Visit our Coronavirus page to stay up-to-date on the latest information and resources. ALL IN-PERSON CITY PROGRAMS AND EVENTS ARE CANCELLED UNTIL FURTHER NOTICE. See current closure details.

Información sobre la enfermedad del Covid-19



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.
  • Swimming with limited capacity. Fifty residents a day will be allowed on the swim beach per day, based on a first-come, first-served basis.

  • Open Water Swim
  • Moonlight Paddleboarding
  • 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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