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USBR and the Washington County Water Conservancy District would be, of course, a necessary adjunct to this exchange application. The second water right would be a normal application to appropr- iate water from the Virgin River below La Verkin Springs during the non-irrigation season. The use could be described as salinity control." Based on the above discussions of clay and water rights it does not appear that resources should be a limiting factor for this project. AL TERI1h T I VES Seven alternatives were examined, and cost estimates developed. Since this pruject had been previously studied (1981 Concluding report) at feasibility grade, the feasibility designs and cost estimates for features common to both the old and new alternatives were considered to be representative of true costs once they were inaexed to 1983. The seven alternatives are divided into three basic groups; (1) those employing a desalinization process, (2) those employing total evaporation of the saline spring water without utilizing the upper diversion structure of ~C"CD's proposed Quail Creek Dam and Reservoir project, and (3) total evaporation utilizlng the Quail Creek project upper diversion structure. The Alternatives within each of the three major subdivisions differ only in the composition of the lining used in the brine or evaporation ponds. A reexamination of potential evaporation sites available in the area showed that the Purgatory Flat area was still, as discussed in the 1981 Concluding report, the best site to build evaporation ponds. The following presents a comparative description of the alternatives (Table 3). A. DESALI~IZATION ALTERNATIVES (Alternatives 1-3) This plan (Figure 1) isolates and re~oves the saline springflow from the river, desalts it, returns the product water to the river, and disposes of the brine in 612 acres of evaporation ponds. During high river flows, occurring only about two percent of the time, the desalting plant would be shut down and the river would flow over the upper diversiun structure, thrut:sh the springs area, and througn the open gates of the low~r diversion s truct\... re. Diversion Facillties: To isolate the springs a concrete upper diversion struct~re (a~out 229 feet long an0 20 feet hi5~) would bE bLllt 01, lhe Virgil' F:iver just abGve the La Verkin SprlllgS, ano a gated concrete luwer diversion structure (about 210 feet long allo 22 feet high) woulo be built below the springs area. The riverflow would be diverted around the springs through a burieo gravity flow bypass pipeline (2500 feet long and 132 inches in diameter) and returned to the river channel below the lower diversion structure. Desalinization F.cilities: The springflow would be ponded between the diversion structures one then transported by grcvity through a corrosion 4 '-"(\1')6"'1 I:,).;. 'j,j