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CONFIDENTIAL -2- as you know, the President, in his discussions with the President of Mexico on June 29 and 30, assured the Mexican President that he would do his best to assure permanent and effective solution prior to October 1, 1963, so that there would not be a ?? of the high salinity experienced in the winter of 1961-62. The March communique of the two Presidents stated that the objective of the two Governments is to agree upon and actually put into operation remedial measured within the shortest possible period of time and without prejudice to the legal rights of either country. Nevertheless, in considering the Panel reports, I believe we must face realistically the strengths and weaknesses of the United States legal case. Such examination is especially apropriate since, in default of a settlement, the Mexicans could bring the matter before a federal court or before the International Court of Justice, and there is reason to believe they are preparing to do so. This Department continues to be of the view that the United States has no Treaty obligation to Mexico to deliver water of any particular quality. Is his discussions with President Lapes Mata??os in June, the President carefully refrained from conceding any obligation as to quality and in our discussions with Mexican officials we have exercised similar caution. While the Mexican Commissioner has acknowledged that Mexico must accept return flows from United States irrigation as part of her Treaty deliveries-and, as a practical consequence, this would mean a deterioration in the quality of the water deliveries as irrigation on the United States side of the boundary is systematically increased over the years-the Mexican Commissioner contends that the Treaty requires Mexico to accept only return flows resulting from "normal" irrigation practices and that the effluent from the deep-well pumping at Wellton-Mohawk does not fall within the scops of "return flows" as used in the Treaty. It might be difficult successfully to rebut this contention. Even if a court were to uphold a United States contention that the effluent from Wellton-Mohawk is "return flow" as defined by the Trusty, this does not necessarily mean that a court would not examine into the reasonableness of the United States practices affecting quality in light of the general principles of law governing international rivers and the use of such rivers by upper riparians when such use causes serious injury to the lower riparians. In the arbitral sword made on November 16, 1957, in the dispute CONFIDENTIALEpson Perfection 4870 Photo, 400 dpi, 24 bit, 1,740,176 byte