WSP12121

• File Number: 8278.200
• Description: Title I - Welton - Mowhawk
• Basin: Colorado Mainstem
• Date: 9/1/1972
• Author: C.C. Taybor
• Title: Wellton-Mohawk Drainage and the Mexican Salt Problem
• Water Supply Pro - Doc Type: Publication

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delivers water to North Gila, South Gila, Yuma Mesa, Yuma Auxiliary and Well ton-

Mohawk. In the background you will see Senator Wash Dam which was constructed

in 1964 and about which we will hear more later.

Figure 5 is a picture of Morelos Dam completed in 1950 by Mexico. 'This

diverts water into the Mexicali Valley and, through a siphon under the river at

San Luis completed in June, 1963, delivers water to the San Luis Valley in Sonora.

Prior to June 1963 all diversions into ,San Luis Valley were pumped.
Well ton-Mohawk
And now back to Figure 1 and the Well ton-Mohawk. The irrigation facil-
ities for this project were completed in 1952. At that time it was considered
that a drainage system was not necessary. Old wells which had been used for

irrigation during the 40's could be used for drainage by allowing this water to

run into the Gila River and drainage would be adequate. However, this was found

not to be true, probably due to a geological barrier in the Dome area which did
not allow adequate underground return of water to the Colorado River.

Well ton-Mohawk has been accused of mining groundwater, collected in

the underground throughout the pumped irrigation period from 1912 to 1952 and

grown more saline due to this recycling process, that never came from the Colorado

River. This may be true although I believe the Gila to be part of the Colorado
River basin. However, this District is operating its irrigation and drainage in
accordance with practices accepted as the b~st by any authority on the subject.
Figure 6 is a highly distorted cross-section of the Well ton-Mohawk
mesa and valley which shows the gravel aquifer which underlies the Gila River.
This serves as an underground reservoir which collects percolated irrigation

water and allows it to be pumped thereby keeping the groundwater below the

root zone of the crops. This is one ,of the few irrigation districts in the

world that can effectively and economically drain itself by pumping. Then a

concrete-lined channel was constructed into which the existing drainage pumps,

formally irrigation pumps, and additional new drainage pumps could discharge

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