WSP12642

• File Number: 8210.215
• Description: Colorado River Basin Organizations-Entities - Colorado River Workgroup
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/3000
• Author: James S Lochead
• Title: Outline of the Law of the Colorado River - James S Lochhead - Date Unknown Briefing paper
• Water Supply Pro - Doc Type: Report/Study

OOD837

Comparison of Consumptive Uses, Losses, and Water Supply
1922 vs. Present
Colorado River Mainstem
(Values in Million Acre-Feet per Year)

1922 Present
Reconstructed average virgin flow at Lee's Ferry 18.41 15.02
Long term reconstructed average 13.53
Lowest reconstructed ten-year period 9.73
Lowest ten-year period of record 11.82
Lower Basin tributary inflow 2.11 1.44
Total available water supp(v-(Mainstem) 20.51 11.1-16.4
Upper Basin Uses 2.55 3.76
Upper Basin Reservoir Evaporation --- 0.56
Total Upper Basin Uses 2.5 4.2
Lower Basin Mainstem Uses 2.67 7.58
Lower Basin Reservoir Evaporation --- 1.89
Total Lower Basin Mainstem Uses 2.6 9.3
Delivery to Mexico and Welton-Mohawk bypass 1.6
Total Mainstem Uses 6.1 15.1

For the period 1903-1922. This was the amount reported by Delph E. Carpenter in his Historical Memorandum In Re
Colorado River, and Brief of Law of Interstate Compacts, June 4, 1921, at hearing on H.R. 6821, Judiciary Committee, Colorado House
of Representathes. In his Comments to Congress on the Colorado River Compact, Commissioner of Reclamation Arthur Powell Davis
estimated the reconstructed flow at 18.1 maflyr. ConI!. Rec., January 30, 1923, pp. 2713-2717.
2 Long term average for the period 1906-1996. Critical ten-year averages for the periods 1931-1940 and 1954-1963. Forty-
Eighth Annual Report of the Upper Colorado River Commission, Salt Lake City, Utah, Septermer 30, 1996. For the twelve-year period
1953-1964, the average annual virgin flow at Lee=s Ferry was only 11.6 maf.
l Tree ring analysis. The lowest ten-yearreconstructed record was for the period 1584-1593.
As used by the Lower Colorado Region, Bureau of Reclamation, informal communicatiOl.
Report of Delph E. Carpenter, December 15, 1922.
Upper Colorado River States Depletion Schedule, 1994. Upper Colorado River commission.
Comments to Congress on the Colorado River Compact, Commissioner of Reclamation Arthur Powell Davis, ConI!. Rec.,
January 30, 1923,pp. 2713-2717.
8 The Estimate of 1997 Colorado Water Use, U.S. Bureau of Reclamation, April 30, 1997, estimates total Lower Basin
mainstem use of 8.0maf for 1997. However, 19997 is a year of declared surplus. Under a normal year, Lower Basin main stem uses are
limited to 7.6 maflyr.
9 The Bureau of Reclamation Consumptive Uses and Losses Report, 1981-1985, shows total Lower Basin reservoir
evaporation of about 1.0 maf/yr. However, current accounting of the Lower Colorado Region of the Bureau of Reclamation estimates
1.8 maf/yr., informal communicatiOl.

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