PROJ00553

• Contract/PO #: FS0022X
• Contractor Name: West Anvil Water & Power Company
• Contract Type: Loan
• Water District: 0
• County: Garfield
• Loan Projects - Doc Type: Feasibility Study

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E. HYDROLOGY AND CLIMATOLOGY
1. Drainage Area Description
The drainage area upstream from the project site encompasses an
area of 6,983 sq mi. Of this area, approximately 2,800 sq mi
are above an elevation of 9,000 ft. The western portion of the
contributory area is composed of plateau and canyon lands with
deep-cut waterways; the eastern region is an area of valleys
bordered by high mesas ranging in elevation from 7,000 to
11,000 ft. Elevations decline gradually from east to west to
the project site.

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2. Climatology
Within the project drainage area, the climate varies from semi-
arid to alpine with pronounced differences in temperature and
precipitation due to the varying topography. The mountains of
Central and Western Colorado are a barrier to the movement of
warm moist air from the Gulf of Mexico. Because of this, the
predominant source of moisture to areas west of the Continental
Divide is the Pacific Ocean. Summer thunderstorms occur with
relative frequency, but without the intensity or areal distribu-
tion of those storms common to the plains of Eastern Colorado.
General rainfall, characterized by lesser intensity but greater
areal extent than convective-type storms, may occur over large
areas from late spring through late fall.

Within Garfield County, summers are characteristically cool with
moderately severe winters, especially in the mountainous
regions. The easterly movement of frontal systems through the
region produces rapidly changing local weather conditions.
Temperatures vary from 900F in the summer to below freezing in
the winter, with lows around -200F at the higher elevations.
Terrain elevation has a considerable effect on average annual
precipitation, with 10 to 15 in. in the river valleys, and 30 to
40 in. in the mountainous headwater regions.

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