Arizona republican., 1920-02-18

three feet. From May, 1919, to Octo- 1 Der, 1919, it was 2.5 feet On the north | side of the river where there has been
 but a limited amount of pumping there
 was an average rise in the water table | of about one foot from May, 1918, 10 October, 1919. These results show con clusively that the elevation of the ground water on the south side can oe controlled by pumping. and that it is only necessary to pump a sufficient quantity to maintain the water table at a safe depth below the surface. In the vicinity of the Grand canal. north of Phoenix the beneficial effect i of pumping has also been clearly shown during the past few months. As shown by the curve, drawing ~. 4, 1926 acre feet of water was pumped from this area from September ]. 1919, to January l, 1920. An additional 19. l acre feet was pumped during January. making total of 1493 acre feet to February 1st. Readings on the depths to ground water were taken during the first part of February to determine the effect of this pumping. The re- suits show an effect from the four wells, over a territory at least two and one half miles east and west by one and one-half miles north and south. . total area of 2400 acres. Some obSer- yations seem to indicate an effect stiIl farther south, but the amount of this cannot be determined until the pumps have been operated for a longer perloo of time. The average of reading on 25 test wells over the 2400 acres shows the ground water to be approximately four feet lower now than in May, 1919 and 2.4 feet lower than in October. 1918.
 The fact that ground water. over the entire north side, as shown by the curve, drawing No. 4, has remained at practically the same average elevation shows conciusive1y that the lowering on the 2400 acres is due to the opera tion of the pumps. Along the town Ship line-Nineteenth ayenue-in the vicinity of the Grand canal, as shown by the average of the readings of six wells, the water table has risen 0.4 feet since May. 1919.
 Areas Where Drainage Is Needed
 There are five principal areas on the project where drainage is needed. These for convenience have been de- signated as follows:
 1 Southside area. Lying south and east of Tempe
 9 Laveen area Lying south and southwest of Laveen.
 3. Salt river area. Lying north of the river and west of Phoenix.
 4. New river area. Lying east of New river and south of Peoria.
 5. Arizona and Grand canal area. Lying under Arizona and Grand canals northeast of Phoenix.
 The southside area comprises that portion of the project lands adjacent to the Tempe district. Conditions here are similar to those farther east, where the ground water has been lowered by pumping. The soil of this area, as shown by the logs of various wells, is underlaid by caliche 10 a depth of about 50 feet. Below the caliche porous water bearing gravels are found. The high ground water is due to the upward pressure from the water bearing strata below. The most effective plan for lowering the ground water is to carry it out of the porous strata by means of pumping. Drains cut in the caliche cannot be made deep enough to tap the real source of ground water, and consequently are not effective
 The Laveen area comprises a flat depression, about one mile in width at its widest part. lying under the lower portion of the Western canal. The formation consists principally of clay and caliche. These are broken by thin strata of sand. gravel. and noun tain wash. through which ground wa ter slowly Dercolates to the lower DOT ton of the area. There are no deep beds of porous gravel, like those de-