WSP04615

• File Number: 8278.400
• Description: Title I - Mexican Treaty
• Basin: Colorado Mainstem
• Date: 2/1/1963
• Author: USDOI/BOR
• Title: Special Studies - Delivery of Water to Mexico
• Water Supply Pro - Doc Type: Publication

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2. HistoricaJ. Flows Prior to Hoover DIllII Construction. Part A

of Table No.3 shows mont~ and yearly runoff of the Colorado

River near Grand CaDyOn for water years 1923 through 1962. During

this period, the annuaJ. flows ran~d from a low of 4,565,000 acre-

feet in 1934 to a high of 19,430,000 acre-feet in 1929. Inspection

of the table shows, aJ.so, that there are wide variations in monthly

flows through the period. Part B of Table No. 3 shows the momen-

tary max:llIIl.un dischar~ during water years 1923-1961 at this station

and the minilm.un day during each of the years. It is readily

obvious that development along the lower river prior to re~ation

of flows by Lake Mead and the other lower basin reservoirs was

necessarily limited by the e;vailable low flow during the late

SUllllller months and by the JlI8.gni tude of the flooclflOl/B which usually

occur during May or June s.s a result of snowmelt runoff.

3. Operation of River - Average Annual. Supply and Requirements.

The water supply of the Colorado River available to users of main-

stream water below Hoover Dam hs.s been ana4rzed on the basis of

records of releases from Lake Mead during the 22-year period,

water years 1941 through 1962. This period covers a decade of above-

average water supply and a decade of below-average water supply, and

probably more nearly reflects the current level of upstream deple-

tions than wouJ.d a lon~r period of record. The avera~ annual.

release from Hoover Dam during this period hs.s been about 11.4

million acre-feet. Releases during the 10-year period, waterJ

years 1941 through 1950, averaged about 13.0 million acre-feet,

while during the past 12 years through water year 1962, the e;verage

annual. release has been only 10.1 million acre-feet. A monthly

.

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