WSP11716

• File Number: 8507
• Description: Rio Grande Project
• State: CO
• Basin: Rio Grande
• Date: 7/1/1997
• Title: Water Management Study: Upper Rio Grande Basin part 1
• Water Supply Pro - Doc Type: Report/Study

Water Management Study: Upper Rio Grande Basin

The Rio Grande Compact. Texans joined their Mexican neighbors in
complaining about the water shortages that materialized at the end of the
nineteenth century. Following much disagreement and negotiation, in 1938
Colorado, New Mexico, and Texas entered into the Rio Grande Compact. The
Compact was intended to safeguard and perpetuate the allocation of the Rio
Grande's surface water among the states, as it existed in 1929. By this time,
development in the Colorado portion of the Basin was consuming about
600,000 af of water annually, about two-thirds ofthe average annual flow
that otherwise would pass into New Mexico (Daves 1994).

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The Compact stipulates the amount offlows allocated to each participant of
the agreement. State laws are oflittle significance relative to the Compact,
in matters of interstate water allocation. Each state's share is a stipulated
percentage of actual flows, and thus, fluctuates based on the amount of
annual runoff. Colorado must deliver about 20 percent of the gauged flows to
New Mexico during dry years, about one-third in an average year, and more
than 50 percent in a wet year. New Mexico, similarly must deliver 57 per-
cent of the gauged flows to Elephant Butte Reservoir in dry years and up to
almost 90 percent in extremely wet years. (New Mexico's performance
relative to its obligations is measured at Elephant Butte, which lies about
100 miles upriver from the Texas border.) Table 1.1 shows the apportion-
ment among the states for a typical year, as estimated by Daves (1994).

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Table 1.1.-Apportionment of water among the states under the Rio Grande
Compact during a typical year'

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Delivery Available for
Total flow requirement depletion'
Colorado 975,000 308,480 666,100
New Mexico' 1,194,000 887,000 307,000
Texas' 887,000 NA 707,000

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Source: Daves (1994).
I All numbers in acre-feet (af).
2 After evaporation.
'The Middle Rio Grande Valley, from eochiti to Elephant Bulle Reservoir.
'Includes New Mexico, below Elephant 8ulle Dam, and Mexico.

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