OCR Text |
Show -6- The only difference between these quantities and those given in the Storage Project Report is that beginning with the year 1952 the equivalent irrigated area was increased from 1,385,000 acres to 1,400,000 acres. This increase of 15,000 acres is purely arbitrary, and is used because all the evidence points to the fact that in recent years, probably earlier than 1952, the total irrigated area has become materially larger. It will be seen by observations of this hydrograph that the irrigated area used for the computation of man-made depletions has increased from about 310,000 acres in 1896 to approximately 1,400,000 acres at the present time. The mean virgin flow used in the computation of man-made depletions was based on the period 1914 through 1945 which was 15,638,000 acre feet as used by the Engineering Advisory Committee to the Upper Colorado River Compact Commission, allowance having been made for equivalent uses other than for irrigation. The minimum historic flow during the 60-year period covered by this study amounted to 4,400,000 acre feet in 1934 with a maximum five times as great in 1907 amounting to 22,000,000 acre feet. The estimated virgin flow in the minimum year of 1934 was 5,650,000 acre feet with a maximum four and a half times as great, or 24,000,000 acre feet in 1917. All these values are rounded figures. The above minimum virgin flow was a little more than one-third (37%) of the 60-year average, while the maximum virgin flow was about fifty-seven percent more than the average. The wide variations in the annual discharges are so great that it is extremely difficult to work from such a table or graph. Consequently, average figures for the available water supply are usually computed and used in the planning of projects |
Source |
Original book: [State of Arizona, complainant v. State of California, Palo Verde Irrigation District, Coachella Valley County Water District, Metropolitan Water District of Southern California, City of Los Angeles, California, City of San Diego, California, and County of San Diego, California, defendants, United States of America, State of Nevada, State of New Mexico, State of Utah, interveners] : |