Fruitgrowers Dam

Overview

Fruitgrowers Dam, located on Alfalfa Run, is 3 miles north of Austin, Colorado. It is an earthfill, rock-faced structure, 55 feet high and 1,520 feet long, containing 136,000 cubic yards of material. The reservoir stores a total of 4,540 acre-feet of water. The spillway, located on the left side of the dam, is an uncontrolled structure (meaning flows aren't regulated). A 76-foot-long concrete-lined channel discharges into a stilling basin which slows the velocity and reduces the energy of the water. The outlet works consists of one 3-foot diameter pipe controlled by two slide gates.

Geology 

Bedrock at Fruitgrowers Dam is Mancos Shale of Cretaceous age. The Mancos Shale is a dark gray marine formation and has a gentle northerly dip in the vicinity of the dam. The shale is brown, soft, and has abundant secondary gypsum present when weathered. There is no evidence of faulting in the foundation area of the dam.

On the left abutment, the shale is covered with a thin layer of clay slope wash. The topography of this abutment suggests the presence of land-slide or slump deposits. Two inclinometers have all shown slight movements within the abutment. These inclinometers have all shown slight movement in a northwest direction at rates of 0.2 to 0.4 inches per year (0.5 to 1.0 cm/year). These movements are occurring at depths of 20 to 40 feet (6 to 12 m).

In the valley bottom, stream alluvium was found to be up to 23 feet (7 m) thick over Mancos Shale. This alluvium is composed of clayey and gravelly soils and contains some basalt cobbles and boulders.

The right abutment is a gently sloping area with deep glacial outwash deposits over the shale bedrock. These deposits were found to be up to 155 feet thick and contain gravel, cobbles, and boulders of basalt derived from the lava flows on Grand Mesa.

Readings of observation wells installed in 1979 indicate the presence of two ground water systems at Fruitgrowers Dam. One body of ground water occurs in surficial materials, and the second is confined water under pressure in the underlying Mancos Shale.


General
RegionFacilities in Upper Colorado | Upper Colorado Home Page
StateColorado
CountyDelta
ProjectFruitgrowers
Dam Type
ReservoirFruitgrowers
WatercourseAlfalfa Run
Location
Longitude-107.9545783996582
Latitude38.826669923445486
Original Construction1938-1939
Modified Construction
National ID NumberCO01683
Hydrologic Unit Code

Dimensions
Structural Height55.0 ft
Hydraulic Height (Normal Operating Depth at Dam)36.0 ft
Top Parapet (Elevation)
Spillway Crest Elevation5485.0 ft
Crest Elevation5493.0 ft
Crest Length1520.0 ft
Crest Width
Base Width
Volume of Dam Construction Materials136,000 cu. yards
Streambed at Dam Axis5453.0 ft
Top of Exclusive Flood Control Pool (Elevation)
Top of Joint Use Pool (Elevation)
Top of Active Conservation Pool (Elevation)5485.0 ft
Top of Inactive Conservation Pool (Elevation)
Top of Dead Storage Pool (Elevation)5460.0 ft

Hydraulics & Hydrology
Total Water Storage at Elevation
Maximum Water Surface Elevation5489.0 ft
Normal Water Surface Elevation
Spillway Type
Auxiliary SpillwayNo
Spillway Capacity at Elevation1680 cfs at 5490.0 ft
Auxiliary Spillway Capacity at Elevation
Uncontrolled Spillway Capacity at Elevation
Outlet Works Capacity at Elevation
Diversion Capacity at Elevation
Drainage Area12.0 sq mi
Hydrometeorological Report (HMR)HMR 49
Probable Maximum Flood (PMF) Report

Contact Information
Owner
TitleArea Office Manager
OrganizationWestern Colorado Area Office
Address2764 Compass Drive, Suite 106
CityGrand Junction, CO 81506
Phone (Office)970 248-0600
OperatorNo value defined


Last updated: Feb 20, 2009