WSP12542

• File Number: 8282.400
• Description: Colorado River Operations and Accounting - Deliveries to Mexico
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 5/1/2001
• Author: David and Lucille Packard Foundation
• Title: Immediate Options for Augmenting Water Flows to the Colorado River Delta in Mexico - RE-Colorado River-Mexican Delta Issues - 05-01-01
• Water Supply Pro - Doc Type: Report/Study

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IV. MANAGEMENT OF COLORADO RIVER WATER IN MEXICO

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Irrigation in the Mexicali Valley began in the 1880s, through the use of canals constructed by
the California Development Company. Those canals provided water to both the Mexicali and
Imperial Valleys, with the Canal lndependencia (previously named the Alamo Canal) serving both
valleys. When the Canal Independencia headworks at the Colorado River west of Yuma failed in
1905, floodwaters destroyed thousands of acres of Mexicali Valley farmland. After the headworks
were repaired in 1907, the core irrigation system that exists today in the northern Mexicali Valley
was constructed and began operation. Because the Canal Independencia served fannland in both
Mexico and the United States, many disputes arose over the methods of operating, maintaining and
funding related activities. The unreliable flow of the Colorado River and its huge sediment loads
caused serious operational difficulties. .

By the late 1930s, about 50,000 hectares (125,000 acres) were being farmed in Mexicali and
San Luis Rio Colorado Valleys using about 750,000 acre-feet of water per year. Much of this water,
particularly during low flow periods, was brackish agricultural return flow from the farms in the US.
With the completion of Hoover Dam in 1935 the Colorado River flow stabilized, and the All
American Canal was constructed just north of the Mexican border so that it was no longer necessary
to convey water ,to the Imperial Valley through Mexico.

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Seeing increasing water use in the United States, Mexico sought to secure its rights to
Colorado River water. The ratification of the 1944 Mexican Water Treaty by both nations secured
for Mexico the right to about twice the water it was then using, 1.5 million acre-feet per year.
Following ratification of the Treaty, Mexican land cultivation and water use steadily increased By
the 1960s and continuing to the present time, about 186,000 hectares (460,000 acres) of land in the
Mexicali and San Luis Rio Colorado Valleys are fanned using about 1.42 ,million acre-feet of water
per year. Today, water is delivered at two points, the Northerly International Boundary, immediately
upstream from Morelos Dam (about 1,360,000 acre-feet per year) and at the Southerly International
Boundary near San Luis, Arizona, and San Luis Rio Colorado, Sonora (about 140,000 acre-feet per
year).

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To supplement the Colorado River water delivered under the Treaty, wells have been
installed and now produce about 730,000 acre-feet annually. Figure 3 shows the canals and drains of
the Mexicali and San Luis Rio Colorado Valleys.

A. Interaction between CNA and the Modules

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Mexico's National Water Law provides for institutional and strategic management for all
waters that belong to the nation. Under this law, the Comision Nacional de Aguas (CNA) is the
federal agency that defines water policies and administers the implementation of those policies. A
branch office of CNA is located in each state, including Baja California. Most day-ta-day
management and administration activities are delegated to the state office.

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