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. PART VI EVALUATION OF EXISTING SALINITY CONDITIONS of the increased pickup or loading depletions from 1960-1980; however, occurred with these depletions. no add i tona 1 sal t . . ~ ' The large quantities of water steam power generation, coal gasification, opment have not been real ized in the past fired powerplants have been constructed I obtained from existing agricultural rights. changed, the total depletions have increased expected to be depleted for oil shale, and mineral devel- decade. Even Iohere new coal- some of the water has been t<.'hile water uses have often only slightly. ..~ (,Jl 1';" In cases loIhere polo'erplant water ....as obtained from existing agricultural supplies, salt pickup may have been reduced, Slnce irrigated lands in areas of coal deposits are often sal ine soils of !'lancos Shale orig in. POlo'erplants and new industries are no longer allo~d to dis- charge saline cooling tower blot.'Clown waters back to the rIver. This total containment policy resulted in some decreased salt loading during the 1970's. Leakagf' from evaporation ponds and other disposal methods may eventually allow some of these salts to reenter the river. 4. Reduced Flood Plains . The reservoirs have also significantly reduced the peak (flood) flows downstream (Figure IX-I). The consequent reductions in the down- stream flood plains result in decreased bank storage and possibly reduced salt flushing. At least temporarily the area between the old and new flood plains may act as a salt sink, but the long-term salinity effects of the changes in the flood plains are not known. 5. Potential New Sources of Salt Loading Many of the geolog ic format ions of the Colorado River Basin were deposited in marine (salt water) or brackish water environments. Sulfates and sodium chloride are prevalent salts in most of these forma- tions. :-iany of the sediments deposited in drier periods are capable of transmitting water, but these aquifers are frequently sandwiched between hundreds or even thousands of feet of impermeable shales (aquicludes). Therefore, these aquifers are static (no ground "''3ter movement) and often saline. ~any static and saline aquifers are present in the Colorado River Basin. Drilling and mining activities can disrupt aquicludes and mobilize these saline static aquifers. When a path of flow is provided by drilling or minin~, these aquifers are mobilized, and brackish or saline waters flow back to the surface. . Some states have enacted drilling and ground water laws to protect water quality. In the Colorado River Basin, ground water la...s and strict enforcement are essential to prevent further saline aquifer movement and salt loading. !1any small saline ground water springs and/or flowing wells that probably are linked to drilling activities have been ident i fied in the basin and listed In prev ious progress r€ports. 3D