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<br />t- <br />'1 <br />en <br />w <br /> <br />infiltrate instead of running off. The water percolates through the <br />unconfined spoils allowing greater opportunities for dissolving soluble <br />minerals through increases in both contact surfaces and residence time. The <br />water moves vertically until it encounters undisturbed bedrock where new <br />springs can be created. The usual result is an increase in the volume of <br />water because of reduced evapotranspiration and an increase in total dissolved <br />solids. <br /> <br />Studies[12,13,14] conducted on post-mining spoils in northwestern <br />Colorado indicate that the resulting TDS concentration of spoil derived <br />waters ranges from approximately 3,000 mg/L to 3,900 mg/L. The variability in <br />concentration is dependent upon water residence time and the chemical and <br />physical properties of the spoil. <br /> <br />Saline water is a byproduct of the production of oil and gas in the <br />Basin. It is not uncommon to produce several times the amount of saline <br />waters as oil. Approximately 25,000,000 barrels of saline waters were <br />produced during the December 1985 in Colorado from oil and gas operators. The <br />salinity of production waters varies greatly from location to location and is <br />dependent upon the producing formation. Common disposal techniques include <br />evaporation, injection, and discharge to local drainages. <br /> <br />The future development of the oil shale resources in Colorado, Utah, <br />and wyoming has the potential to increase salt loading to the Colorado River. <br />Salt increases can be attributed to the consumptive use of good quality water, <br />mine dewatering, and, if surface retorting is used, the leaching of spoil <br />materials similar to that of surface coal mining. <br /> <br />Some states have enacted drilling and ground water laws to protect <br />water quality. In the Colorado River Basin, ground water laws and strict <br />enforcement are essential to prevent further saline aqui~er movement and salt <br />loading. Many small saline ground water springs and/or flowing wells that <br />are probably linked to drilling activities have been identified in the Basin <br />and listed in previous progress reports. Seismograph drilling activities may <br />be particularly disruptive to shallow ground water systems, and stricter <br />regulation and enforcement should be considered. <br /> <br />The Meeker Dome salinity unit is one area where Reclamation has <br />plugged abandoned oil exploration drilling holes anticipating that the <br />aquifers are static and the saline water would not find another path back to <br />the surface. <br /> <br />6. Salinity Control Projects <br /> <br />The implementation of salinity control units prevented 126,800 tons <br />per year of salts from reaching the river in 1985. By 2010, salinity control <br />units will need to prevent slightly more than a million tons per year of salt <br />from entering the Colorado River. To achieve this goal, a mix of salinity <br />control methods are being investigated and constructed. Saline springs and <br />seeps may be collected for disposal by evaportation, industrial use, or deep <br />well injection. See Part VII, the Paradox Unit, for an example of a deep well <br />injection alternative. Other methods include both on and off farm delivery <br />system and irrigation improvements which reduce the loss of water and reduce <br />salt pickup by improving irrigation practices and by lining canals, laterals, <br />and ditches. See the Grand Valley Unit as an example of these kinds of <br />improvements. <br /> <br />V-6 <br />