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<br />III. ASSUMPTIONS <br /> <br />The following assumptions were used in evaluating this project: <br /> <br />A. The study area can be represented by the schematic in Figure 2. <br /> <br />B. There is an average annual infiltratio~ loss of Virgin River <br />water near Bloomington, Utah, of 60 ft Isec. This is <br />approximately the same flow rate as Littlefield Springs, AZ. <br /> <br />C. If infiltration of Virgin River surface water near Bloomington, <br />Utah, is the sole source of the Littlefield Springs, there will <br />be an improvement in the quality of the Littlefield Spnngs flow <br />after a minimum of 22 years of project life. <br /> <br />TWenty-two years is the calculated m1nimum travel tlme requ'red <br />for water to move through the underground system (Bureau of <br />Reclamation, February 1979). <br /> <br />The assumption that the Virgin River is the sole source of <br />Littlefield Springs is very conservative since the deep carbonate <br />aquifer within the area could be the source or Pdrtial source of <br />Littlefield Springs as could water from any number of otner <br />sources. <br /> <br />Improved qual ity of the Littlefield Springs flow is assumed to be <br />proportional to improved quality in the Virgin River and <br />subsequently decrease the salinity of the Colorado River at <br />Imperi a 1 Dar-,. <br /> <br />C. The water quality data fro~ the gage near St. George adequately <br />represents the quality of the water infiltratlng near <br />Bloomington, Utah. Therefore, if this infiltration is the source <br />of the Littlefield Springs, the salt pickup through the <br />undErground system can be defined as the water quality of the <br />LittlEfield Springs ~inus the water quality of the Virgin River <br />near the St. George gage. <br /> <br />E. The difference in concentration between Littlefield Springs and <br />the flow nEar St. George (salt pickup) does not change from <br />presE:',t for c 11 ic,ns except Ca al,C HCO~. <br />j <br /> <br />Considering Littlefield Spr1ngs flow: Ca and HCO. are at <br />s2tuyttion~ thereforE~ ary change in upstres8 ~atgr quality ~ill <br />net change the concertrati0n of tnese 10ns. <br /> <br />F. <br /> <br />G. The water removed from the Virgir, River by isoldting and <br />diverting the La Verkin Springs 1S replaced by water from the <br />Quail Creek Reservoir, which is presently under construction. <br />For the purposes of this analysis the quality of this replacement <br />water is assumed to be the same as the flow above La Verkin <br />Springs. In actuality the Quail Creek r~servoil' replacenent <br /> <br />2 <br /> <br />OO~G16 <br />