Water Management Study: Phase 1 Report

• File Number: 8461.100
• Description: Adaptive Management Workgroup
• State: CO
• Basin: South Platte
• Water Division: 1
• Date: 1/29/2008
• Author: Boyle Engineering, Ecological Resource Consultants, BBC Research & Consulting, Lytle Water Solutions
• Title: Water Management Study: Phase 1 Report
• Water Supply Pro - Doc Type: Report/Study

The results for each individual year are presented in Appendix 3. Appendix 3 presents the
total amount of Program water released from Lake McConaughy, the total Program water
reaching the Overton gage, the peak Program water delivery, and the period of release to
achieve the target flows.
The following results correspond to Table 3-8 and Appendix 3 for the target flow of
5,000 cfs of Program water for Cases I and II:
5,000 cfs Program water - Case I(Districts divert Program water):
. Pulse flows of 5,000 cfs of Program water are achieved for 19 of the 60 years of the
study period, about 1 in 3 years. However, peak flows in excess of 5,000 cfs occur
for only one day. The three day duration is not achieved. Of these 19 years, 10
occur in Average years and 9 occur in Dry years; the 5,000 cfs target is not
achieved in any of the Wet years of the study period.
• Average year classification- A peak flow of 5,000 cfs of Program water is
achievable in some years, for a duration of 1 day only, but on average is not met.
On average, the peak Program water flow at Overton is 4,700 cfs. The average
volume for the 3 day pulse flow is 22,200 ac-ft, and is 7,600 ac-ft less than the
target volume. This volume at Overton is achieved with a release from Lake
McConaughy of 81,300 ac-ft (in addition to a small volume of Tamarack I water).
• Wet years - A peak flow of 5,000 cfs of Program water is never achieved due to the
system being generally full. On average, the peak Program water flow at Overton is
3,800 cfs in these Wet years. The average volume for the 3 day pulse flow is 19,100
ac-ft, and is 10,700 ac-ft less than the target volume. This volume at Overton is
achieved with a release from Lake McConaughy of 71,600 ac-ft (in addition to a
small volume of Tamarack I water).
• Dry years - A peak flow of 5,000 cfs of Program water is achievable for 1 day in
some years, but not all years. On average, the peak Program water flow at Overton
is 5,200 cfs in these Dry years. The average volume for the 3 day pulse flow is
24,300 ac-ft, and is 5,500 ac-ft less than the target volume. This volume at Overton
B0vLE Page 33 of 58 January 29, 2008
PRRIP - Draft Water Management Study, Phase I