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... 3. Operational Decisions. Neither the "water balance" nor "Kc-ETo" approach is sufficiently accurate to serve alone as the basis for district-wide operational decisions on a day-to-day or week-to-week basis (Le., predicting needed diversions). 4. Efficiency Estimation. Neither of these methods directly give an estimate of irrigation efficiency (IE) or its accuracy. Some additional analyses must be performed to estimate beneficial uses other than ET such as leaching. Methodology for estimating the magnitude of beneficial uses such as leaching and runoff need to be reviewed critically and agreed upon by lID and USBR. 5. Reasonable Practices. Is it justifiable to conclude that current irrigation practices in lID are unreasonable? The answer is no. As Dr. Jensen stated in his report, reasons for the apparent trend of increasing flows to the sea are not known, but further study of "reasonable" and beneficial uses may be necessary. Independent detailed studies of the economics and physical feasibility and reasonableness of modifications to current irrigation practices/infrastructure are required to answer the question posed, and such studies have not yet been done. Conclusions concerning the reasonableness of alternate irrigation practices, and recommendations to change existing practices on the basis of perceived unreasonableness, cannot be justified until such analyses are done. 6. Trends. Is it justifiable to conclude that there is a trend of declining irrigation performance in lID? This question has not yet been answered. While irrigation efficiency estimates for recent years may seem to follow a trend, the data need to be statistically analyzed and appropriate confidence levels assigned before any such conclusion can be made. Until this is done, the existence of statistically valid trends is still an open question. 7. Salton Sea Level Fluctuations. Are changes in lID efficiencies the primary cause of Salton Sea water level fluctuation? It does not appear so. Of course, inflow from lID affects the Salton Sea level. However, as shown by the attached figure, assembled by Dr. Jensen in November, 1996, weather and rainfall have a major impact on changes in the Sea level. Evaporative demand minus rainfall is correlated with, and similar in magnitude to, changes in the Salton Sea level. Dr. Jensen has indicated that Figure 2.2 and associated comments regarding the Salton Sea found in the Jensen report would be rewritten if done today. 8. Indications of Accuracy. Is it reasonable to draw conclusions from year-to-year changes in efficiency? The answer is no, unless ~ statistical analyses, which were not included in the Jensen report, are performed. Our ability to understand the lID hydrologic system and to draw conclusions must be tempered by our ability to quantify and verify both trends in, and magnitudes of, various w~ter volumes and irrigation performance indicators. Therefore, estimates of values or performance indicators should always be accompanied by an indication of accuracy (Le., by confidence intervals).