Laserfiche WebLink
<br />8 <br /> <br />C~ Salt balance in an irrigation system simply means that the <br /> <br /> <br />~ amount of salt returned in drainage waters is equal to the amount <br />"'" <br /> <br />~ of salt in the water applied to the land. An irrigation system <br /><.oJ <br /> <br />that is in salt balance neither accumulates salt in the soil nor <br /> <br />leaches salt from the soil. As proposed in this situation, the <br />equivalent salt balance program would insure that water delivered <br />to Mexico would have the same salt concentration as would exist if <br /> <br />the projects in the United States which divert from Imperial Dam <br />and have drainage returns to the river were in salt balance. <br /> <br />Equivalent salt balance would be obtained by bypassing some <br />of the irrigation return flows from the Wellton-Mohawk Project and <br />substituting therefor a combination of better quality groundwater <br />from the Yuma Mesa, and additional releases from Imperial Dam. Even <br />with equivalent salt balance, there would be an increase in salinity <br />concentration between Imperial and Morelos Dams caused by evaporation <br />of a portion of the applied irrigation water on lands in Arizona <br />and California, i.e., the tons of salt applied to, and returned <br />from, the land are equal, but the amount of return flows are only a <br />portion of the applied water. <br /> <br />The deliveries under the equivalent salt balance proposal for the <br /> <br /> <br />first year would have been 130,000 acre-feet per year beyond the Treaty <br /> <br />requirements. The source of the additional water would be releases of <br />Colorado River water from storage above Imperial Dam and from wells on <br />Yuma Mesa near Yuma, Arizona. In 1971 salinity of the Wellton-Mohawk <br />drainage water was approximately 3700 ppm and it is anticipated that the <br />amounts of substitute water would diminish in future years as <br />