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Paradox Valley, lying along the axis of one of the largest anticlines, has been formed by the erosion of faulted and uplifted sandstone and shale formations, exposing a residual gypsum cap which covers about 15,000 feet of nearly pure salt and salt- rich shale. I I The geologic development of the valley is illustrated in the first two drawings. Briefly stated, the emergence of distant mountainous uplifts on each side of the area has placed intense lateral pressure on the intervening sedimentary formations, resulting in warping and fracturing along weak zones. ! I I I Under these pressures and the weight of the overlying formations, a deeply buried layer of salt (Paradox Member) from an ancient inland sea has flowed upward into the fractured area of the fold to create an elon- gated swell know as an anticline. As this has taken place, the Dolores River has remained in its original streambed and, in conjunction with weathering and erosion, has removed the upper materials to form the valley. These geologic processes are still active today in the valley. I II I I ~ Ground water comes into contact with the top of the salt formation, where it becomes nearly saturated, and surfaces as salt brine in the channel of the Dolores River near the middle of the valley (see Schematic Section along Paradox Valley) . , I The effect of the brine varies considerably, depending upon the amount of water in the river. High riverflows mix with and considerably dilute the brine; consequently, the salt content of the stream may in- crease from 250 milligrams per liter (mg/l) as it enters the valley to 450 mg/l as it exits the valley. I I With low riverflows, however, the salinity of the river in- creases from 1,000 mg/l to as high as 166,000 mg/l (approxi- mately five times as saline as sea water) as it crosses Paradox Valley. CONTROL MEASURES The Bureau .of Reclamation is studying possible methods of con- trolling the movement of brine ground water. The inflow of salt into the river could be substan- tially reduced by drilling a field of wells into the brine zone on both sides of the river and pumping saline ground water from the wells to lower the interface between the relatively fresh ground water and the underlying brine. This could require approximately ten wells, drilled to a depth of approximately 250 feet. Each well would be cased .and designed to pump approximately 225 gallons per minute of brine. The brine would be piped from the wells to a central collection point, where hydrogen sulfide gas would be converted to elemental sulfur and water in an oxidation process. This could require air stripping towers, pumps, chemical storage facilities, sand filters, and appurtenant facilities. The converted sulfur would then be piped to the evapora- tion pond with the brine. A buried pipeline of rein- forced plastic mortar would be required to carry the brine from the well field to Radium Evapora- tion. The pipeline would be about 20.3 miles long, extending to the southeast along State Highway 90, then crossing the divide between Paradox Valley and Dry Creek Basin and terminating at the pond. Eight relift pumping ...~ r f". rf' oJ ~,