Quick Info
Location: Northeast Longmont. Size: 736 acres. Activities: Swimming, paddling, fishing, sailing. Season: Memorial Day to Labor Day for swimming. Fees: Daily or annual passes required.
Union Reservoir is Longmont's summer destination - a large lake with a swim beach, boat ramp, and mountain views. Unlike many Front Range reservoirs that prohibit water contact, Union allows swimming in a designated beach area. It's the closest thing to a beach day without driving to the mountains or Nebraska.
Swimming
The swim beach is the main draw for families. A designated swimming area with a sandy beach offers supervised swimming during summer months. Lifeguards are on duty during peak season.
Beach features:
- Sandy beach area
- Designated swim zone with buoys
- Restrooms and changing areas
- Picnic areas nearby
The water is clean but typical reservoir quality - not crystal clear. Water temperature warms through summer but remains refreshing.
Paddling & Boating
Non-motorized: Kayaks, canoes, paddleboards, and sailboats are popular. The reservoir's size provides room to spread out. Bring your own or rent nearby.
Motorized: Power boats allowed with restrictions. Wakeless zones near swimming areas. Check current regulations before launching.
Boat ramp: Public ramp available. Can get busy on summer weekends - arrive early for easier launching.
Fishing
Union Reservoir offers decent warm-water fishing. Species include:
- Largemouth bass
- Walleye
- Channel catfish
- Bluegill and crappie
- Wiper (hybrid striped bass)
Shore fishing available around much of the reservoir. Boat fishing provides access to deeper water. Colorado fishing license required.
Planning Your Visit
Fees: Daily passes or annual permits required. Longmont residents get discounted rates. Purchase at the entrance or online in advance.
Hours: Seasonal hours vary. Generally sunrise to sunset. Swim beach has more limited hours during lifeguard season.
Facilities: Restrooms, picnic shelters, boat ramp, and parking lots. Some picnic shelters available for reservation.
Pets: Dogs allowed in some areas but not on the swim beach. Check current pet policies.
Best times: Weekday mornings are least crowded. Summer weekends and holidays can be very busy - arrive early for parking.
The Setting
Union Reservoir sits on the plains with views of the Rocky Mountain front range to the west. On clear days, Longs Peak dominates the horizon. The combination of water and mountain views makes for pleasant scenery, especially at sunset.
Frequently Asked Questions
Can I swim anywhere in the reservoir?
No, swimming is only allowed in the designated beach area when lifeguards are on duty during summer months.
Can I bring my own paddleboard or kayak?
Yes. Inspection may be required to prevent invasive species transfer. Check current launch requirements.
Is there food available?
Limited concessions during peak season. Bring your own food and drinks for a full day.
How does it compare to Boulder Reservoir?
Similar concept - both are plains reservoirs with recreation. Union is slightly smaller but often less crowded. Both have swim beaches.