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. -2- During the 13th and 14th months, July and August 1973, the United States discharged to the river channel below Morelos Dam 7,400 acre-feet of Wellton- Mohawk drainage and substituted therefor an equal volume of waters of better quality. However, the resulting mean salinity for the two month period was 25 parts per million higher than that for the same period in 1972, due to an increase in Well ton-Mohawk drainage waters incident to infiltration attending 1973 flood releases from Painted Rock Reservoir described hereinafter. Exhibit 2 shows a graphical comparison of daily salinities at the Northerly International Boundary resulting from United States operations under Minute No. 241 during the l4-month period ending August 31, 1973, with those resulting from United States operations during the previous year. MEXICAN OPERATIONS . Mexico elected to further reduce the salinity of river waters diverted at Morelos Dam, and for this purpose discharged to the river channel below Morelos Dam during the l2-month period July 1972 through June 1973, all of the remaining 95,550 acre-feet of Wellton-Mohawk drainage, with the under- standing that this remaining volume would not be replaced by substitutuion waters. The combination of United States operations under Minute No. 241, plus the Mexican operations during the l2-month period, resulted in the mean salinity of waters actually diverted by Mexico at Morelos Dam being lowered to an average of about 980 parts per million, approximately 130 parts per million higher than the mean salinity of waters arriving at Imperial Daml) during the same period. During the 13th and 14th months of United States and Mexican operations, July and August 1973, with all drainage waters of the Well ton-Mohawk District discharged to the Colorado River below Morelos Dam, amounting to 34,570 acre-feet, the resulting mean salinity for the tWD_mo.n.th8-.Was.ihe-Same...as-foL-t.he-same-two_monUl-p e r i ad i I>-l,9.].2.,-a1>0" t 970 parts per million. Exhibit 3 shows a graphical comparison of daily salinities at the Northerly International Boundary resulting from the combination of United States and Mexican operations under Minute No. 241 with those resulting from the combination of United States and Mexican operations during the previous year. RELATED MATTERS Flood flows resulting from abnormally high runoff from the upper Gila Basin in the first part of 1973 entered Painted Rock Reservoir and flood releases 1) Based on chemical analyses. .