commerce City that permits passive recreation, including hiking, cycling, and wildlife viewing, while restricting active or motorized use.

Construction plans call for ADA-accessible concrete trails, singletrack biking routes, a trailhead with parking and restrooms, scenic overlooks, picnic shelters, and public art. A network of stair-climber trails will lead to the top of the main bluff, and mountain bike-optimized downhill tracks and skills loops are planned for more experienced riders. The hilly, high-relief terrain sets Riverdale Bluffs apart from the flatter open space amenities more typical of the Denver metro area.

“Riverdale Bluffs is an investment in both recreation and conservation, and we’re excited to see years of planning and community input move into construction,” said Adams County Board of Commissioners Chair Julie Duran Mullica. “This project will create new opportunities for residents to get outside, connect with our trail system, and enjoy this unique part of Adams County for generations to come.”

The project’s regional significance centers on a new partnership between Adams County and the E-470 Authority. The E-470 Regional Trail, long planned to parallel the E-470 highway along the north side of the property, will now be routed directly through Riverdale Bluffs, crossing the site from its northwest corner to the southeast near Riverdale Road and 136th Avenue before continuing east to a junction with the South Platte Greenway. The route requires a pedestrian overpass across Riverdale Road, one of two major roadway crossings the project will construct. The other is an underpass connecting the trailhead to 136th Avenue, Riverdale Ridge High School, and Rodger Quist Middle School to the west.

Habitat restoration is built into the construction scope as well. The site has been degraded over decades by oil and gas extraction, uncontrolled off-road recreation, and a private residence that has since been demolished, leaving much of its native shortgrass prairie overtaken by cheatgrass and other noxious weeds. Disturbed areas from construction will be reseeded with native prairie species, and the county has flagged the site’s higher-quality shortgrass prairie communities — concentrated on the main bluff’s steep slopes and a gully in the northwest corner — for longer-term protection.

The master plan that guided this month’s groundbreaking came out of a multi-year public process, including two public meetings, an online opinion survey, and stakeholder coordination with the E-470 Authority, the City of Thornton, and Bike Brighton. During the development process, the county also acquired the adjacent 15.5-acre Baumgartner property, a former residence at the top of a bluff that is expected to eventually house a nature center; preliminary access and parking planning for that site was folded into the current construction package, though its full build-out will come later.

Riverdale Bluffs adds a new type of recreational asset to Adams County’s open space system — one built around elevation, regional trail connectivity, and habitat protection rather than the flatter, more passive open space typical of the area. With construction now underway, the project positions the South Platte River Greenway, Willow Bay, and the growing neighborhoods west of Riverdale Road to be linked by trail for the first time.