Gross Reservoir

Gross shoreline
Gross Reservoir has 10.9 miles of shoreline.

Owned and Operated by Denver Water
Recreation Managers:
Denver Water: east side manager
Roosevelt National Forest/Boulder District: west side manager
Reservations:Day use area
Elevation: 7,282 feet (2,220 meters) – spillway
Capacity: 41,811 acre feet (one acre foot = 325,851 gallons)
Denver Water: 303-634-3641
U.S. Forest Service Boulder District: 303-541-2500
Boulder Sheriff: 303-441-3624
Colorado Parks and Wildlife: 303-291-7227


Named for Denver Water former Chief Engineer Dwight D. Gross, the reservoir was completed in 1954. It serves as a combination storage and regulating facility for water that flows under the Continental Divide through the Moffat Tunnel.

Standing 340 feet above the South Boulder Creek streambed, Gross Dam contains some 627,559 cubic yards of concrete. Gross Reservoir has a surface area of 440 acres and 10.9 miles of shoreline.


From Denver metro area:

  • Take Highway 93 north from Golden to Highway 72
  • Turn left (west) on Highway 72 toward Pinecliffe to County Road 77/Gross Dam Road
  • Gross Dam Road will take you to both the north and south access points

To reach the dam from Boulder:

  • Take Flagstaff Road west until it turns into eastern Gross Dam Road

Seasonal Information

  • Open year round.
  • Boating season starts on the Friday of Memorial Day weekend and ends Sept. 30.
  • Kokanee snagging runs from Sept. 1 – Jan. 31.
  • West site U.S. Forest Service closes from late fall to early spring: check with the U.S. Forest Service Boulder district for specific closure dates.

Operating Hours

Sunrise to sunset.

Recreation Opportunities

PDF document Map

Overview of available activities.


Cold water fishing; stocked by Colorado Parks and Wildlife. Also see the PDF document CPW’s fishery survey summary.

Current water elevation.

Ice Fishing
ice fishing
Ice fishing when conditions permit. Denver Water does not monitor ice conditions and those entering the ice should be aware of changing ice conditions and proceed at their own risk.

Boating is allowed (car-top non-motorized only) on the Friday of Memorial Day weekend through Sept. 30. No trailer-hitched boats are allowed.

Kayak access to the river below Gross Reservoir is available at the parking area below the dam.
The east side developed areas are for day use only. Sheltered tables also available.
Limited access. High clearance vehicles required. West side managed by Roosevelt National Forest. Area has seasonal closure; check with Boulder District.
Hiking is permitted from North Shore picnic area (trailhead to Rocky Point), South Side Dam, Miramonte picnic area, and Osprey Point (trailhead), to South Boulder Creek inlet.

Note: Water contact sports such as swimming, wading, scuba diving or other water activities are prohibited.

Other rules and regulations.