Visit our coronavirus page to stay up-to-date on the latest information and resources. Safer at Home Orders are in effect. All City programs and events are cancelled through May 31. See current closure details.



Union Reservoir currently remains open to the public, with these restrictions:

  • Six-foot social distancing requirements and maximum group size of 10 is in effect.
  • Visitors should have a face covering available for times when it is not possible to maintain the six-foot social distancing.


  • Wakeless boating, canoeing, kayaking and paddleboarding are currently permitted.
  • Boat inspections are available between 8 a.m. and 5 p.m. daily. Please remain in your vehicle while your boat is being inspected.


  • Swim beach
  • Dog beach
  • Fishing pier
  • Playground
  • Shelter

Season passes for Longmont residents are available for purchase online (with proof of a Longmont utility bill), and senior discounts are available to those who qualify. (Non-resident Season Passes are not currently available.) Daily passes are also available at the entrance gate.

View fee schedule and link to purchase resident season passes. 


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 Creek. According to Colorado water law, that made Union a true reservoir.

The Reservoir is located approximately 7 miles west of I-25.

Find Out More


Special Events

Fees and Hours

Union Reservoir as a water supply resource for Longmont

Future enhancement plans for Union Reservoir recreation & complementary trail

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