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<br />. <br /> <br />. <br /> <br />water will allow the Salton Sea to reach ocean salinity. Figure 4. This would create a <br />smaller Salton Sea by about 35% (to 245 square miles) with an elevation only about 3 feet <br />lower than pumping in 400 TAP/year and pumping out 500 TAP/year. Our estimate of the <br />capital cost for this system is about $300 million, with operating costs being approximately <br />$5 million per year. <br /> <br />Therefore, "pump-out" achieves nearly the same result as "pump-in, pump-out," and at a <br />much lower cost. Providing that a smaller Salton Sea by approximately 35% is acceptable, <br />"pump-out" should be considered as a viable option for the Salton Sea. <br /> <br />One important issue that needs to be resolved with this concept is the destination of the <br />pumped water. One frequently mentioned area is the Laguna Salada in Mexico. <br />Technically this is feasible, but would entail reaching an agreement with Mexico. Another <br />important issue with "pump-out" is that the salinity level would increase for about 25 years, <br />hitting a peak of about 65 ppt before decreasing. Figure 5. <br /> <br />Diked Impoundment <br />Another concept that has the potential for controlling salinity and elevation is the creation of <br />in-Sea impoundment areas by diking. This could result in a Salton Sea with the same <br />elevation as now and a salinity level comparable to that in the ocean. The primary <br />disadvantage of "diked impoundment" is that part of the surface area in the Sea would be in <br />an impoundment area which would contain very saline water. Fish would not be able to <br />survive in the impoundment, and in time this brine would precipitate salt. <br /> <br />Eventually, this salt would have to be removed from the impoundment area--the cheapest <br />way probably being to pump out the brine. When this has to be done is uncertain and will <br />depend on the criteria for pumping out the brine. A lower bound would be when the brine <br />first reaches saturation while the upper bound would be when the impoundment area fills <br />up with salt. <br /> <br />Using our assumptions on inflow volumes, an impoundment area of about 10% of the area <br />of the Salton Sea (approximately 35 square miles) would allow the Salton Sea to reach <br />ocean salinity. Figure 6. An estimate of the cost of an earthen dike is about $300 million-- <br />however, such a dike would only provide salinity control and the Sea could ultimately be <br />reduced in area by about 20%. A larger, reinforced dike with an impoundment area of <br />almost 30% of the present Sea would be required to maintain the existing shoreline. Figure <br />7. A reinforced dike providing both salinity and elevation control would probably raise the <br />capital cost by more than a factor of two. Operation costs would be approximately $2 <br />million/year. <br /> <br />If having part of the Salton Sea at a high salinity level is acceptable, we feel that "diked <br />impoundment" is also a viable option for the Salton Sea. <br /> <br />CONCLUSIONS <br />Based on our analysis, we conclude that: <br />. Desalination is not a viable concept for salinity and elevation control of the Salton <br />Sea. <br />. "Pump-out" is a feasible method for salinity control, but the size of the Salton Sea <br />could decrease by approximately 35%. Furthermore, the Sea would continue to <br />increase in salinity for about 25 years. <br />. "Diked impoundment" could control salinity and elevation if the dike is reinforced <br />to serve as a dam. If the dike is earthen, the size of the Sea could decrease by about <br />20%. In either case, the impoundment area would have high salinity water. <br /> <br />4 <br />