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Zeutschel OS7000, 400 dpi, 8 bit, 8,887,832 bytesof this drainage basin. The method referred to is that of obtaining a factor of increase in precipitation due to elevation by a comparison of the records of rainfall at various stations in this part of Arizona. The stations available for this purpose were: Florence, Fort McDowell, Fort Apache, Fort Lowell, Phoenix, Breckenridge, Fort Grant, Fort Verde, Prescott, Fort Buchanan. Of these stations, two-Florence and Phoenix-are situated out on the plains far away from the mountains, are not topographic parallels, and should not be used. The following shows the increase of rainfall with each 100 feet rise in elevation with Fort McDowell as a base: Increase of rainfall with altitude Station. Length of record. Elevation. Elevation above McDowell. Measured Rain. Constant Increase per 100 feet rise. Yr. Mo. Feet. Feet. Inches. McDowell 23 10 1,250 - 10.38 Base. Lowell 19 5 2,400 1,150 12.37 .17 Breckenridge 6 10 3,800 2,550 17.03 .26 Fort Grant 17 2 4,860 3,610 16.85 .18 Fort Buchanan 3 11 5,330 4,880 21.58 .27 Fort Apache. 18 10 5,050 3,800 21.04 .28 Verde 22 3,160 1,190 13.13 .15 Prescott 23 11 5,390 4,140 17.06 .16 1.47 Mean .21 The greatest range of this constant is from 0.28 per 100 feet rise for Fort Apache to 0.15 at Fort Verde. Using the former constant with Fort McDowell as a base gives a rainfall for Silver King of 18.1 inches. Assuming as the constant increase in precipitation for each 100 feet rise in elevation 0.21 of an inch, we have for Silver King, at an elevation of 3,650 feet, a rainfall computed thus: Feet. Silver King, elevation 3,650 Fort McDowell, elevation1, 250 Inches. Rise...2,400 X 0.21 - 1005.04 Mean rainfall at Fort McDowell 10.38 Increase for Silver King 5.04 Computed mean rainfall at Silver King 15.42 In view of the fact that, as above stated, Fort McDowell has the longest record of any station in the vicinity of Silver King and is most nearly comparable with it topographically, and that this computed rainfall is conservative as compared with that arrived at above by comparison with other stations, and by comparison of actual observations, the rainfall at Silver King is assumed in round numbers as 15.4 inches, and this determination, while of course rough, is considered amply conservative and the best obtainable with the present information. It is taken as a basis for the computations to follow, of the run off of this basin, and can be improved only by further observations of rainfall and measurements of the discharge of Queen Creek at the proposed dam site extending over a considerable period of time. The importanc