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Union Reservoir - 0461 CR#26

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, wakeless boating, camping, windsurfing and picnicking. The Reservoir is located approximately 7 miles west of I-25. For additional information, call (303)772-1265.

FEES: Union Reservoir Fee Schedule | HOURS: Current Union Reservoir Hours | ACTIVITES: Union Reservoir Activities

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Main Picnic Area Reservations/Shelters

For a fee of $75.00 a day, you may reserve the main picnic area or the shelter for large groups - or small (additional gate fee per vehicle is required). There are picnic tables and barbecues set up in prime locations for your pleasure as well. 3.2% alcohol is permitted in the park with a permit. The fee for the alcohol permit is an additional $75.00


Quick link to reserving Union Reservoir Campsites online.Reserve campsites online

Primitive campsites are available to reserve on Friday and Saturday nights only. Choose from an RV or tent campground. Both sites are primitive: no water, no electricity. To reserve campsites online, access the availability calendar through the top search tab. Reservations can be made by calling the office at 303-772-1265, Monday thru Friday, 8:00 am to 5:00 pm.  Reservations cannot be made over the phone on weekends or Holidays.  All reservations must be made online during these times.


Sailing Club

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 go to


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