OCR Text |
Show 108 course, the more water that is stored in Lake Mead the more that evaporates. Also, a reservoir must be operated at below its full capacity so that it can be used to impound excessive unexpected flows which may occur in any particular year and thus prevent flooding. Because of considerations such as these Hoover Dam cannot be used to even out fluctuating yearly flows over any considerable period of time. For example, assume, hypothetically, that the average inflow into Lake Mead over a fifty year period could be predicted as 10,000,000 acre-feet per year. In a year in which 17,000,000 acre-feet flowed into the Lake, only 10,-000,000 would be released and the remainder stored to offset future dry years if the purpose was to establish an actual yearly outflow equal to the average yearly inflow during the fifty year period. However, if the reservoir were almost full, prudence would require that more than 10,000,000 acre-feet be released so that the dam could be used to impound any unusually heavy inflows which might occur in the succeeding few years. In a converse situation, if only 8,000,000 acre-feet flowed into Lake Mead in one year, 10,000,000 acre-feet would still have to be released in order to maintain a yearly outflow equal to average inflow. However, if the reservoir were low, it might be wise to release only 8,000,000 acre-feet so as to reserve a supply for the next few years in case the drought conditions worsened. The point is that it is unrealistic to take the average yearly inflow into Lake Mead for a thirty or fifty year period and assume that this, less evaporation losses, will in fact be the actual yearly supply released from Lake Mead. Even if the average for the last fifty years were repeated over the next fifty years, which itself is uncertain, nothing supports the conclusion that the yearly average would or could be translated into actual yearly releases. |
Source |
Original Report: State of Arizona, complainant v. State of California, Palo Verde Irrigation District, Imperial 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 |