10825 Water Supply Alternative Summary Phase 2 Assessment January 2008 Draft

• Description: A report from the Grand River Consulting Corporation on alternatives for delivering 10,825 AF of water to the 15-mile reach of the Colorado River.
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/2008
• Author: Grand River Consulting Corporation
• Title: 10825 Water Supply Alternative Summary Phase 2 Assessment January 2008 Draft
• Water Supply Pro - Doc Type: Report/Study

8.5 LAKE GRANBY AND RUEDI RESERVOIR PAIRED WITH OMID IMPROVEMENTS (C8)
In this alternative, releases from three existing reservoirs provide the 10825 Water:
a) Lake Granby would supply releases of 2,700 acre -feet in all years.
b) Green Mountain Reservoir HUP surplus water available to the Recovery Program would
increase with efficiency improvements to the Orchard Mesa Irrigation District (OMID)
irrigation system. For purposes of this study, and based upon the January 2008 report by
California Polytechnic State University, we have assumed that at least 5,412 acre feet of
additional Green Mountain Reservoir water would be available in almost every year. During
infrequent critically dry years (such as 1977 and 2002), the OMID improvements may not
provide any water, as a Green Mountain HUP surplus may not occur in these years.
c) Ruedi Reservoir would provide the balance of the 10825 Water. A total of 2,700 acre feet
of water would be released in almost every year. During infrequent dry years such as 1977
and 2002, a total of 8,125 acre feet of Ruedi water would be released.
This alternative would not construct any new reservoirs or diversion facilities. The only
structural facilities would be associated with irrigation efficiency improvements to the OMID
system. Any alternative using OMID water may be predicated upon the implementation of
forecasting and operational procedures to allow the release of Green Mountain Reservoir HUP
surplus water earlier in the year. If Green Mountain HUP surplus is only available late in the
year, this alternative may not provide adequate 10825 Water in July and August.
This alternative meets both primary and some of the secondary objectives of the study. Lake
Granby releases will substantially improve aquatic habitat in the upper Colorado River. Also, the
reduced releases from Ruedi Reservoir will minimize the potential for adverse effects to the
Fryingpan River (more than any other alternative involving Ruedi Reservoir) for several reasons.
First, Ruedi releases will only exceed 2,700 acre feet per year in critically dry years. In these very
dry years when up to 8,125 acre feet of water will be released, the native runoff in the
Fryingpan River is already reduced, and additional releases from storage do not commonly cause
the flow of the river to exceed 300 cfs. Second, the increased releases will occur infrequently
(perhaps less than 10 % of the years) and will not result in sustained impacts to the Fryingpan
fishery.
It should be noted that neither the viability of Lake Granby as a source of 10825 Water, or the
implementation plan for OMID improvements are known at this time.
0825 Water Supply Study Phase 2 Alternatives Assessment January 2008 Draft 19