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<br />3~83 <br /> <br />110, CVWD. and MWD have used these various eftlciency calculations as cvidence <br />supporting or refuting assertions of reasonable amounts required for beneficial use, <br />Estllnates of lID eCficiency ranged between 69% (MWD Sunmlary, May 2003, p. 31) and <br />83%, (liD Bnef, 2003, p.2I), as calculated by each of the various entities' expel1s. <br />Reclamation's review of the submissions indicates that each of the entities took a unique <br />approach to the calculation Itself, making direct comparisons between the submiSSIOns <br />difficult. When individual calculations are closely examined, it is apparent that each <br />expert included different components in the numerator and denominator of their <br />efficiency fomlUla. Reclamation prepared independent calculations ofmigation <br />efficiency. <br /> <br />Efficiency Over Time <br /> <br />The estImates of efficiency presented in the preceding paragraph represent an average <br />estimale for a specific period of time, Reclamation prepared additional analysis to present <br />an overall district-wide gross composite of water use within IID. Although consistent <br />measurements of falm deliveries, tailwater and leach water are not available, <br />measurements of district-wide inflows and outflows are available, A twenty- year period <br />from 1983 to 2002 was examined. Official Decree Accounting consumptive use data <br />prepared and maintained by Reclamation for IJD were used as representing the gross <br />inflow to the District Gross outflow values from IID for the period 1987 through 2002 <br />were provided from Jensen/Walter Supplement, 2003, Appendix D, page 2. Jensen and <br />Walter removed the affects of contributions from groundwater inflows, and from Mesa <br />510nn drainage in order to anive at a data set of estimated gross outflows that reflect liD <br />water use alone. This gross outflow data was then extended back through 1983 by using <br />additional available data (Redlinger, July 2003). <br /> <br />Figure 4 shows the adjusted outflows and the gross net use for lID over the past 20 years. <br />To provide a consistent and fair comparison, the data used to develop Figure 4 below was <br />adjusted to reflect conservation programs implemented under the ffD/MWD water <br />consetvation program. In the early years, prior to the initial 1988 IID/MWD conservation <br />program, both the gross inflow aud gross outflow were reduced by 104,940 acre- feet, <br />while in later years the amount of reduction reflected the difference between the amount <br />achieved under the lID/MWD conservation program and 104,940 acre- feet. This figure <br />shows that the gross net use has increased at a slower rate over time than the adjusted <br />gross outflow. <br /> <br />July 2, 2003 <br /> <br />32 <br /> <br />Detemlinatiol1S and Recommendations <br />For liD - Calendar Year 2003 <br />