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Show THE ALL-AMERICAN CANAL. 45 Pilot Knob is surrounded by this mesa formation on three sides- to the north, to the west, and to the south. On its remaining easterly side, its base has at times been washed by the waters of the Colorado River, and a spur of the mountain has been cut away to provide suitable foundation for the Hanlon gate with which, since 1906, the flow of water into the Imperial Canal has been controlled. Southward from Pilot Knob the mesa formation is much broken up by washes which have been cut deep and wide to an outfall upon the lower delta land of the river. The mesa elevation around the base of Pilot Knob is generally at or above 200 feet in elevation. The bottoms of the sand washes on the proposed canal line are generally at about 130 to 140 feet in elevation. Between them the remnants of the mesa, in long narrow ridges, with tops more or less broken, extend off toward the south into Mexico. The boundary line is just far enough south of Pilot Knob to leave space for a canal which, at the elevation attainable under use of Laguna Dam as the point of diversion, will cut through these mesa ridges and cross the intervening washes, with water grade practically at or slightly below the surface of the sand in the larger washes. At a point a little less than 2 miles from Hanlon's the canal will be out of this broken ground and the deep cut into the mesa will be continuous and uniform for about a mile and a quarter to the easterly edge of the sand hills. Entering the sand area the course of the canal for another mile and a quarter will continue parallel with the boundary, being here located across an area over which low dunes are drifting. These dunes are irregularly distributed. Any course through them is as good as any other course. There was, therefore, no object in departing from a direct course westerly. But a continuation of this course would send the canal through a broad area of high sand ridges. It was found that by deflecting the course of the canal toward the northwest it could be kept for a mile in a iocation on which the surface of the sand was but little above the surface of the mesa and that one of the main sand ridges could then be pierced in a cut only a little over one-half mile in length westerly to a long narrow bare stretch of mesa surface which has been designated on the maps as Government Gap. The adopted canal location will follow this gap for 1£ miles to its westerly extremity. For three-fourths of a mile thence, still on a westerly course, the canal will cut through a mass of sand with a number of summits at elevations approximately 50 feet above the surface of the mesa. It is on this stretch of canal that the drifting sand is most likely to prove troublesome. Upon leaving this three-quarter mile stretch the canal will be cut for about one-half mile through the westernmost ridge of sand, which crests on the canal line about 80 feet above the surface of the mesa and about 105 feet above the water surface of the canal. |
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Original book: [State of Arizona, complainant v. State of California, Palo Verde Irrigation District, Coachella Valley County Water District, Metropolitan Water District of Southern California, City of Los Angeles, California, City of San Diego, California, and County of San Diego, California, defendants, United States of America, State of Nevada, State of New Mexico, State of Utah, interveners] : California exhibits. |