
Union Reservoir in Longmont invites paddlers, swimmers, and anglers to enjoy a versatile water experience with sandy beaches, mature shade, and dog-friendly spots. Learn why this reservoir stands out as a family-friendly outdoor hub just outside Denver.
Union Reservoir in Longmont invites paddlers, swimmers, and anglers to enjoy a versatile water experience with sandy beaches, mature shade, and dog-friendly spots. Learn why this reservoir stands out as a family-friendly outdoor hub just outside Denver.
Union Reservoir in Longmont, Colorado, offers a refreshing outdoor getaway centered around water sports, picnicking, and family-friendly fun. Located just outside the city, this reservoir provides a broad, calm surface ideal for paddleboarding, fishing, and swimming. Unlike smaller urban ponds, Union Reservoir’s sandy beach and clearly defined swim areas make it particularly welcoming for beginners and families with kids. The water remains shallow near the edges, allowing easy entry and exit, while mature shade trees around the shoreline offer moments of relief from the summer sun.
What sets Union Reservoir apart is its balance between calm recreational waters and the open space that permits wind-driven paddleboarding challenges. Visitors frequently highlight the well-maintained facilities, including designated dog-friendly areas, making it a practical destination for pet owners seeking active outdoor time. While the reservoir doesn’t sit at the foot of Colorado’s towering peaks, the distant mountain views add a scenic backdrop without dominating the horizon, lending a distinct Front Range character to the experience.
Safety at Union Reservoir is taken seriously, with mandatory personal flotation devices and whistles for anyone on watercraft — a common precaution on state-managed lakes. Wind and weather can shift quickly; knowing conditions beforehand is essential, as the reservoir can become testing when storms roll in or winds rise. Though ranger presence is intermittent, the overall environment encourages self-responsibility on the water.
Whether you’re casting a line, balancing on a paddleboard, or cooling off in the designated swim beach, Union Reservoir offers accessible outdoor recreation in Longmont’s backyard. Its combination of sandy shoreline, open water, and pet-friendly spaces makes it a standout for anyone looking to combine active water sports with a laid-back Colorado vibe.
Wearing a PFD is required for all watercraft users here and enhances safety on the reservoir's open waters.
essential PriorityWinds and storms can sweep across the water quickly—check local forecasts and watch clouds carefully before heading out.
warning PriorityCarry a whistle to signal for help when needed; understand it may not guarantee immediate ranger assistance.
info PriorityHelp maintain the reservoir’s clean and accessible beaches by taking all trash with you upon departure.
info PriorityA must-have for safety on any watercraft here.
Required for signaling emergencies on the water.
Protect your skin during long exposure on open water and sandy beaches.
Protect feet on sandy and rocky entry points and shallow swim areas.
Spring brings moderate temps for water activities with fewer crowds, but chilly water and sudden weather shifts call for preparation.
Summer is peak season for recreation, combining warm weather with long days, though water quality dips late and safety regulations increase.
Fall offers a quieter reservoir experience with crisp air and active fishing, ideal for visitors seeking solitude and cooler conditions.
Winter closes down water recreation but supports chilly outdoor activities and quiet contemplation along the shore.
Yes, paddleboarding is permitted year-round, but water conditions and weather may limit use in colder months.
Yes, there is a designated dog beach area where dogs can swim and play off-leash.
All watercraft passengers must wear personal flotation devices and carry a whistle for emergency signaling.
Fishing is allowed, but anglers must have the appropriate Colorado fishing license and follow state regulations.
There is a lifeguard on duty only in the designated swimming beach area, but no lifeguards patrol the open reservoir.
Alcohol is not permitted within the reservoir area according to park regulations.
Watercraft in motionDistant foothills and mountain ridgesWildlife along the shore
Denver
easy
1–3 hours
Basic fitness required for paddleboarding or swimming; families and beginners will find access straightforward.
Union Reservoir has long served the Longmont area as both an irrigation resource and a recreational water body.
Experience Needed: This natural landmark is recommended for those with some outdoor experience.