PERMFILE54772

• Permit No: M1979191
• IBM Index Class Name: Permit File
• Doc Date: 3/13/1980
• Doc Name: Hydrologic Impacts
• From: GEOLOGIC RESOURCES INVESTIGATIONS & DEVELOPMENT
• To: LARIMER CNTY
• Media Type: D
• Archive: No

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Hytlrogeology Geology for Lend Um Planning Environmental Geology
March 13, 1980
Board of County Commissioners
Larimer County Courthouse
Fort Collins, CO 80521
Dear Commissioners:
I have been retained by The Three Bells Ranch Associates to investigate the potential
hydrologic effects of their proposed sand and gravel quarrying operation NW of Windsor,
Colorado. Specifically, I have been asked to evalute the possibilities for detrimental
effects on irrigation rights and water wells in the immediate area of the proposed quarry
sites.
As part of my investigation, I have rev iewed data from the Colorado State Engineer's
office on registered water wells in the area; the report of Empire Laboratories on the
proposed gravel extraction sites, including test hole data; and studied topographic and
geologic maps of the area. In addition, I have interviewed personnel at the Colorado State
Engineer's office regarding water rights requirements for proposed sand and gravel opera-
tions and I personally have visited the proposed gravel quarry sites to visually inspect
the area.
The following observations and conclusions are based upon my evaluation of the above
mentioned information:
1. The principal hydrologic consequence of the proposed gravel operation is -
the increased evaporative losses of ground water which will be exposed to
the atmosphere in the quarry pits. Assuming that the maximum area of
quarry pits eventually totals 171 acres, the consumptive use of water due
to evaporation could be on the order of 500 acre-feet per year. Since
the natural water table in the vicinity of the proposed pits is generally
less than 5 feet deep, however, existing evapo-transpirative losses of.
ground water may approach that of direct evaporation. Therefore, the net
consumptive loss of ground water due to the increased evaporation from
open pits may be less than 200 acre-feet per year.
If water is used for washing operations at the pits, consumptive use rates
would be somewhat higher.
2. Approximately 20 water wells are located in the vicinity of the proposed
gravel pits (as reported in the Colorado State Engineer's records).
Virtually all of these wells are situated more than 1000 feet away and/or
up-gradient from the proposed pits.
P.O. e0X 2083 /FORT COLLINS, COLORADO 80521 /PHONE [phone]