Arizona republican., 1904-05-24

extending fifty feet down stream. The great length of this dam provides such an ample spillway that the depth of water going over it at normal stages VIII De comparatively slight and the current above it greatly reduced in ve- i'city. Both ends of the dam will be III soad rock. At each end of the dam there will be gates opening into large setllng basins, either in the natural iock or in solid masonry. These basins VIII be about 5000 feet long and of much greater width than the canals they feed.
 Ihe rlver carries a very large per- centage of silt, of which, for various reasons, It is desirable to get rid of as much as possible, The fall of the rlver itself is about one foot to the mile The interpretation of the dam will therefore, result in establishing prac- tieaIly a pool above it and thus check the current. which otherwise is rapid me checking of the current causes the deposit Of the silt. The water. taken lirst into the settling basins, will pass over flash boards, the elevation of "hlch can be regulated. so that the pro- cess results in a "skimming" of the water; that part of it only at, or with Tn foot of the surface of the water ir the pool being admitted. The settling basins will be about 5000 feet in length and eXcavated in the solid rock. or if Tn earth, that part in earth will be paved. The bottom of the basins will have fall of eleven feet from the dam to the gates to be provided for discharge into the river below the dam, The width and depth of the basins greatly exceed the width and depth of the canals. The velocity of the water passing from the basins to the canals is greatly retarded and as conse- quence the greater part of the silt re- maining in it after having been "skim- med" by the flash boards. is deposited In the settling basins. At intervals of time to be determined, I suppose, by practice, the basins can be readily and effectively sluiced and cleaned of the silt deposited in them.
 The canal on the California side is designed to supply about 16,00O acres of land belonging to the Indians A plan for the allotment of the land to the Indians has been provided. This canal will have a capacity of about 200 cubic feet of water per second, or ex- piCSStu III UllHeT S lnCneS, as We are ac- customed to that unit of volume. about 5000 inches. The canal on the Arizona side, designed to supply the settlers about Yuma. will have a capacity of about 12O0 cubic feet, or about AS, 600 inches and will supply water for be- tween 10000 and 75O00 acres of land available for cultivation
 ''The conditions prevalent under this nrOnnCpd SNC ba culiar, necessitating the adoption of severa, features diametrically opposed to each other. In the first place, water must be diverted from the river and conveyed to the lands for their culti- vation. For this purpose the diversion dam and the irrigating canals which ' 'have mentioned are to be constructed. The regime of the river is such that during a part of each year a consid- erable portion of the lands to be re- claimed are flooded by the high water of the Colorado river. To meet that condition all the lands are to be pro- tected against the river at flood by levees of earth constructed on both sides of the Colorado and the Gila. This condition, again, makes it necessary to provide for drainage, and accordingly a system of drainage canals is provided. Again, the topography of the lands is such that some of them cannot be reached by water conveyed in the irri- gation canals, so that pumping plants are planned to be established to pump water up, to those lands. And again, some of the lands are so low that they cannot be drained by gravity so that pumping plants are provided for in the plans to pump this water out and off those lands. The power for these pumps is to be developed by water power, either at the dam, or on the course of the canals, or both.
 ''It is thus to be seen that the plans contemplate works to bring water from the river to the lands, and levees to guard the lands against the water from the river; canals to bring water to the lands and canals to drain it away; | pumps to lift water to the higher lands | and pumps to lift the water away from and out of the lower lands.
 "The Gila will have to be crossed | above Yuma. This will be effected by | a concrete syphon some 3000 feet long, | under the river bed. All the works are | planned to be of the most substantial | character and designed for the highest degree of efficiency for the pupose in tended. It is estimated, tentatively, that the works proposed to be con- structed by the government will cost about s35 per acre of lands reclaimed"