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Union Resevoir Project

Sunset at Union ResevoirUnion Reservoir, formally known as Calkin's lake, is located approximately 3 miles east of Longmont on Weld County Road 26. Like most reservoirs along the front range of Colorado, Union Reservoir was built to supplement irrigation water supplies. Water from the reservoir is primarily used to irrigate farms along the South Platte River south of Greeley, Colorado. The Union Reservoir Company, which is a private irrigation company, owns the land inundated by the reservoir along with an additional 90 acres of dry land surrounding the Reservoir. Included in this 90 acres is a perimeter buffer that is an average of 50 foot in width.

Through the purchase of shares in Union Reservoir and through the transfer of shares to the City as a result of the Raw Water Requirement Policy, the City has become the majority owner of the shares of Union Reservoir. Currently, the City owns 85% of the shares in the Union Reservoir Company.

In 1986, the City of Longmont applied for and subsequently received a conditional decree for the enlargement of Union Reservoir. The proposed enlargement will increase the reservoir from its current 12,000 acre feet capacity an additional 20,000 acre feet to a total of 32,000 acre feet. The increased capacity in the Reservoir would provide the City with additional water storage capacity, better water exchange possibilities, and storage space for reuse water. Local area residents will benefit by having a reservoir that will have a greater surface area and there will be less water fluctuation per acre foot of water released along with providing additional recreational opportunities.


Property Acquisition

In order to preserve the ability to enlarge Union Reservoir in the future, he first step in the enlargement project is the acquisition of the property needed for the enlargement of the Reservoir. The purpose for purchasing this property is to preserve the ability to enlarge Union Reservoir in the future. In 1996, the City of Longmont City Council approved a land acquisition and finance plan for the purchase of property around Union Reservoir. This process is estimated to take from 10 to 20 years. Property is currently being purchased on a willing seller/willing buyer basis. The City has purchased approximately 265 acres of property of purchased a number of parcels around the reservoir (see map).


Land Management

In accordance with the land management plan that was adopted by City Council, land that is purchased by the City is being leased for agricultural purposes. All access to the reservoir is from the main recreation entrance on Weld County Rd. 26.


Recreation on Union Reservoir

The City of Longmont Parks and Recreation Department leases the recreation rights from the Union Reservoir Company. Property leased by the City adjacent to Union Reservoir does not provide access to the reservoir. All public access to the reservoir is through the main entrance located on Weld County Road #26. For additional information concerning recreation opportunities on Union Reservoir please visit the City of Longmont Parks and Recreation web site at or call (303) 772-1265.

For more information please contact the City of Longmont Water Resources at (303) 651-8376.

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Public Works & Natural Resources
Water Resources & Environmental Services
1100 S. Sherman St.
Longmont, CO 80501
Phone (303) 651-8376
Fax (303) 651-8812
Water Resources|Water Utilities|Public Works & Natural Resources|City of Longmont
This site was updated August 16, 2013
City of Longmont Public Works & Natural Resources Department
Water Resources & Environmental Services