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<br />The two Sections of the Commission have reaqhed agreement in principle in <br />this matter and details are being worked out. <br /> <br /> <br />Protective Levees Above:Morelos Dam <br /> <br />Article 12 of the Treaty provides for construction at Mexico's <br />expense, of such levees as in the opinion of the Commission shall be <br />necessary to protect land within the United,States, principally in Yuma <br />Valley, from floods that might result from the construction, operation <br />and maintenance of Morelos Dam. Constructibn under this provision comprises <br />largely the raiSing of existing levees. In:addition, certain other work is <br />required as a domestic undertaking, to brin~ the levees up to the grades and <br />sections required without the Mexican diversion structure. Construction was <br />delayed pending action by Congress on the Corps of Engineers' recommendation <br />for a flood control dam on Gila River at Painted Rock, since if that dam <br />were built, the required height of the levees would be , to 7 feet less <br />than otherwise. In May 1950, Congress auth~rizedconstruction of this dam. <br />The Bureau of Reclamation then proceeded in, accordance with understandings <br />with the United States Section of the CommiSsion to let contracts for re- <br />construction and raising of the levees, both the Mexican portion and the <br />United States portion, as a joint project, to guard against a design flood <br />of 140,000 c.f. s. at Yuma. Work began in July and probably the greater <br />part will be completed in the coming year. <br /> <br />Flood Control - Lower Colorado River <br /> <br />Article 13 of the Treaty relates to flood control on the River <br />between Imperial Dam and the Gulf of California. The problem is to guard <br />against flooding of delta lands including the now highly developed lands <br />of Mexicali Valley and those of Imperial Valley. Even with the authorized <br />dam on Gila River, complete flood control ~ill not be effected. Studies <br />by the Bureau of Reclamation indicate thatirunoff from the watershed below <br />existing and authorized dams on the Colora~o and Gila Rivers may result in <br />flood peaks up to 140,000 c.f.s. Since th~ river channel is expected to <br />deteriorate, a serious flood problem appeats to be in the making in the <br />delta. . <br /> <br />Incident to regulation and depletion of river flows, natural <br />vegetation has made significant encroachments on the river channel in the <br />delta. River surveys by the Commission indicate that the riverbed has <br />risen since 1947: nearly two feet between'Laguna-Dam and Yuma; about one <br />foot between Yuma and Morelos Dam; and abop.t two feet between Morelos Dam <br />and the southerly international boundary. ! In Mexico the bed has risen ' <br />during the past two years about one foot ip. the first 30 miles, and two <br />feet near the head of tide water where thei river is building its deltaic. <br />cone. <br /> <br />The rise in river bed below Lagu~ Dam may be attributed in large <br />part to operation since 1945 of the desilting works at Imperial Dam, result- <br />ing in overburdening the depleted flows with silt and depositing it in the <br />channel. Problems of channel aggradation :in the delta will be further <br /> <br />-30- <br />