Union Reservoir Nature Area

· St. Vrain

Union Reservoir Nature Area

Aliases: Calkins Lake

This large reservoir is one of the best places in the area to look for ducks, grebes, loons, and other waterbirds from fall through spring. Many rarities have shown up here, including Red-throated and Yellow-billed Loons, Ancient Murrelet, Hudsonian Godwit, and Little Gull. The reservoir is usually frozen in January and February; Clark’s and Western Grebes are reliable the other ten months of the year. The reservoir can be scanned fairly well from CR 26 on the south or from CR 28 on the north. A Longmont City Park on the southwest corner offers camping, picnic areas, and swimming in the summer. Fees apply in the city park – be sure to contact City of Longmont or visit their website for details.

County: Weld

Directions: From I-25: exit at CO 119, Firestone Blvd./Ken Pratt Blvd., go west 4 miles then head north on County Line Rd. To access the south side of the reservoir, head east on CR 26 to the parking lot. To access the north side, continue north on County Line Rd. and in 2.2 miles, go east on CR 28. Parking is along the road.

Dates of Access: Open all year, walk-in access only from November 1 to February 28
Hours: Daylight hours
Ownership: Municipal/Private
Admission: Daily fee or annual pass; Colorado residents with current Disabled Veterans License Plates may enter Union Reservoir for free. The veteran must be present in the vehicle.

Restrictions: Please obey all rules and regulations in the city park, and respect private property

Parking: Roadside, and paved parking lot
Lodging: Hotels in Longmont.

Handicapped Access: Viewing from car

Latitude: 40.172171
Longitude: -105.044469

» Visit the website for Union Reservoir Nature Area

» Explore eBird Hotspot for this site


Drinking FountainYes
Gravel TrailsNo
Paved TrailsNo
Visitor CenterNo
Gift ShopNo

Share This Watchable Wildlife Site!