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Zeutschel OS7000, 400 dpi, 8 bit, 9,145,512 bytesthree can be found which furnish a record of considerable length and are brought up to date. These are Fort Grant, with a record beginning with 1873, San Carlos, beginning in 1881,, and Willcox, beginning in 1880,. The altitudes are 4,860, 3,456, and 4,164, and they are fortunately also fairly well distributed geographically. It may fairly be assumed that the mean precipitation of these three stations bears a constant ratio to the mean precipitation of the basin. Exactly what that ratio may be can not, of course, be known, nor does it signify, provided only that it be constant, as assumed. The mean annual rainfall at each station, the mean of the three, and the total run-off for the two years in which it was measured are given in the following table: Rainfall and run-off in Gila Basin. Year. Fort Grant. San Carlos. Wilcox. Mean. Measured run-off. Inches. Inches. Inches. Inches. Acre-feet. 1881- 82 19.25 16.00 6.22 13.32 - 1882- 83 14.06 11.32 9.50 11.63 - 1883- 84 18.35 15.77 8.60 14.24 - 1884- 85 16.76 14.26 14.12 15.05 - 1885- 86 14.33 10.93 8.53 11.26 - 1886- 87 23.51 7.56 14.64 15.24 - 1887- 88 11.94 8.99 11.60 10.81 - 1888- 89 17.74 15.01 14.20 15.65 - 1889- 90 14.30 17.12 15.15 15.52 366,593 1890- 91 14.30 15.67 9.95 13.31 - 1891- 92 9.45 13.03 8.59 10.36 - 1892- 93 10.07 10.47 4.65 8.40 - 1893- 94 14.12 9.70 5.09 9.64 - 1894- 95 11.69 9.31 7.58 9.53 - 1895- 96 12.41 14.45 6.76 11.21 623,069 ---- Mean 14.82 12.64 9.68 12.38 - The first year for which the run off was measured, 1889- 90, has the highest precipitation in the record, except one, which occurs in the year previous, and would somewhat affect the measured run off. From this fact, it might be well supposed that the run off for that year ought to be the maximum. But the year 1895- 96 has a much greater run off, while the mean precipitation for that year is one of the lowest in the record, being considerably below the average. This apparent anomaly only emphasizes the well-known fact that the percentage of run off is very greatly affected by the manner of the precipitation, whether in sudden showers, which favor a large absorption and subsequent evaporation. In a basin so extensive and of such various topographic features as the one under consideration, the locality of the rainfall may also strongly modify the percentage of run off. It thus seems to be impossible to arrive at an accurate estimate of the run off of this basin without actual measurements extending through a long series of years. In the light of the ascertained facts it is conservatively estimated that an annual supply of about 150,000 acre-feet from this reservoir might be relied upon, leaving a capacity of 50,000 acre-feet, to be eventually filled with slit. It is estimated that with careful use 2 acre-feet of water might be made to serve an acre of land, including all loses by seepage and evaporation. It is also assumed that it would be a desirable eventually to use 20,000 acre-feet on the Indian reservation, and this amount should be set aside for that purpose