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<br />water would probably be a little higher in TDS due to reservoir <br />evaporation. <br /> <br />H. The effect at I~per1al Dam can be estimated by the future effect <br />equation for year 2010 as described in Progress Report No. 11 <br />(January 1983). <br /> <br />I. The3existing water quality (TSD in mg/L) and average flow data <br />(ft /sec) adequately represent the expected long term average <br />conditions that exist at the following points in the river system <br />(Figure 1). <br /> <br />A. Above La Verkin Springs (703 mg/L; 8~ft3/sec.) <br />B. La Verkin Sprin9S (9919 m9/L; 10.9ft /sec.) <br />C. Virgin River near St. George (2133 mg/L; 138ft3/sec.) <br />o. Littlefield Springs (2920 mg/L; 60ft /sec.) <br />E. Virgin ~i\'er at Littlefield (gage) (2325 mg/L; <br />216ft /sec.) <br /> <br />J. The flow of La I'erkin Springs is assumed to be 10.9 ft3/sec. <br /> <br />K. A reduction in salt loading at the Littlefield gage would be <br />fully realized at Lake Head. This assumption is probably <br />optimistic since irrigated agriculture exists belov: Littlefield <br />gage. <br /> <br />I V. PROCEDURE <br /> <br />The procedure used was to define the study area, determine the major <br />gages, and define all r,ajor inflows, outflO\"iS and intervening flov!". <br />Tner, t',e flov. dnerted frOIT, La 'verkin Sprir,~s by !f,e project WaS <br />replaced with water from Quail Creek Reservoir, the system was <br />rebalanced and the d1fferences in salt loading to Lake Mead <br />extrapclated to a selinity reduction at Imper1al Dbffi using the future <br />effect equations found in Prc,gress Report f11 (January 1963). A step <br />by step outline of this process follows; <br /> <br />A. Define the beginning of the study area as above La Verkin Springs <br />ant the eno as Vir~in River at Littlefield (~age). <br /> <br />r <br />c. <br /> <br />CcrsiciE:l~ tht ~';r~lr F,lver nt:ar St. GE:C'fgt: (~c'~~.' tc' represE:l<t <br />tht midpoint in tne system below La Verkin Sprlngs and above the <br />region where infiltratiun takes plaCE. <br /> <br />C. Construct e conceptual sche~atic of th~ study area (Figure 2). <br /> <br />D. Calculdte the intervening Virgin R1ver flov: betWEen a~ove La <br />Verkin Springs and Virgin River Near St. George in ft /sec. and <br />tons/year for each major ion of TDS as shown below (Table 2): <br /> <br />3 <br /> <br />002617 <br />