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<br /> <br />N <br />...... <br />co <br />...... <br /> <br />quality data to be representative of the longer period of data. A <br />graphical correlation of quality concentration versus flow was drawn <br />for each station, The slope of this relationship was then used to <br />adjust the quality means to 'be representative of the adjusted <br />streamflow data. ' <br /> <br />3.2.2 Adjustment of Variance <br /> <br />An exact estimate of the true variance of the data would be more <br />difficult than an exact estimate of the means, One complicating <br />aspect is that only a few of the selected flow stations were actually <br />in operation during the entire 1914-1965 period, Because of time <br />limitations, it was decided that the coefficient of variation, <br />standard deviation divided by the mean, would be used to obtain <br />adjustments in the variance, Analyses of data for different time <br />periods indicate that the coefficient is relatively stable and <br />only provides a reasonable estimate of the variance of the data. <br /> <br />Where reservoirs caused a major change in flow and quality data, the <br />data used for the data base and adjustments were those for the period <br />before the dams were closed. <br /> <br />3.2.3 Qualifications of Stochastic Data Base <br /> <br />The present data base should only be considered as a reasonable <br />representation of flows and quality in the Colorado River Basin. As <br />such, they should be suitable for preliminary evaluation of different <br />alternative futures for the basin and determining their impact on <br />quality, For decisions beyond this level, however, it should be <br />recognized that the data are only a reasonable estimation of flows <br />and quality in the system. <br /> <br />\ <br />\ <br /> <br />A more comprehensive analysis of the available data should be made <br />to improve the estimate of the means and variance and to test the <br />distributions used for the random component, Similarly, a more <br />intensive study should be made of the interrelationship between flows <br />and quality to predict how quality will vary in the future. The <br />indicated trends of the quality naturally improving with time can be <br />of considerable importance regarding the different futures for the <br />Basin, Techniques and the data are available for this needed further <br />analysis. <br /> <br />This comprehensive analysis would still not clarify or answer all the <br />problems exhibited in the data. Basically what is needed is an <br />extensive analysis of all data in the basin to evaluate the data for <br />each of the river reaches, to determine man's effect on the data, <br /> <br />18 <br />