BOARD01217

• Board Meeting Date: 5/24/1999
• Description: WSP Section - Colorado River Basin Issues - Upper Colorado River Commissioner's Report - Outline of the Law of the Colorado River
• Board Meetings - Doc Type: Memo

ATTACHMENT

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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 18.4' 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 supply (Mainstem) 20.51 11.1-16.4
Upper Basin Uses 2.55 3.7'
Upper Basin Reservoir Evaporation _n 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

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For the period 1903-1922. This was the amount reported by Delph E. Carpenter in his Historical
Memorandwn 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 Representatives. In his Comments to Congress on the Colorado
River Compact, Commissioner of Reclamation Arthur Powell Davis estimated the reconstructed flow at 18.1
maf/yr. Con~. 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,
September 30,1996. For the twelve-year period 1953-1964, the average annual virgin flow at Lee's Ferry was only
11.6 maf.
3 Tree ring analysis. The lowest ten-year reconstructed record was for the period 1584-1593.
4 As used by the Lower Colorado Region, Bureau of Reclamation, informal communication.
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, Con~. 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 8.0 maffor 1997. However, 19997 is a year of declared surplus. Under a normal
year, Lower Basin mainstem uses are limited to 7.6 maflyr.
9 The Bureau of Reclamation Conswnptive Uses and Losses Report, 1981-1985, shows total Lower Basin
reservoir evaporation of about 1.0 maflyr. However, current accounting of the Lower Colorado Region of the
Bureau of Rec1amation estimates 1.8 maf/yr., informal communication.

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