WSPC06079

• File Number: 8064.100
• Description: Ute Tribes
• State: CO
• Basin: San Juan/Dolores
• Water Division: 7
• Date: 6/1/1987
• Author: Boyle Engineering
• Title: Agricultural Engineering Study - Mancos Watershed - Task D-E - Final Report - Design-Cost Estimate for Off-Farm Irrigation Facilities and PIA Determination
• Water Supply Pro - Doc Type: Report/Study

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parcels could be served from the river without storage if an

acceptable shortage criteria were considered. All computer

operating simulations of the river were run on monthly time

increments for a 30-year historical period 1951 through 1980 using

the estimated virgin flows developed by W.W. Wheeler & Associates.

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The irrigation shortage criteria used by the u.s. Bureau of

Reclamation in their planning studies were adopted as the acceptable

criteria for this study. These criteria provide that the

accumulated shortages in the irrigation supplies delivered shall not

exceed the following proportions of the average annual irrigation

requirement:

o 50 percent in any single year,

o 75 percent in any two consecutive years, or

o 100 percent in any ten consecutive years.

The simulations for Case I consisted of operating a reservoir at Site

9 using the total virgin flows on the Mancos River below its

confluence with Weber Canyon (Point 17 on Figure D-ll) adjusted to

account for the estimated stream losses above Point 17 due to

phreatophytes. No 'adjustment to the virgin flows at Point 17 on

account of the additional drainage area between Point 17 and Site 9

was made since the incremental inflow was estimated to average only

0.5 percent of the flow at Point 17. During the irrigation months,

inflows to the reservoir were bypassed through the reservoir to the

extent required to meet first, the estimated stream losses due to

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