The City of Boulder owns and manages the 700-acre Boulder Reservoir, which is also used for water storage and recreation. The Northern Colorado Water Conservancy District runs the reservoir as a water source. Recreation, drinking water, and irrigation are all done with it. Boating, swimming, tanning, water skiing, fishing, picnics, walking, running, cycling, and wildlife viewing are all common recreational pursuits at the reservoir.

The Boulder Reservoir has one of Colorado’s largest seasonally lifeguarded beaches.

With the exception of triathlons and lifeguarded open water swims, swimming is only permitted in this designated area with rafts at the Boulder Reservoir. Memorial Day weekend through Labor Day is considered swimming season.

Water temperature: In order to open the swim area, the water must be at least 60°F in the shallow region and 64°F throughout. The temperature varies from season to season. Call 303-441-3461 and press ‘0’ to speak with an attendant to get the current temperature.

Only swimming is allowed during the designated swim area hours. Except on Thursdays, when the pool area closes at 5:30 p.m. for weekly Stroke & Stride events, the swim area is typically open from 10 a.m. to 6 p.m.

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