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<br />diversions and increased reservoir evaporation account for most of the <br />increased depletions from 1960-80; however, no additional salt pickup or <br />loading occurred with these depletions. <br />~ <br />~ The large quantities of water expected to be depleted for steam <br />OJ power generation, coal gasification, oil shale, and mineral development have <br />r'~ not been realized in the past decade. Even where new coal-fired powerplants <br />have been constructed, some of the water has been obtained from existing <br />agricultural rights. ~bile water uses have often changed, the total <br />depletions have increased only slightly. <br /> <br />In cases where powerplant water was obtained from existing <br />agricultural supplies, salt pickup may have been reduced since irrigated lands <br />in areas of coal deposits are often saline soils of Mancos Shale origin. <br /> <br />powerplants and new industries are no longer allowed to discharge <br />saline cooling tower blowdown waters back to the river. This total <br />containment policy resulted in some decreased salt loading during the 1970's. <br />Leakage from evaporation ponds and other disposal methods may eventually allow <br />some of these salts to reenter the river. <br /> <br />4. Reduced flood Plains <br /> <br />The reservoirs have also significantly reduced the peak flood flows <br />downstream. The consequent reductions in the downstream flood plains result <br />in decreased bank storage and possibly reduced salt flushing. At least <br />temporarily, the area between the old and new flood plains may act as a salt <br />sink, but the long-term salinity effects of the changes in the flood plains <br />are not known. <br /> <br />5. Energy Exploration and Development <br /> <br />Many of the geologic formations of the Colorado River Basin were <br />deposited in marine (salt water) or brackish water environments. Sulfates and <br />sodium chloride are prevalent salts in most of these formations. Many of the <br />sediments deposited in drier periods are capable of transmitting water, but <br />these aquifers are frequently sandwiched between hundreds or even thousands of <br />feet of impermeable shales (aquicludes). These aquifers are, therefore, <br />static and often saline. Many static and saline aquifers are present in the <br />Colorado River Basin. When a path of flow is provided by drilling or mining, <br />these aquifers are mobilized, and brackish or saline waters flow back to the <br />surface. <br /> <br />The development of energy resources, specifically coal, oil and gas, <br />and oil shale, in the colorado River Basin may contribute significant <br />quantities of salt to the Colorado River. Salinity can be increased either by <br />dissolution of minerals or consumption of good quality water. The location of <br />fossil fuels are associated with marine derived formations. Any disturbance <br />of the saline materials will increase the contact surfaces allowing for the <br />dissolutions of previously unavailable soluble minerals. <br /> <br />Salinity increases associated with the mining of coal can be <br />attributed to leaching of coal spoil materials, discharge of saline ground <br />waters, and increased sediment yields resulting from surface disturbing <br />activities. Spoil materials have a greater permeability than undisturbed <br />overburden, allowing most of the precipitation falling on the spoils to <br /> <br />~5 <br /> <br />- <br />