WSP06206

• File Number: 8278.200
• Description: Title I - Wellton-Mohawk
• Basin: Colorado Mainstem
• Date: 8/1/1988
• Author: USDOI/SCS
• Title: Wellton-Mohawk ON-Farm Irrigation Improvement Program Post-Evaluation Report
• Water Supply Pro - Doc Type: Publication

In August 1973, Minute 242 was signed by the Commission. In order to
i~plement this agreement, Public Law 93-320, "Colorado River Basio Salioity
Cootrol Act", was passed by the Congress of the United States and signed into
la. in June 1974. The law authorized the construction and operation for .orks
in the Colorado River Basin to control the salinity of water delivered to
Mexico, including any measures deemed necessary to improve irrigation water
management. The Bureau of Reclamation was designated as the administrative
agency.

Title I of the act peraits i.plementatioo of the provisions of Hioute 242.
The United States shall deliver 1.36 million acre-feet of water annually to
Mexico. The average salinity shall be no more than 11Sppm (~30ppm) over
waters diverted at Imperial Dam.

The major feature is desalinization by treating the return flows from the
Wellton-~ohawk District. The desalinization plant is under construction.

Included in the Desalting Complex Unit are structural measures consisting
of: (1) a membrane-process desalting plant, a pretreatment plant, and the
necessary works to treat drainage water from the Wellton-~ohawk Division, Gila
project: (2) extension of the concrete-lined bypass drain from Morelos Dam to
the Santa Clara Slough in Mexico. The bypass drain keeps Wellton-~ohawk
saline drain flows from mixing in the Colorado River water.

To reduce the cost of desalinization, other programs were planned which would
reduce the volume of the return flows. Nonstructural measures consist of:
(1) an irrigation efficiency iaprovement program in the Vellton-Mohawk
Divisioo; and (2) an irrigable acreage reduction program in the Wellton-~ohawk
Division.

These nonstructural measures provided for a multi-agency approach of on-farm
water management and improvement assistance offered to farmers in the Wellton-
~ohawk District. Agencies involved and their programs included:

Bureau of Reclamation
--- Irrigation Management Service (IMS) program
--- acreage reduction
Agricultural Research Service
--- research and demonstration
Cooperative Extension Service
--- education and information
Soil Conservation Service
--- on-farm irrigation improvement program

This report is an evaluation of the on-farm irrigation i.provement program in
the Vellton-Kohavk Division. The Bureau of Reclamation agreed to transfer
money to SCS for technical assistance and cost-sharing money to water users
for the installation of on-farm system improvements. This permitted SCS to
implement an expanded voluntary on-farm irrigation water management program to
reduce drainage flows.

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