WSPP282

• File Number: 8240.200.39.C
• Description: Colorado River Threatened-Endangered - RIPRAP - CFOPS - Water Availability
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 3/1/2003
• Author: Brown and Caldwell
• Title: Phase 2 Coordinated Facilities Water Availability Study for the Endangered Fishes of the Upper Colorado River - Tech Memo Number 12 - Comments-Responses to 01-01-03 - Draft - 03-01-03
• Water Supply Pro - Doc Type: Report/Study

OO1l728

This group would have sufficient operating and management resources to determine when and how
much water should be released or otherwise made available from specific facilities.

2.3.5 Future Depletions

The Phase 1 report directed that: (1) sensitivity analysis will be used in a similar fashion with respect to
the 120,000 acre-feet per year of future depletions, and (2) at the conclusion of investigating each of
the alternatives in Phase 2, the alternative will be subjected to necessary and appropriate sensitivity
analysis to determine if feasibility of the alternative is affected by including the 120,000 acre-feet per
year of future depletions in the baseline hydrology.

The procedures followed in Phase 2 and the assumptions used for the sensitivity analysis include:

1. Increased average annual diversions from Dillon Reservoir via the Roberts Tunnel of
approximately 50,000 acre-feet per year based on a monthly demand schedule for the
study period provided byDenver Water (October 2, 2001 personal communication
from Steve Schmitzer to Bruce Rindahl).

2. An average of 12,000 acre-feet per year of additional depletions at the Adams Tunnel
node during April, May, June and July.

3. An average of approximately 1,000 acre-feet per year taken at Denver Water's existing
points of diversion under Denver's Water existing priorities in the Fraser River system
and conveyed via the Moffat Tunnel.

4. An average of 20,000 acre-feet per year of additional depletions to the Eagle River
from April IS-July 15 at the Homestake Reservoir node.

5. 14,000 acre-feet per year of additional depletions at a node on the Colorado River
immediately downstream from the confluence with the Roaring Fork. This water
would be diverted under a 1960 priority.

6. 14,000 acre-feet per year of additional depletions at the node at the head of the IS-Mile
Reach. This water would be diverted under a 1960 priority.

The sum of the above listed average annual additional depletions is approximately 110,000 acre-feet
per year. Note that the estimated future depletions from each entity were in total 1 0,000 acre-feet less
than the original estimate of 120,000 acre-feet.

.

2.3.6 Flow Targets

As indicated in: (1) a memo from the Service (Maddux, February 2,1999), (2) the RIPRAP action plan
(April 1, 1999) and (3) the Final PBO (U.S. Fish and Wildlife Service, December 20,1999, pg. 11), the
Service is first and foremost interested in augmenting the peak of the spring runoff hydrograph with
an additional 20,000 acre-feet of water on an average annual basis. The Service's priority is to increase
spring peak flows when the hydrograph peak is expected to be in the range of 12,900 to 26,600 cfs at

P:\Data \GEN\CWCB\19665\Repon Phase 2\FinalRepon12,02\Final_ Draft_ Repon(l-03) ,doc

21