WSP12515

• File Number: 8220.102.01.H
• Description: Colorado River - Water Projects - Aspinall Storage Unit - General - Operation Studies
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 8/1/2003
• Author: LaGory - Tomasko - Hayse
• Title: Evaluating the Effects of Aspinall Unit Release Strategies on Endangered Fish Habitat in the Lower Gunnison River - Draft - 08-01-03
• Water Supply Pro - Doc Type: Report/Study

000322

;

Draft - Do Not Cite

August 2003

11 Number of days/year flows would exceed the threshold for scouring side channels
in the Gmmison River at the Grand Junction gage for six flow scenarios............................34

12 Number of days/year flows would exceed the threshold for removing sand and fines
in the Gmmison River at the Grand Junction gage for six flow scenarios............................35

13 Number of days/year flows would exceed the threshold for removing gravel
from pools in the Gmmison River at the Grand Junction gage for six flow scenarios .........37

14 Achievement of half-bankfull and bankfull flow thresholds under different

release scenarios.................................. .................................................................................. 39

15 Percent exceedance ofFWS instantaneous peak flow targets for
different release scenarios given 1975 through 2000 hydrology ..........................................40

16 Achievement of Milhous flow thresholds under different release
scenarios given 1975 through 2000 hydrology .....................................................................41

FIGURES

1 Historical release patterns (gage scenario) from 1975 through 2000 .....................................4

2 Release pattern for the Reclamation scenario given 1975 through 2000 hydrology ..............4

3 Release pattern for the Western scenario A (maximum peak:, existing ramp
rates, and 950,000 ac-ft spill trigger) given 1975 through 2000 hydrology ...........................5

4 Release pattern for the Western scenario B (maximum peak:, existing ramp
rates, and 900,000 ac-ft spill trigger) given 1975 through 2000 hydrology ...........................5

5 Release patterns for the Western scenario C (maximum peak, unlimited ramp
rate, and 950,000 ac-ft spill trigger) given 1975 through 2000 hydrology .............................6

6 Release patterns for the Western scenario D (10,000 cfs peak:, unlimited ramp rate,
and 900,000 ac-ft spill trigger) given 1975 through'2000 hydrology .....................................6

7 Historical mean daily flows (gage scenario) from 1975 through 2000..................................7

8 Flows for the Reclamation scenario given 1975 through 2000 hydrology .............................7

9 Flows for the Western scenario A (maximum peak, existing ramp rates, and
950,000 ac-ft spill trigger) given 1975 through 2000 hydrology............................................8

10 Flows for the Western scenario B (maximum peak, existing ramp rates, and
900,000 ac-ft spill trigger) given 1975 through 2000 hydrology............................................8

11 Flows for the Western scenario C (maximum peak, unlimited ramp rate, and
950,000 ac-ft spill trigger) given 1975 through 2000 hydrology............................................9

12 Flows for the Western scenario D (10,000 cfs peak, unlimited ramp rate, and
900,000 ac-ft spill trigger) given 1975 through 2000 hydrology............................................9

13 Sediment load relationships during the pre-peak and post peak: periods
on the Gmmison River near Grand Junction......................................................................... 13

14 Percent exceedance for mean daily flows at the USGS Gage on the
Gmmison River near Grand Junction under different Aspinall Unit release scenarios ........23

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