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FACTORS IN SAUNITY TRENDS 23 systems. These changes should result in reduced return flows and salt pickup. Projected water depletions through the 1965-80 period were largely unrealized; total depletions increased by approximately 12 percent. Previous Reclamation salinity projections have been too high, largely because the depletion projections were also too high. Transbasin diversions and increased reservoir evaporation account for most of the increased depletions from 1960-80; however, no additional salt pickup or loading occurred with these depletions. The large quantities of water expected to be depleted for steam power generation, coal gasification, oil shale, and mineral development have not been realized in the past decade. Even where new coal-fired powerplants have been constructed, some of the water has been obtained from existing agricultural rights. This conversion ofuse reduces the salt loading to the Colorado River by eliminating the pickup of salt by canal seepage and deep percolation. Reduced Flood Plains The reservoirs have also significantly reduced the peak flood flows downstream. The consequent reductions in the downstream 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. Energy Exploration and Development , Mar~y of the geologic formations 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 formations. Many 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). These aquifers are, therefore, static and often saline. Many static and saline aquifers are present in the Colorado River Basin. When a path of flow is provided by drilling or mining, these aquifers are mobilized, and brackish or saline waters flow back to the surface. The development of energy resources, specifically coal, oil and gas, and oil shale, in the Colorado River Basin may contribute significant quantities of salt to the Colorado River. Salinity can be increased either by dissolution of minerals or consumption of good quality water. The location offossil fuels are associated with marine derived formations. Any disturbance of these saline materials will increase the contact surfaces allowing for the dissolutions of previously unavailable soluble minerals. Salinity increases associated with the mining of coal can be attributed to leaching of coal spoil materials, discharge of saline ground waters, and increased sediment yields resulting from surface disturbing activities. Spoil materials have a greater permeability than undisturbed overburden, allowing most of the precipitation falling on the spoils to infiltrate instead of running off. The water percolates through the unconfined spoils allowing greater opportunities for dissolving soluble minerals through increases in both contact surfaces and residence time. The water moves vertically until it encounters undisturbed bedrock where new springs can be created. The usual result is an increase in the volume of water because of reduced evapotranspiration and an increase in total dissolved solids. Studies[12,13,14l conducted on postmining spoils in northwestern Colorado indicate that the resulting total dissolved solids (TDS) concentration of spoil derived waters ranges from approximately 3,000 mg/L to 3,900 mg/L. The variability in concentration depends on water residence time and the chemical and physical properties of the spoil. Saline water is a byproduct of the production of oil and gas in the basin. It is not uncommon to produce several times the amount of saline waters as oil. Oi~ and gas operators produced approximately 25,000,000 barrels of saline waters during December 1985 in Colorado. The