WSP06898

• File Number: 8507
• Description: Rio Grande and Tributaries NM
• State: NM
• Basin: Rio Grande
• Date: 4/5/1948
• Author: Secretary of t Army
• Title: Letter from Chief of Engineers Submitting a Report on a Preliminary Examination and Survey of Rio Grande and Tributaries, NM, Authorized by Flood Control Act Approved Aug 18, 1941
• Water Supply Pro - Doc Type: Report/Study

XXVllI

LETTEil OF TRANSMITIAL

necessary during the study period, indicate that fl material increase
in consumption of tributary milow reachmg the rIver below OtoWI
gaging station would be neccsslt;y to supply the irrigation require-
ments of the middle valJey, Such mcreased consumptlOn would
cOL'st.it.ute. fin additional debit to New 1\1exico because such consump-
tion would be caused by works constructed after 1937,
4, New Mexico was not charged as a debit with the nonrecoverable
bank storag" which would result from the operation of the reservoir:;
proposed in the reports of the agencies,
The Corps of Engineers stal.e that operation 3-RR of the propose' I
project. is merely for illustrative purposes and that otber types of
operation could be Dlllde, They suggcst one type which would rcsult
in substantial curry-over in the reservoirs subject to eva.cuation based
on the results of snow surveys.
On page 69, pllragmphs 165 aDd IGG of tlIe appendix C, Hydrolog,,'
of the Corps of Engineers' Report, the following statement is made:
165. OTHER OPERATION STUDIEB.-!\ljmerous other opera.tion studies have
be€ll made during t.he preparat.ion of thi::; suryey report.. AUholl{lh the basic cri-
teria, including the depletion in New Afi'-xico, hat'c been varied in many of the stl/dies,
it is important to note that so long a8 the terms oj the Rio Grande compacl are followed,
the dill/sinn of 1L:ater between Colorado, New JUexico, and Texas will- remain prac-
tically the 8ame for et'cry operation. For t.he IS-year period used in most of the
studies (HJ25 to 1942) it has becn fOllnd that Colorado wiH alwllYs get about
13,340,000 acre-feet of water, New Mexico will be 9,780,000 acre-feet, and the
Elephant Butte project will get 14,010,000 acre-feet. A cha1lge 1"11 the criteria
affccts only the division of water in New J.hxico betwcen bene-fidal and l10llbencficial
uses. 11 is impor/ant to poil/t oul that the method (If o}Jerafi(ln shown as Operatwn
Study No. 3-UR ~.8 not a recommended method of operation but only one possible
method. There are nUlnerous other methods by which the project may be oper-
ated and it is considered. that. 0. final method of operation must he determined after
the project is :l.ctun.lly in operatioll" Any final method of operation should be
agreed to by all intere!ited part.ie~. [Italics furnished.J
ltil:i. EVACUATION SCHEDUL8.-Although Operation SLudy No. 3-RR ShOWll
in this report does not make any attempt to show that wat.er may he retained in
the flood-control dams, ot.her stuoie!'. indicate that the retention of water upstream
in accordance wit,h predet.ermined evacuation sc:hedules is possible. Because
sprinl1: fllll-off may be predicted from snow surveys it is possible to maintain water
in Chifto and Chamita Dams in accordance with this predetermined Elcherlule. A
tentative schedule used in some of the wat.er studies pro\'ides that these reservoirs
be evacllo.ted to {.he following quantity in st.orage by December 31 of each year:
.-tat-fal
700,000
500, 000

ChiAQ Reservoir_ _ ____~_ _____ _ ___. _ _ __ ____ _ _ _ _ __ __ _~ _ __ _ ___. _ __
Chamita Reservoir ______ __ _ ____ _ _ _ __ _ ___ __ _ ~ ~ _ _ _ __ __ _ __ _ __ ___ __

TotaL _ __ _ __ __ _ _ . _ _ _ __ _ _ __ _. _ _ . _ _ __ _ _ _ __ __ _ _ _ _ __ . . _ _ __ _ 1, 200, 000

Evacuations after December 31 would be based on the predicted fUn-otTo In
the e\.cnt of an exceptionally he3.v)' snowfall, and if the forecasts should indica.te
a larger than normal spring run-off, the 1,200,000 acre-feet of storage or any part
thereof could then be ent.irely evacuated by April 1:5, without exceeding thc safe
capacity of the challllcl through the developed areas. If the ::;now melt forecasts
indicated that the spring flood WOllIn be comparatively small in \'olume, then the
amot\nt of wat.er rele.'lsen from t.he resen.oirs aft.er .Tn,llU:l.n' 1 could be reduced
B.ccorrlirlg-Iy. By o).:xmlting Ole dam." ill this mlllJllCr t.here ",'ill be a .sa....ing in
water hecau~e uf the lower rate of evaporution at higher alt.itudes, there would be
increased benefits to fish and wildlife and to recreaLional developments, and tbe
retent.ion of water upstream until needcd might provide the basis for producing
power because t.he releases could be more uniform .9.LJd dependable o\'~r lunger
periods of time.

The firs~ two sentences which are ill italics in t.he qunt.fi.t,ion of

paragraph 16.5 of l.he appendix C of the report of the Corps of En-

gineers indicate plainly a lack of lInderstandiug of the operation of the

Rio GnuHlc COTIlpa.ctJ \vhich permits the passing to all up~trenm reser-