WSP07002

• File Number: 8449
• Description: Platte River Studies
• State: CO
• Basin: South Platte
• Date: 2/1/1991
• Author: City of Greeley
• Title: Feasibility Study for Rehabilitation of Hourglass Dam and Reservoir Vol. 1
• Water Supply Pro - Doc Type: Publication

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GENERAL INFORMATION

LOCATION

The Hourglass Dam and Reservoir location is shown on the attached Vicinity Map, The map
shows the major features of the Greeley water supply system and Ihe principal cities In the area.
The dam and reservoir are In the Roosevelt National Forest in Larimer County. The City of
Greeley Is In Weld County on the plains east of the Rocky Mountains. The Cache la Poudre
River flows through Ihe City.

The Cache la Poudre River rises at Milner Pass in the Rocky Mountain National Park. some 65
miles west of Greeley, The river flows generally north Into the Roosevell National Forest and
then easl and sOUlheast to join the SOUlh Platte River aboUl three miles east of Greeley.

Hourglass Dam forms an off-channel reservoir Just sOUlh of Beaver Creek, aboUl one-half mile
east of Comanche Dam, It Is located aboUl nine miles sOUlh of Ruslic, Colorado in Larimer
County. Hourglass Dam has a very small drainage basin. Most of its water supply Is Beaver
Creek water released to Hourglass Reservoir from Comanche Dam through a feeder channel.

The 0,74 square mile Hourglass Dam drainage basin is 1.8 miles long and has a 0,41 mile
average width, Basin elevations range from 9,400 to 11,400 feel. The main channel slope Is
1,110 feet per mile,

CLIMATE

Greeley has a mild, sunny, semi-arid climate that prevails over much of the central Rocky
Mountain region. This equitable climate results from Greeley's location on the eastern plains
of the Rocky Mountains in an area of prevailing westerlies. It Is located far from any major
atmospheric moisture sources and is separated from the Pacifle Ocean sources by high
mountains. The c1imale is characteristically low in humidity, low in average precipitalion. and
sunny. There are an average of 325 sunny days per year.

Spring is the wettest, coldest and windiest season, Much of the early spring precipitation
occurs as snow, Summer precipitalion results largely from monsoon circulation Ihal brings

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