Union Reservoir is a 736-acre body of water providing many outdoor recreational activities. Originally called Calkins Lake, the reservoir was carved out during the last glacial age and is one of only a few natural lakes in Colorado. In 1903, the Union Ditch Company began drilling a tunnel to release water into the St. Vrain River. According to Colorado water law, that made Union a true reservoir. Today, visitors to Union Reservoir can enjoy fishing, swimming, paddleboarding, wakeless boating, camping, windsurfing and picnicking. The Reservoir is located approximately seven miles west of I-25.
Mandatory boat inspections are required before launching. Inspections hours are from 7 a.m to 7 p.m. daily.
Please contact the Union Reservoir Office for current information.
Paddleboard & Kayak Rentals
Union Sailing Club is one of Colorado’s largest and most active sailing clubs with weekly racing in the spring, summer and fall. Several regattas, social events, youth activities and clinics open to the general sailing public are also hosted each year. Instruction is also offered. Club boats are available on a limited basis for rental to experienced sailors. For more information, please visit the Union Sailing Club website.
The facility is open for camping the first Friday in May and ends for the season on the last Saturday in October. There are 28 designated RV sites that overlook the picturesque reservoir and 14 tent sites that are located close to the swim beach and playground. Camping is available only on Friday and Saturday nights but is extended on holiday weekends (Memorial Day, 4th of July and Labor Day). Please note: Reservations are non-refundable, check-out time is noon and alcohol is prohibited. Camping reservations can be made here.
A dog-friendly beach is located on the south side of the reservoir. Dogs are allowed off leash and may swim in this designated area. Dogs must be leashed in all other areas of the park.
The Reservoir is fast becoming one of Colorado’s finest walleye fisheries. Walleye 17-24 inches are common. In recent years, Union Reservoir has become the hotspot for fly fishermen who enjoy the thrill of catching the hard-fighting carp. In addition, a healthy population of trout, crappie, catfish, bass, sunfish, wiper and tiger muskie provide a quality fishing experience. Fishing is available along the majority of the shoreline or from a boat. Colorado fishing regulations are enforced and a fishing license is required. A fish cleaning station and handicapped accessible fishing pier are provided for your convenience.
Numerous picnic sites with a table and grills are located throughout the park. Both group and individual sites are available on a first come, first served basis. For a fee of $75 a day, you may reserve the main picnic area or the shelter (additional gate fee per vehicle is required). There are picnic tables and barbecues set up in prime locations for use as well. Beverages up to 3.2% alcohol are permitted in the main picnic area or the shelter with a permit. The fee for an alcohol permit is an additional $75. For online shelter reservations, click here.
Union Reservoir’s sandy beaches provide a gathering spot for young and old alike. Lifeguards are stationed at the beach for safety. Swimming is allowed during posted hours only. A sand volleyball court, picnic shelter and playground are located near the beach for your enjoyment. Temporary loading and unloading is permitted along the beach for easy access, with parking in the paved lot.
One of the best windsurfing spots in northern Colorado! Easy water-front access with great conditions creates a windsurfer’s paradise.
Daily vehicle fee – $8
Trailered Boat – $8
Bicycle/Walk-in – $2 per person
Camping (without season pass) – $12 + daily vehicle fee
Annual Pass – $60/resident, $75/non-resident
Colorado Disabled Veterans (with current Disabled Veteran license plate) – Free
March 1 – April 30 – 7 a.m. – 7 p.m.
May 1 – Labor Day – 6 a.m. – 9 p.m.
September 6-30 – 7 a.m. – 8 p.m.
October 1-31 – 8 a.m. – 5 p.m.
November 1- February 28 – Sunrise-Sunset (Walk-ins only, daily admission fees apply)
For swim beach and open water hours, please click here.