WSP01461

• File Number: 8549.800
• Description: Rio Grande Basin-Miscellaneous Small Projects and Project Studies-Rio Grande Assessment
• State: CO
• Basin: Rio Grande
• Water Division: 3
• Date: 2/1/1981
• Author: Brandes Kier Stecher
• Title: Water Resources Reference Base for the Assessment of the Rio Grande Region
• Water Supply Pro - Doc Type: Report/Study

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Grande Project is the responsibility of the Water and Power Resources Service
(WPRS), however the distribution of stored water for irrigation and other uses
is determined by local districts under provisions of recent agreements be-
tween the districts and the United States. Annual releases from Elephant
Butte and Caballo Reservoirs are subject to Compact provisions and the stipu-
lations of the United States-Mexico Treaty of 1906.

The third major mainstem impoundment in New Mexico is Cochiti Reservoir
located about 200 miles upstream of Elephant Butte. This project was con-
structed by the Corps of Engineers primarily for flood control and sedimen-
tation purposes, however 50,000 acre-feet of permanent pool storage are
allocated for recreation.

As a result of a treaty between the United States and Mexico in 1944,
the surface waters of the Rio Grande below Fort Quitman, Texas, were allo-
cated between the two countries and three major storage reservoirs were
authorized for construction in this reach to provide for water supply, flood
control, and generation of hydroelectric power. Two of these reservoirs have
been built, Amistad and Falcon, and together they provide a total of over
eight million acre-feet of conservation and flood control storage capacity.
Releases from the reservoirs are used primarily for irrigation of farmland in
both the United States and Mexico portions of the lower Rio Grande valley.

At the end of 1980, the ten major reservoirs in the Re9ion with conser-
vation storage allocations, as indicated in Table 3, contained a total of
approximately 7,200,000 acre-feet [4,9] of water, or about 75% of their com-
bined conservation storage capacity. Almost three-fourths of this quantity
was stored in Amistad and Falcon Reservoirs in Texas.

Surface evaporation from reservoirs in the Region varies appreciably.
About 70 to 80 inches per year are lost to evaporation along the Rio Grande
mainstem from Falcon Reservoir upstream to Elephante Butte and in the Pecos
River basin from its mouth at Amistad Reservoir upstream to Lake Sumner.
Reservoirs located at higher elevations on tributaries of the Rio Grande
{Heron, El Vado and Abiquiu} and in the headwaters of the River in Colorado
{Rio Grande, Platoro and Sanchez} typically lose 40 to 50 inches per year to

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