Arizona republican., 1906-03-07
OFFICIAL DESCRIPTION
 OF YUMA PROJECT
The Difficulties Which the Reclama. ton Service Has to Surmouut.

The reclamation service has issued the following description of the Yu- ma project:
 Especial interest attaches to the Yu- ma project in Arizona and California, one of the great national irrigation works now we'll started by reason of the unusual physical conditions of that section of the southwest and the some- what unique engineering problems which are involved.
 Physically and climatically, the Coll orado delta is singularly like that of the Nile. Like the great river of Egypt the Colorado river rises in far distant mountains and empties through great tidal flats into an inland sea, Its vaI- ley and climate all bearing out the likeness. The Colorado is one of the, great rivers of the arid west r. drains an area of more than 225, 900 square miles and pours a turbid flood into the Gulf of California for hun dreds of miles. It has cut it's chan mel more than a mile deep through the plateau carving out abyssmal can yons, which are the most wonderful in the world. In flood its waters car ry in solution millions of tons of silt and detritus which for ages the stream has deposited in the sea, building up a broad delta through which it flows on top of a dyke, so that it's normal channel is elevated considerably above the country on either side. In time of flood it spills over its dyke inundating a portion of it's valley. The engineering works in- voIve a dam across the river, canals on both sides of the stream, and an ex-
 
 lower lands from flooding. The dam known as the Laguna is being con- structed about twelve miles above Yu- ma by New York contractor, and is notable as being the first of its type built in America. The diamond drill lers sought in vain for bed rock for nation in the channel and finally the government decided upon a structure of the East India weir type patterned after the dams built under similar conditions in India and Egypt by the English engineers.
 The Laguna dam will be 4.750 feet long, nineteen feet high, with a max imum width of 265 feet and will con- tain 356,OOO cubic yards of loose rock. It will rest on a foundation of sand and will weigh approximately 800, 000. The settling basin formed by this structure will be one mile wide and ten miles long. To avoid the enormous quantities of silt carried by the Colo rado and which would quickly fill up the canals, the headgates are so ar ranged as to draw off only the top foot of water Into the canals.
 Unprecedented floods during the past year have emphasized the impor- tance of safe guarding the construc- tion of the levees which are required to prevent inundation of valuable low land areas. The problem is complicat- ed. because of the fact that the area to be irrigated is in the drainage basin of two important streams, the GiIa and the Colorado rivers, both subject to sudden and tremendous floods.
 The main canal of the project will cross the valley of the Gila in pres sure pipe passing under the stream The Gila is normally dry, or nearly so, but when in violent flood, frequently changes its course, so that the levees must be placed so as to confine the stream to definite channel before building the crossing, as it might oth- erwise change its course and leave tho crossing to one side. The crossing must be made during the coming win ter and the dykes must be built in the spring and summer.
 The serious nature of the problem which confronts the engineers will be appreciat d when 1t is known that since the Initiation of the work the Gila has twice so changed its channel and the topography of the country by cutting out in places and building up in others that re-surveys and plans of structure have been made and re- made by reason thereof. The leyees are now ready for construction, but until they are completed the uncer- tainty of the behavior of the Gila rem ders it unwise to let the work by con- tract under definite plans, as con- tractors must necessarily be govern ed by the conditions, and their bids will be made accordingly. There is urgent need of haste.
 The secretary Of the interior, recog- nizing these facts and upon recom- mendation of the board of consulting engineers, who investigated the situa- tion, has ordered that the work be un- deTtaken immediately by the reclama- tion service by force account.