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<br />w <br />w <br />~ <br />w <br /> <br />damage reduced.ll Moreover, without cost estimates (however crude <br /> <br />they may be), there is no opJ;>ortunity to see that some of the more <br /> <br />attractive options--particularly those nonstructural options con- <br /> <br />cerned with decreasing the agricultural salt load--may deserve more <br /> <br />attention than they receive in the report. <br /> <br />Turning to the third point I welcome the Forum's presen- <br /> <br />tation of the concept of a salinity baseline against which to <br /> <br />measure (or track) the effects of basin development, land use <br /> <br />change, and the effectiveness of control efforts. But I can only <br /> <br />wonder at the choice of a simple two variable linear regression <br /> <br />relating flow to total dissolved solids (TDS) as the model for <br /> <br />the baseline. I am further puzzled when the report states that a <br /> <br />two standard deviation band' about the regression line will consti- <br /> <br />tute the baseline range. This broad band is defended as necessary <br /> <br />given the great variability of the relationship and the importance <br /> <br /> <br />of so many other factnrs in influencing the effect of flow on salt <br /> <br />load. But the explanation is entirely unacceptable and, as a <br /> <br />consequence, the simple two variable relationship is unusable. If <br /> <br />other. explanatory variables (~, land use, soil type, average <br />slope, presence of natural sources, etc.) might aid in refining <br /> <br />the relationship they should be included. Without them, or with- <br />out some effort devoted to refining the regression expressio~, the <br />baseline will be of very little value in monitoring the river <br />basin and explaining the effects of change and development on water <br /> <br />31 See, for example, Bureau of Reclamation, "SUlnllIary of <br />Activfties of the Water and Power Resources Service" Presented to <br />Colorado River Salinity Control Advisory Council" Santa Fe, New <br />Mexico, September 19-80, and Howe, C., "Colorado River: -Lower <br />Basin Benefits and Costs from Upper Basin Salinity Reduction Pro- <br />grams (Draft)," for DRI, Denver, Colorado, January 1981. <br /> <br />24 <br />