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<br />f-6 <br />00 <br />-.J <br />o <br /> <br />", <br />., <br /> <br />Wilcox (1955) in his classification of RSC values indicates that values <br />Jess than +1.25 should be safe. The values of RSC for the projected water are <br />well below the 1.25 marginal value. This should not cause problems. It should <br />be noted at this point that the chemical analysis of HCO; in the published <br />data were scattered and the regression equation had a correlation coefficient <br />of only 0.19. However, if the most active concentrating mechanism of these <br />waters is leaching through soils, it is highly probable that C03- may precipi- <br />tate and remain in the soil while the more soluble salts leach back to the river <br />tributaries. Salt balance studies conducted by the Imperial Irrigation District <br />(1972) and Soil Conservation Service show that approximately 13% of the salts <br />brought into the valley precipitate as calcium carbonates and sulfates. No <br />problem is anticipated from the RSC of the projected waters since there will <br />be ample Ca++ to precipitate all the carbonate and still be some available in <br />solution. <br />Chloride Hazard <br />In Schofield's (1935) classification the projected waters would exceed <br />the moderate CI level at 1,300 TDS. His five levels were 4,7, 12,20 meq/I. <br />Fireman and Kraus (1965) divided their CI classification into four sections <br />separated at 2, 5, and 8 meq/I. The projected waters fall within the precau- <br />tionary zone. The California committee of consultants has adopted a 3 stage <br />division of Cl concentrations divided at 4 and 10 meq/I. All of the projected <br />values fall In the zone labeled increasing problems. Doneen's (1963) classifi.. <br />cation of potential salinity places all of the projected Colorado River water <br />within safe limits for good permeability, 5-20 meq/l, and medium permeability <br />3-15 meq/I. The CI value exceeds the critical value for low permeability soils <br />at 1,300 ppm TDS, i.e., 3-7 meq/l. The Israel salinity survey (1964) indicates <br />that there would be no danger of using this water for citrus on sandy and loamy <br />soils, but a medium risk in clay, the tolerance of citrus root stock being 10 <br />meq/I Cl-. It is believed that Cl may become a problem for semi-tolerant <br />plants in the Imperial clay. <br />Germination <br />The first time of contact between irrigation water and plants is during <br />the germination stage. At this time mteraction of humidity (see Hoffman and <br />Rawlins (1971)) can alter the salt tolerance of salt sensitive plants such as <br />onion. The more salt tolera~t crops such as cotton are not affected, Hoffman <br />and Phene (1971). <br />Magistad et al. (1943) found a significant difference In the tolerance <br /> <br />II <br />