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0J1326 the reservoirs were within 3 ppm for the mean and 1 ppm for the standard deviation. The results for the 0.06 bank storage coef- ficient were subsequently used since a positive, nonZero coeffi- cient is physically more satisfying. ~ Inspection of Figure C-25 indicates computed 1968-1970 values to exhibit different properties. All values are negative, indicating unaccounted for salinity diversions. The effect is apparently due to the present modified salt masses at the Hoover station. As noted in the River Basin System Configuration section, Node l8 was introduced to allow inclusion of the ungaged inputs upstream from both reservoirs. This is a practical necessity since details are lost because of inadequate data. In addition, Node 19 was added below Parker Dam to allow both CAP and t~~D demands to be satisfied by operating Lakes Powell and Mead. Although required by program convention, this approach has no effect on salinity results. However, the addition of CAP and r~~D downstream could result in Parker Dam capacity restraints preventing the full release. In practice, this did not occur for the runs described in this report. ~ L Parker-Imperial Reach The upstream and downstream stations for this reach are the Colorado River below Parker and at Imperial Dams. Storage behind Imperial Dam is insignificant and the reach was treated as a river reach. Results are given in Tables C-28 through C-30 and in Figures C-27 through C-29. Figure C-27 suggests unaccounted for diversions occurred during 1968-1970. Although the Lower Colorado Indian Res- ervation and the Palo Verde Irrigation District were not explicitly considered and are therefore included in the ungaged value, this difficulty is probably related to the peculiar salt mass results for the same years in the Hoover to Parker reach. Both the monthly values for each year and the mean monthly values for the entire run were used in obtaining a base run. , ~ Summary - All Reaches I. t r Means and standard deviations for flows and salt mass are summarized in Table III. t, Fundamental Differences Between Network r,lodel and Biennial Report t,lethod A consideration bearing on the difficulties in computing ungaged trib- utary inputs are the fundamental differences between the network model and the Biennial Report method. [1] In the Biennial Report, historical data at a given station are merely adjusted or modified to reflect additional projects. Ungaged inputs are not explicitly considered, and are in effect assumed unchanged, being embodied in l6