WSP06594

• File Number: 8200.766
• Description: Gunnison River General
• State: CO
• Basin: Gunnison
• Water Division: 4
• Date: 3/9/1994
• Author: John Ozga
• Title: East River Inflows - Introduction
• Water Supply Pro - Doc Type: Data

30~ 4 71

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c.u. rates) and/or supporting information covering cropping
pattern, climate data, incidental use, etc., assumptions
applied in depletion development. They would like to use
these rates for the next Beta test and final model releases.

USBR Denver Office personnel have provided depletion rates
with incidental use and shortage adjustments removed (See
Table i.). Plots of annual consumptive use rates (' 52-
'90;adjustments removed) for the Upper Uncompahgre, Lower
Uncompahgre, Lower Gunnison, and smith Fork/North Fork areas
are shown on Figures 5-8.

During the first beta testing period, one of the testers
questioned the apparent upward trend in Lower Gunnison
depletion rates (see Figure i.). This trend is not apparent in
the "adjustments removed" rates (Figure ji).

A drop appears in both adjusted and "adjustments removed"
rates for the Upper Uncompahgre area (Figure .1, Figure .2)
beginning in 1981.

Documentation for the development of irrigated agriculture
conscumptive use as provided by the Denver Office (USBR) is
included in section H.

.

Review of documentation shows that consumptive use estimates
for the 1952-1990 period were developed as part of five
efforts:

1952 - 1974: CRSS

1975 - 1985: 1971-1975 CU&L report
1976-1980 CU&L report
1981-1985 CU&L report

1986 - 1990:

methods as outlined in Methods Manual and
Plan of Studv for the Colorado River
Svstem. Consumptive Uses and Losses
Report. 1985-90

The drop in Upper Uncompahgre consumptive use rates
observed in 1981 may be due all or in part to the change
in climate station data used in computations from
Montrose and Ouray to Ridgway in 1981.

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