WSP05690

• File Number: 8407
• Description: Platte River Basin - River Basin General Publications
• State: CO
• Basin: South Platte
• Water Division: 1
• Date: 1/1/1978
• Author: Toups Corp
• Title: Water Resources Investigation in the South Platte River Valley - Reach Number 2
• Water Supply Pro - Doc Type: Report/Study

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of recharge, a condition of overdraft is said to exist.

Overdraft is apparent when the water table throughout the

aquifer exhibits a long-range decline.

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The geohydrologic
and the adjoining
reviewed herein.

character of the South Platte River Valley

valleys of its major tributaries will be

Geologic cross-sections are presented on

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Figure 2-1.

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SOYTH PLATTE MAIN-STEM AQUIFER

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The South Platte valley fill deposits are approximately 5 miles

wide near Greeley, where the South Platte and Cache la Poudre

vaQleys merge. Downstream from Greeley, the South Platte Valley

gradually narrows to a width of 3 miles at Kuner. In its thickest

parts, alluvial deposits reach a maximum depth of 125 feet.

Production rates of up to 2,000 gpm are attained by production

wells. Specific capacities range up to 100 gpm/ft. USGS has

estimated the coefficient of storage of the valley fill

aquifer in this reach to be 0.2, based on representative alluvial

material and several pumping tests [Smith, et al., 1964].

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The South Platte Valley in the reach from Greeley to Kuner is

underlain by consolidated sedimentary rocks which overlie

Precambrian, crystalline rocks. The lower aquifer of this area

is formed by the sedimentary rocks. The principal formations

which comprise the deep aquifer system are the Fox Hills sandstone

and the Laramie. Both are extensive, and underlie the entire

ar~a. Representative thicknesses of the Fox Hills sandstone

formation and the Laramie formation are 250 feet and 650 feet,

respectively.

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