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<br />Hydrology <br /> <br />QUALITY OF WATER <br /> <br />Quality of water analyses were made of the river flows at <br />various points within the project area. The results show that <br />the quality of the flows have been entirely satisfactory in the <br />upper reaches of the project. Upon entering the project area, <br />however, the salinity of the natural streamflow is increased by <br />return flows from the irrigated lands, No significant change <br />has been detected in the upper reaches of the project area, but <br />at the Hoehne diversion dam the salinity of the flow averages <br />approximately 1,000 micromhos, versus approximately 360 micromhos <br />for the unmixed water. During the winter months when the flows <br />at the Hoehne diversion are derived primarily from return flows, <br />the salinity .concentration increases to approximately 2,000 <br />micromhos. <br /> <br />Advancing further downstream, the salinity of the water <br />continues to increase. At the Burns and Duncan diversion the <br />electrical conductivity is nearly 3,000 micromhos during the <br />irrigation season and above 4,000 micromhosduring the winter.. <br />Irrigable lands totaling 861 acres which is 4,4 percent of the <br />irrigable area must depend on the return flows accruing during <br />the irrigation season for their principal water supply. <br />Leaching requirement studies 'using the quality of water available <br />during the irrigation season indicated that the. soil leaching <br />requirement is 25 percent. Experience over the past 100 years <br />'bears out that this re'luirement has been met by the unavoidable <br />farm losses. Since the project operations will not significantly <br />change the water quality, it is expected that the farm losses, <br />estimated at 30 percent, would continue to provide the necessary <br />soil leaching. <br /> <br /> <br /> <br />With respect to the use of the winter return flows, the <br />analyses indicated that the soil leaching requirement would be <br />greater than that provided by the unavoidable farm losses. <br />Therefore, their use for irrigation in the project area was <br />judged impractical and are not recommended, <br /> <br />DOWNSTREAM EFFECTS <br /> <br />The operation study recognizes the downstream water rights <br />of the Nine Mile and Highland Systems and shows bypasses to <br />satisfy these rights. The natural runoff from the basin below <br />Alfalfa was ignored in computing these bypasses; consequently, <br />the computed required bypass is high, Storage (except under <br />the Model decree) was limited to water which would otherwise <br /> <br />20 <br /> <br />Rev, 9/64 <br />