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<br />00184~ <br /> <br />(8) Inaccuracies of stream gaging measurements can produce ungaged <br />flow errors of the same order of magnitude as the true ungaged inflows. <br /> <br />(9) Averaging time-dependent hydrologic data over longer and <br />longer time periods reduces the variance for the entire period. <br />Thus mean yearly concentrations will exhibit less variance than <br />mean monthly, while mean weekly, daily, or hourly values will <br />result in a greater variance. <br /> <br />(10) Concentrations contained in the Biennial Report are a hybrid <br />of straight or time-weighted means and flow-weighted ones. For <br />natural streams, mean time-weighted concentrations are higher than <br />mean flow-weighted, while the hybrid method gives intermediate <br />values that are closest to the flow-weighted ones. For reservoirs, <br />differences are insignificant. <br /> <br />(11) Concentrations at a given station are not normally distributed. <br />This is readily apparent when standard deviations are compared to the <br />means since they are often on the same order of magnitude. <br /> <br />(12) Although fluctuations of Lakes Mohave and Havasu are minor, <br />both reservoirs had to be modeled to obtain realistic results. <br /> <br />(13) Identical qualities at Imperial Dam were obtained for the <br />base condition when 0.0 and 0.06 bank storage coefficients were <br />used for Lakes Mohave and Havasu. Thus, results at Imperial are <br />insensitive to reasonable bank storage coefficients for these <br />reservoirs. <br /> <br />(14)' Comparing results of runs in which reservoir storage changes <br />are radically different can be very misleading. <br /> <br />(15) Initial reservoir salinities affect concentrations at Impe- <br />rial Dam during early times, but the effect rapidly diminishes. <br />Salinities are within 5 ppm within 10-14 years using different <br />starting salinities. <br /> <br />(16) l'/hen monthly releases are a large percentage of the current <br />reservoir storage volumes, lagging outflow concentrations can pro- <br />duce unreasonable results. The modified approach described in the <br />report is believed superior. <br /> <br />(17) Use of mean operating plans for various future projects <br />results in minor deficiencies in flows at the upstream bound- <br />aries. They are insignificant in the context of total flows. <br /> <br />(18) Salinities at Imperial Dam will increase under further <br />development, reaching 1,258 ppm for full development. <br /> <br />35 <br />