Gross Reservoir is a stunning mountain lake tucked into the foothills west of Boulder in Boulder County, Colorado. Surrounded by tall canyon walls and pine-covered ridges, this Denver Water reservoir has become a favorite escape for Front Range residents who want a wilderness paddling experience without a long drive. The reservoir sits roughly 30 to 40 minutes west of Boulder and about an hour from the Denver metro area, making it one of the most accessible alpine-feeling lakes along the northern Front Range. What draws visitors back year after year is the combination of calm, motorboat-free water, dramatic canyon scenery, and a genuine sense of solitude midweek.
Paddleboarding and kayaking are the headline activities at Gross Reservoir. Because motorized boats are not allowed, the surface stays glass-smooth on calm days, and paddleboarders regularly cruise up toward the north inlet where the canyon walls grow taller and the crowds thin out. Kayaking and canoeing are equally popular, and the reservoir offers enough open water to make a full afternoon of exploring shoreline coves and inlets. A shuttle service now transports paddleboards, kayaks, and gear from the parking area down to the water, which is a significant convenience given the steep trail between the lot and the shoreline.
Fishing at Gross Reservoir draws anglers willing to hike for a quieter experience. Reviews note that catching fish here can be hit or miss, but the peaceful setting makes the effort worthwhile. Shore fishing requires packing light because the walk from the parking area to productive fishing spots is substantial, especially during the ongoing dam expansion construction. A valid Colorado fishing license is required.
Hiking options include a waterfall trail near the trailhead that reviewers describe as easy and scenic, suitable for families and older visitors. Restrooms are available at the trailhead. The trail to the waterfall can run dry depending on recent rainfall, but the route remains a pleasant walk regardless. Picnic areas with tables offer spots to sit and enjoy panoramic views of the reservoir and surrounding mountains.
Dispersed camping on the reservoir's north side is a major draw. Sites require a high-clearance four-wheel-drive vehicle to access, and popular spots like sites 24 and 29 offer secluded, wooded settings right along the water. Arriving early or visiting midweek is essential because campsites fill quickly on weekends. Walk-in and bike-in sites are also available for those without a truck.
Visitors should be aware of the ongoing Gross Reservoir Expansion Project, which began in 2022 and is expected to continue through approximately 2027. Construction has closed the south side access, rerouted parking, and created noise around the dam area. The gravel roads on the construction side are in rough shape from heavy truck traffic, though a paved route from Boulder offers a smoother alternative. The reservoir remains open on the north side with shuttle service operating on most days, but closures happen sporadically, so checking the Denver Water website before visiting is strongly recommended. Dogs are welcome but must stay out of the water. Swimming is not allowed at Gross Reservoir.