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CONFIDENTIAL -3- This estimate was on the basis of essentially all tile and no by-passing. On the basis of 4000 p.p.m. it would result in an average annual salinity to Mexico of 1330 p.p.m. and maximums of 1510 to 1750 p.p.m. in three months. c) In the current reconsideration of a by-pass, Interior is understood to predict that the Wellton-Mohawk effluent would be approximately 500 p.p.m. This estimate is based upon by-passing 90 days, and would result in an average salinity to Mexico of 1410 p.p.m., with maximum of 1520 to 1720 p.p.m. in four months. Analyzing the estimates, there is the apparent inconsistency that by-passing for 92 days results in higher salinities of effluent to Mexico than by-passing for only 50 days, or with no by-passing. The opposite should be true. We must continue to be forthright with Mexico, and advise what they can expect in the immediate future, with no commitment. We should not make a proposal to Mexico which appears so inconsistent as indicated above. Attention is again drawn to the need to recognize that a by-pass solution is applicable only as long as and to the extent excess waters obtain which can be by-passed without loss to the United States. This could be 10 years or more, but might be 5 years or less. Recommendation It is recommended that Interior be requested to review its proposed "by-pass" operation for 1.5 salt balance with a view to determining the minimum peak salinities which it can achieve in the immediate future with selective pumping and reduction of pumping. It is recommended that Mexico be advised of the estimated salinity of Wellton-Mohawk effluent which it may expect in the immediate future, but without commitment. For this purpose it is recommended that Interior be requested to furnish a statement of the probable average and maximum quantity and quality of Wellton-Mohawk effluent for each month in the immediate future. J. F. Friedkin Commissioner CONFIDENTIALEpson Perfection 4870 Photo, 400 dpi, 24 bit, 10,336,768 byte