Boulder Reservoir is a 700-acre, multi-use recreation and water-storage facility, owned and managed by the City of Boulder and operated as a water supply by the Northern Colorado Water Conservancy District in the state of Colorado in the United States. It is used for recreation, drinking water and irrigation. Popular recreation activities at the reservoir include boating, swimming, sun bathing, water skiing, fishing, picnics, walking, running, cycling and wildlife viewing.
The city initially bought land for construction of the reservoir from the Axelson family's dairy farm and began construction on May 1, 1954. The reservoir construction was completed on February 11, 1955 and began filling with water from the Colorado-Big Thompson Project that April (via what is now the Boulder Feeder Canal). Two months after being filled, 75 tons of sand were delivered to create a beach along the reservoir's southeast shore. The reservoir's construction cost was $1,158,027.
Though the lake's initial purpose was the storage of irrigation and drinking water, the reservoir quickly became the region's most popular destination for boating, swimming and fishing. During the first 4th of July celebration held at the reservoir in 1955, more than 1,400 cars paid the 25 cent admission to picnic, swim and enjoy the festivities. That August, the first boating licenses were sold.
Eventually, a Quonset hut, outhouses and a concession stand were constructed. In the early 1980s, after passage of a city bond initiative, the beach was moved to its present location toward the more protected southwest "corner" of the reservoir and the facility received its first running water along with many of its current structures. The reservoir facility now includes 13 picnic sites, boat moorings and rentals, a snack food concession, a seasonally-guarded swim beach, restrooms, showers, volleyball courts, horseshoe pits, and ramp access for motorized and non-motorized watercraft. Runners, cyclists and hikers can also enjoy a mostly un-paved, 5 mile route around the reservoir.
The reservoir currently supplies approximately 20 percent of Boulder's drinking water. Between 80 and 90 percent of that water comes from the Boulder Feeder Canal with the remaining 10 to 20 percent coming from seasonal creeks and ditches. The reservoir is typically filled by June and drawn down to half of its 13,270 acre-feet capacity by September.
The reservoir and its surrounding environs provide habitat for a variety of fish and wildlife including bass, catfish, walleye, osprey, raptors, herons, owls, rabbits, snakes and prairie dogs.