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75. Hea effluent electroconductivities of less than 2,250 micromhos/cm. should be cheived to minimize the potential of saline-soil development and resulting a erse effects on re vegetation of the down-gradient, heap rvn-on areas. Page 0 in Chapter 5, Quality of Irrigation Water in the 1954 U.S. Department of riculture's Diagnosis and Improvement of Saline and Alkali Soils states: "Nearly all rrigation waters that have been used successfully for a considerable time ve conductivity values less than 2,250 micromhs/cm. Waters of higher co uctivity are used occasionally, but crop production, except in unusual ci umstances, has not been satisfactory. Saline soils are ose in which the conductivity of the saturation extract is greater than millimhos/cm, (4,000 micromhos/cm.). It has been found that the conductivity of the satruation extract of a soil, in the absence of salt accumulat n from groundwater, usually ranges forrt 2 to 10 times as high as the concu tivity of the applied irrigation water. This increase in the salt concen ratios is the result of continual moisture extraction by plant roots an evaporation. Therefore, the use of waters of moderate to high salt content ay result in saline conditions, even where drainage is satisfactory. In general, waters with con ctivity values below 750 micromhos/cm. are satisfactory for irrigation insof as salt content is concerned, although salt sensitive crops may be advers y affected by the use of irrigation waters having conductivity values in the ra ge of 250 to 750 micromhos/crt~. Waters in the range from 750 to 2 250 micromhos/cm. are widely used and satisfactory crop growth is obtained un r good management and favorable drainage conditions, but saline conditio will develop if leaching and drainage are inadequate. Use of waters wi h conductivity ranges above 2,250 micromhos/cm. is the exception and very few instances can be titer where such waters have been used successfully. Only th more salt-tolerant crops can be grown with such waters but then only when the ater is used copioesly and the subsoil drainage is good." The U.S.D.A. Salinity Laboratory classi values of 750 to 2,250 micromhos/cm. as that: "High Salinity water (C3) cannot drainage. Even with adequate drainage, control may be required and plants with selected." Fies water with electroconductivity "High Sali 'ty Water (C3)", describing be used on s ils with restricted special manag ent for salinity good salt tole nce shoulc be The High Salinity water limitation was chosen as the heap ffluent. reclamation standard to be acheived as it is understood that direct pr ipitat.ion upon soils will dilute heap effluent runon and percolation, as w 1 as provide additional leaching of the affected soils. Additionally, hi er soil electroconductivity values in association with high sodium soi concentrations may help mitigate the soil-particle dispersion properties high odium concentration may impart to finer-textured soils.