Reservoirs

Longmont & Ralph Price Reservoirs

Button Rock Preserve is located in a quiet river valley about 7 miles west of Lyons. Within this walk-in only preserve you will find Longmont and Ralph Price Reservoirs along the North Saint Vrain Creek. Longmont manages this natural watershed and reservoirs to preserve the resource and provide storage for the City’s water utility.

The preserve creates a unique experience for visitors, providing opportunities to view wildlife, the natural environment, and water management facilities at a close level.

More information about recreation in the preserve is available on the Button Rock Preserve web page.

Union Reservoir

Union Reservoir was constructed “on top of” a natural lake called Calkins Lake. It 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. It was a natural depression that was presumably deepened and enlarged over time by bison herds that used the natural low spot for watering and wallowing in. 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.

Planned Enlargement of Union Reservoir

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.

In order to preserve the ability to enlarge Union Reservoir in the future, the 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.

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, Open Space and Trails leases 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, please see the Union Reservoir Park web page.