AZ vs. CA:04 California Exhibits, Vol. IV; Nos. 151-192

page 34

34 THE ATI,-AMERICAN CANAL. TEDE CANAL CAPACITY. In determining that the all-American canal should be planned for a capacity of 9,000 second-feet, consideration was given to the following facts: On the 586,000 acres within Imperial Irrigation District it is estimated by those supposed to be best informed that 515,000 acres will ultimately be under cultivation and therefore irrigated. The west-side canal can be extended and constructed on lighter grade whereby some 40,000 acres more west-side land, not now within the district, can be added to the irrigated area. On the eastrside mesa there are about 200,000 acres of land of which it is estimated it is feasible to irrigate 140,000 by gravity flow. Northward from what is generally known as the east-side mesa on the eastern slope of the valley and extending to Coachella Valley there are about 115-000 acres of land that will be commanded by an extension of the mesa canal, of which probably 75,000 acres net should be considered as being suitable for irrigation. Still further north lies the Coachella Valley where irrigation might be extended to possibly more than an additional 75,000 acres. Of pumpage area there are about 30,000 acres on the east-side and about 25,000 acres on the west-side mesa. Without at the present time including lands so remote as those to the westward of the northerly end of Salton Sea, the net irrigable areas to be considered aggregate 900,000 acres. It is to be understood, however, that whenever it shall become apparent that water is available for a larger area and the demand for extension is made, the canal can be enlarged by dredging and the irrigated area can be extended beyond the limit named as the basis for the project. Based on the experience in the Imperial Valley and in the Yuma project it has been found that a delivery of about 3.33 acre-feet of water per acre per year and a diversion from the river of about 4.44 acre-feet for each acre of the irrigated area should adequately meet the requirements of general farming as the same has been practiced in these regions. It is known that the losses of water from the Imperial Canal in its course through Mexico in a distance of about 50 miles are from 15 to 20 per cent of the amount diverted from the river, or in round numbers, according to the canal stage, about 7.5 to 20 second-feet per mile of canal. It is also known that the losses in the secondary mains in Imperial Valley are light, probably not much in excess of 10 per cent. The all-American canal will be subject to ordinary canal losses from the Laguna Dam until it gets beyond Pilot Knob. Thence westerly for nearly 20 miles the water surface of the canal will be deep in the ground. The canal bottom in this stretch will be at an average depth of about 50 feet below the surface of the mesa. The -canal may for a time, at the beginning of operation, lose water here as it would if in shallow excavation, but presently the lower layers of the mesa formation will be filled with water and the canal