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. . . Second, the Wellton-Mohawk Division of the Gila Project, a 75,000- acre irrigation project utilizing Colorado River water and located along the lower Gila River just east of Yuma, Arizona, began ground-water i\.') l\J pumping operations in 1961 to drain off excess ground water which G W was approaching the crop root zone in many areas. The Project had reached this condition by the application of excess irrigation water, without drainage facilities, for nearly 10 years, initially to leach some of the more saline soils, and annually thereafter to maintain salt balance. This pumped drainage water, at first in excess of 200,000 acre-feet per year at 6,000 parts per million (p/m), was diverted to the Gila River channel where, consequently, it flowed into the Colorado River at their confluence, just east of Yuma. The combination of saline Wellton-Mohawk drainage and lower runoff in the basin (less water for dilution) increased the salinity of Colorado River water delivered to Mexico at the Northerly International Boundary from an annual average of about 800 p/m to nearly 1,500 p/m by 1962. As a consequence of continued protests by Mexico, the United States began to bypass some, then eventually, all the Wellton- Mohawk drainage to the old river channel below Morelos Dam, which necessitated its replacement by other waters from above Imperial Dam in the United States, since the drainage water had been accredited as part of Mexico's annual 1.5 million acre-feet allotment since it had first been pumped from Division lands. During the 60's and early 70's, representatives of both Govern- ments had worked on various resolutions to the salinity problem which, 2