WSP02832

• File Number: 8410.200.60
• Description: Basin Multi-State Organizations - Missouri River Basin Commission - Reports
• Date: 4/15/1974
• Author: TAC
• Title: Water Supply Information Requested by States' Technical Group
• Water Supply Pro - Doc Type: Data

. .

The monthly distribution of depletions varies somewhat from year-to-year
and from State-to-State because of variations in precipitation, tel~peratures,
length of growing season, availability of storage supplies and other factors.
However, the monthly distribution of irrigation is approximately the same
whether the irrigation ';as 'federally fWlded, State funded, or privately
financed. The approximate monthly percentages which are applicable on
an average uasis to determine monthly depletions by functions or categories
are -listed in the attached table. (Table 1).

In our ear-lier presentation, which compared by a series of tables the
1949-level monthly flO\;s at each main stem reservoir against the existing
1949-}970 monthly depletions and the estir.1ated depletions for 1949-2020, the
monthly distribution of depletions was derived by an approximate procedure.
In this earlier study, the lumped annual depletions for irrigation, I;atershed
treatment, and tributary reservoir evaporation ';ere distributed by months
in accordance with the expected monthly distribution of irrigation depletions.
Application of the Table 1 percentage distributions to the respective annual
depletions for each function or category, gives Slightly different results,
as demonstrated in the attached Table 2. Similar computations can be made
for other reaches or locations if approximate, but reasonable, monthly
depletion distributions are needed by the State Technical Committee.
Regardless of the exact computation procedure used, it continues to be our
opinion that an assured supply of water from the 1.lissouri River above Sioux
City to serve future needs will require storage regulation by reservoirs.

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E. \\. HcClendon
Chainnan

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Phil Q. Gibbs
Hemb!lr

2 Inclosures
1. Table I - t.lonth1y Distribution of Annual Depletions in !..
2. Table 2 - l10nthly Distribution of 1949-1970 Depletions for the ~Iissouri
Basin above the Garrison Dam.

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