| OCR Text |
Show PART IV RESOURCE AVAILABILITY Water In order to ascertain the amount of water remaining over and above present (1965) uses, reconstruction of present modified flows was accom- plished in each of the three subregions for the study period 1914 to 1965, the premise being that the general hydrologic conditions of that period might reasonably be expected to reoccur in the future. The 1914-65 study period was selected as the longest period for which reliable records were generally available in the region. The pro- cedure is one of adding to the historic annual flows at the outflow points of each subregion past annual depletions, the result being vir- gin or undepleted annual outflows. Then, assuming that all present uses were in effect throughout the 1914-65 period, the present (1965) normal- ized use in the subregion was deducted from the virgin flow, the result being the present (1965) modified flow. In each subregion the studies reflect the use of waters produced locally within the subregion. In other words, the flows of the Green River and the Colorado River at their con- fluence are not considered a local inflow to the San Juan-Colorado Subre- gion. The data from the three subregions can thus be summed up to ascer- tain the respective results at Lee Ferry, the outlet of the total region. In the study no attempt has been made to account for changes or differ- ences in natural losses, sometimes referred to as "salvage." A consider- able amount of such salvage water, however, is accounted for in the com- putation of reservoir losses in the Main Stem reservoirs. Water supply available in Upper Colorado Region (Unit-1,000 acre-feet) Green Upper San Juan- Upper River Main Stem Colorado Colorado Subregion Subregion Subregion Region Virgin water supply (191^-65) 5,^60 6,806 2,606 14,872 Level of depletions (1965) 993 1,397 hlQ 258o8 Modified fXow (191^-65) (excluding main-stem evaporation) k,k67 5,^09 2?l88 12,06U Main-stem reservoir evaporation normalized (1965) 67 ~ 576 6^3 Residual fl.ow ^,1+00 5,^09 1,612 11,^21 |
