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<br />1 0- f) <br />~.;. <br /> <br />C4 _ VERY HIGH SALINITY WATER is not suitable for irrigation under ordinary <br />conditions, but may be used occasionally under special circumstances of <br />permeable ,soil, adequate drainage, excess irrigation water applied to <br />provide considerable leaching and very salt tolerant crops. <br /> <br />Sodium Classification <br /> <br />Sl - LOW SODIUM WATER can be used on almost all soils, with little danger of <br />the development of a sodium problem. However, sodium sensitive crops may <br />accumulate injurious amounts of sodium in the leaves. <br /> <br />S2 _ MEDIUM SODIUM WATER may present a moderate sodium problem in fine-textured <br />(clays) soils unless there is gypsum in the soil. This water can be used <br />on coarse-textured (sandy) or organic soils that take water well. <br /> <br />S3 _ HIGH SODIUM WATER may produce problems in soils that do not contain gypsum <br />and will require special management - good drainage, high leaching and <br />additions of organic matter. <br /> <br />S4 _ VERY HIGH SODIUM WATER is generally unsatisfactory for irrigation except <br />at low or medium salinity levels where the use of gypsum or some other <br />amendment makes it possible. <br /> <br />To evaluate the quality of a water sample, first consideration should <br />be given to the salinity and sodium hazards. Consideration should then be given <br />to bicarbonate and boron. Finally, recommendations for use of the water must <br />take into account such factors as the permeability of the soil, drainage, quan- <br />tity of water used and type of crops grown. <br /> <br />As shown in Tables 4A - 4D, two of the samples have hazards of C3-Sl <br />and two have hazards of C4-S2. Three of the samples have minimum RSe, but one <br />sample, a C3-S1 hazard, has RSC in the marginal range. The boron concentrations <br />of all four samples are small enough not to be a consideration in the evaluation. <br /> <br />If the two wells with the C4-S2 ratings were the only source or the <br />primary source of irrigation water, it is doubtful they could be used without <br />damage to crops and soil. The other two probably could be used without incur- <br />ring damage becau'se of permeable soil and adequate drainage, even though one <br />has,a marginal value of RSC. <br /> <br />The leaching of the soil with large surface diversions, the permeabil- <br />ity of the soil and the good drainage of the valley-fill aquifer compensate the <br />hazards involved with the use of these supplies to supplement surface diversions. <br />If this were not so a problem would have developed from historic use. <br /> <br />- 12 - <br />