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<br />. <br /> <br />. <br /> <br />. <br /> <br />l-& <br />..... <br />o <br />o <br /> <br />PART VIII. COLORADO RIVER SALINITY CONTROL PROGRAM <br /> <br />Section 206 of Title II of the Colorado River Basin Sslinity Control <br />Act, Public Law 93-320, of June 24, 1974, directs the Secretary of the <br />Interior, commencing on January I, 1975, and every 2 years thereafter, to <br />submit, simultaneously, to the President, the Congress, and the Advisory <br />Council, a report on the Colorado River Salinity Control Program covering <br />the progress of investigations, planning, and construction of salinity <br />control units for the 2 previous fiscal years. The report is to include <br />the effectiveness of the units, anticipated work to be accomplished to meet <br />the objectives of Title II with emphasis on the needs during the 5 years <br />immediately following the date of each report, and any special problems <br />that may be impeding progress in attaining an effective salinity control <br />program. Section 206 also provides that this report may be included in the <br />Quality of Water-Colorado River Basin biennial progress report. <br /> <br />A. Projects Authorized for Construction <br /> <br />Title II of Public Law 93-320 authorized the Secretary of the Interior <br />to construct as the initial stage of the Colorado River Water Quality <br />Improvement Program, the Paradox Valley Unit, Colorado; the Grand Valley <br />Unit, Colorado; the Crystal Geyser Unit, Utah; and the Las Vegas Wash Unit, <br />Nevada. The schedule of definite plan reports for projects authorized for <br />construction is shown on Figure 4. This section of the report presents a <br />brief description and summary of the status of investigations for each of <br />the projects authorized for construction. <br /> <br />1. Psradox Valley Unit <br /> <br />Paradox Valley, a collapsed salt anticline, is a northwest-southeast <br />trending valley 3 to 5 miles (5 to 8 km) wide located in southwestern <br />Colorado. It has an arid climate, dry and hot in the summer and dry and <br />cold in the winter. <br /> <br />Geologic investigations in the Colorado Plateau have established <br />the existence of a series of five major northwest-southeast trending salt <br />antic lines (e longated swells) about 100 milea (160 km) long. Paradox <br />Valley lies along the axis of one of these salt anticlines and was formed <br />from erosion of faulted and uplifted sandstone and shale formations <br />from above a residual gypsum cap overlying about 14,000 feet (4300 m) of <br />pure salt and salt-rich shale. The Dolores River remained in its ancient <br />streambed as the uplift and erosion of the valley developed. West Paradox <br />Creek heads in the La Sal Mountains and flows southeast through the north- <br />western half of Paradox Valley to the Dolores River. East Paradox Creek, <br />an intermittent stream, drains the southeastern half of Paradox Valley <br />before flowing into the Dolores River. <br /> <br />Previous estimates of the salinity contribution from the Paradox <br />Valley were based on spot measurements of flow and water quality of the <br />Dolores River as it enters and leaves the valley. Two stream gaging <br /> <br />64 <br />