City Of Greeley
Greeley's Water Resources Map

Water Supply

The City has numerous water rights in four river basins the Upper Colorado River, Cache La Poudre, the Big Thompson and Laramie River Basin. The Water Resource staff must account for all of this water and comply with the rules of the Colorado Water Court and the State Engineer’s Office, which is in charge of allocating all of Colorado’s water resources. Approximately one-third of the City’s water supply comes from agricultural water rights. These water rights must be formally changed to municipal use by a special legal process through the Water Court. In this court, the Water Resource staff and attorneys also defend the City’s water rights against adverse claims from other parties.

Greeley plans for and anticipates adequate water supply for a 1 in 140-year drought lasting 5 years.

Water Sources

For maximum drought protection, Greeley water comes from Rocky Mountain snowmelt feeding four rivers.

  • The Big Thompson River Basin is west of Greeley and originates in Rocky Mountain National Park.

      • In 1961, Greeley began accepting shares of the Greeley- Loveland Irrigation Companies system. GLIC is comprised of three interrelated companies:
        • Greeley-Loveland Irrigation Company (Boyd Lake)
        • Loveland and Greeley Reservoir Company (Lake Loveland)
        • Seven Lakes Reservoir Company (Horseshoe Reservoir)
      • GLIC System supplies are treated at the Boyd Lake Water Treatment Plant. Boyd WTP is used as a peaking source for Greeley from April to October.
  • The Cache La Poudre River basin stretches from Greeley into the mountains and national forest north and west of Fort Collins all the way to the Continental Divide at Cameron Pass.

      • Greeley owns six high mountain reservoirs on the Poudre River, Barnes Meadow, Comanche, Hourglass, Peterson Lake, Milton Seaman, and Twin Lakes that collect the spring snow melt for distribution throughout the year.

      • Greeley also owns non-potable water rights and gravel lake storage in the Lower Poudre Basin that are unable to be used at the water treatment plants.

      • Greeley owns shares in the Water Supply and Storage Company.

  • Greeley receives water from the Upper Colorado River Basin through two interrelated water projects: Colorado-Big Thompson and Windy Gap projects. These projects’ transmountain diversions greatly enhance Greeley’s water management flexibility and future options. Water from them can be delivered to either the Bellvue or Boyd Lake treatment plants.

      • The Colorado-Big Thompson Project, administered by the Northern Colorado Water Conservancy District, diverts water from the Colorado River on the Western Slope through the Adams Tunnel to water users on the eastern plains. Greeley has rights to about 7 percent of the C-BT water.

        • The C-BT Project delivers an annual average of 213,000 AF and provides supplemental water to 30 cities and towns.

        • The C-BT Project is made up of 12 reservoirs, 35 miles of tunnels, 95 miles of canals and 700 miles of transmission lines.

      • Greeley has a substantial ownership of Windy Gap project, a supplement to the C-BT system.

        • Windy Gap consists of a diversion dam on the Colorado River, a reservoir, a pumping plant and a six mile pipeline to Lake Granby.

        • Six cities cooperated to develop Windy Gap. Now there are 13.

        • The Municipal Subdistrict of the NCWCD is working on the Windy Gap Firming Project (WGFP) to improve the firm yield from the existing Windy Gap supply. Greeley has committed to purchase 7,000 AF of the proposed 90,000 AF Chimney Hollow Reservoir, the preferred alternative of WGFP.

  • Greeley's 2006 acquisition of the Laramie-Poudre Tunnel is operated by the Tunnel Water Company. Greeley receives water from the Laramie River basin through transmountain diversion projects. The Laramie River basin originates northwest of Fort Collins and flows north out of Colorado to the North Platte River in Wyoming.

      • The historic Tunnel Water Company was formed in the early 1900s to facilitate the transfer of Laramie River water into the Poudre River Basin . The diversion required construction of a tunnel beneath a mountain divide. The outlet is visible along Colorado Highway 14 in the Poudre Canyon . The tunnel was completed in 1921.

      • The Water Supply and Storage Company and Windsor Reservoir and Canal Company own all the shares in the TWC. The City of Greeley partnered with North Weld County Water and Fort Collins-Loveland Water District to purchase shares in the TWC.

      • The City’s share of the yield from the Laramie-Poudre Tunnel will be 1,110 acre feet.

  • Stock ownership in various irrigation companies.

High Mountain Reservoirs

A reservoir is a pond, lake, or basin, either natural or artificial, used for the storage, regulation, and control of water. Greeley owns six high mountain reservoirs on the Cache la Poudre River that collect the spring snowmelt for distribution throughout the year.

Greeley purchased the Mountain and Plains Irrigation Company in 1947 for $190,000. Mountain and Plains assets included Barnes Meadow Reservoir, Peterson Lake Reservoir, Big Beaver (Hourglass) Reservoir, Comanche Reservoir, Twin Lakes Reservoir and the Bob Creek Ditch.

By the mid 1980s, all of the old reservoirs were under fill restrictions and several under the State Engineer’s Office breach or repair orders. Between 1990-1998, Greeley spent $10.25 Million on repairs or replacement. Today, all of Greeley’s reservoirs are in excellent condition.

Milton Seaman Reservoir
  • Built: 1941
  • Storage: 5,008 acre-feet
  • Elevation: 5,478 feet
  • Dam height: 115 feet
  • Proposed enlargement date: 2029
  • Proposed storage: 53,000 acre-feet

The City voluntarily restricted filling the reservoir after 1983 due to spillway deterioration. The spillway was rehabilitated in 1996 for a total of $3.42 million. This included construction of a new labyrinth spillway, remediation of a 43,396 cubic yard landside and placement of 9,877 cubic yards of dental concrete.

The City is partnering with other area municipal and agricultural water providers to develop a regional water management project involving Seaman Reservoir and Fort Collins' Halligan Reservoir. The project currently in the permitting stage, will provide additional water to satisfy future demand and drought protection. City leaders anticipate the regional partnership also will help the affected communities more efficiently use existing water supplies.

Seaman Reservoir Hiking Map (pdf)

Barnes Meadow Reservoir
  • Built: 1922
  • Storage: 2,349 acre-feet
  • Elevation: 9,094 feet
  • Dam height: 47 feet

The reservoir was under a fill restriction from the State Engineer’s Office prior to 1991. In 1992, the dam was rehabilitated for a total of $511,000. This included relining the dam outlet, replacing the primary & secondary spillways, and installing a toe-drain system. A SCADA system was installed in 2005.

Peterson Lake Reservoir

  • Built: 1922
  • Storage: 1,183 acre-feet
  • Elevation: 9,492 feet
  • Dam height: 38 feet

The reservoir was under a fill restriction from State Engineer’s Office prior to 1985. In 1995 and 1996, the dam was rehabilitated for a total of $1.732 million. The work included replacement of the embankment dam with a new roller compacted concrete dam, a new outlet and spillway, construction of a new saddle dam, and removal of the emergency spillway. A SCADA system was installed in 2005.

Comanche Reservoir
  • Built: 1924
  • Storage: 2,628 acre-feet
  • Elevation: 9,401 feet
  • Dam height: 46 feet

Prior to 1990, the State Engineer’s Office issued a directive to drain, breach or rehabilitate the dam. It was rehabilitated from 1990-1991 for a total of $1.75 Million. This included installation of filter blanket and toe drain system, deactivating the emergency spillway, installing a roller compacted concrete spillway, raising the dam for the required probable maximum flood freeboard and installing new outlet works. In 2002, a SCADA system was installed. In 2005, dam toe drain section was repaired and hydraulics were installed on the gate structure.

Hourglass Reservoir

  • Built: 1898
  • Enlarged: 1901
  • Storage: 1,693 acre-feet
  • Elevation: 9,070 feet
  • Dam height: 45 feet

Reservoir was under a fill restriction from the State Engineer’s Office for more than 20 years. The dam was rehabilitated in 1996 for a total of $278,000. This included installation of a filter blanket and toe drain system, deactivation of the emergency spillway, placement of a new concrete spillway control structure and rip rap. A new SCADA system was installed in 2002.

Twin Lakes Reservoir

  • Built: 1924
  • Storage: 278 acre-feet
  • Elevation: 9,295 feet
  • Dam height: 35 feet

The state engineer placed the reservoir on a zero fill or no storage allowed restriction in 1982. The City was required to weld the release gate open. The reservoir was rehabilitated in 1998 for a total of $1.08 million. The original dam was replaced with a zoned-earth embankment structure; new outlet works and a concrete grade berm were constructed.