OCR Text |
Show -12- they have in most instances during the past sixty years, the year 1955 should be the last year of extremely low flow for some time to come. Besides these periods of increasing or decreasing flows, periods of relatively high and low flow are also more evident. Again, the proportion of years of high flow of forty percent as against sixty percent of the years of low flow is verified in this 60-year record. The present trend of 10-year means is certainly upward. The indications are again that an average virgin flow of 14,-000,000 acre feet may very likely be attained in another ten or twelve years, and again, the upward and downward trends indicate that the upbuilding will probably last from fifty to one hundred percent longer than the descent to a minimum. The curve outlined in red is much smoother than the blue curve just described. This red curve shows successive 20-year averages. Again, the periods of relatively high and low flows are indicated with the same maximum year 1923 as before, but the minimum point for the 10-year average curve was in 1940, while for the 20-year average curve, it occurs ten years later, in 1950. There is also an upward trend for the last five years on this curve with indications that it may reach an average of 14,000,000 acre feet in about ten years. Only, however, with more years of records can it be determined for certainty whether or not these probabilities will become actualities. Final Hydrograph, Last Twenty-Five Years The last hydrograph in this series covers only the last twenty-five years, 1930 through 1955. This running-average curve is colored in orange with the mean for |
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] : |