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<br />1 <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br /> <br />One of the primary resources that can be managed to allow better utilization of surface water <br /> <br /> <br />supplies are the underground aquifers in the San Luis Valley. By storage of surface water rights <br /> <br /> <br />in the aquifers, the aquifers can function as under ground water storage reservoirs. The filling of <br /> <br /> <br />the aquifers has historically occurred, but in an unplanned manner that has resulted in overfilling <br /> <br /> <br />in some areas and under-filling in other areas. One of the objectives of this project was to assist <br /> <br /> <br />in developing a better understanding of the dynamics of ground water recharge in the San Luis <br /> <br /> <br />Valley and to convey this information to water users and managers to facilitate maximum water <br /> <br /> <br />utilization and conservation. <br /> <br />Since elimination of the Rio Grande Compact debt, over delivery to the Compact has occurred in <br /> <br /> <br />several individual years. These over deliveries result in credits that may be used to reduce <br /> <br /> <br />Compact deliveries in subsequent years. However, the credits are subject to evaporation losses <br /> <br />in Elephant Butte Reservoir. It may be possible to reduce these over deliveries and efficiently <br /> <br /> <br />store more water in the aquifers ofthe San Luis Valley. This may be accomplished by means of <br /> <br /> <br />better managed irrigation season diversions and maximizing winter ground water recharge. In <br /> <br />many years the potential for Compact over deliveries do not become apparent until October or <br /> <br />November which is near the end of the accounting year for the Compact. It is also near the time <br /> <br />when ditches can be frozen shut by cold weather. During wet years and in the late fall or early <br /> <br /> <br />winter, the aquifers could be partially refilled, thereby supplying the ground water to be <br /> <br />withdrawn by wells during dry years. <br /> <br />Recharge of ground water has been difficult during November and December due to the forming <br /> <br /> <br />of ice in diversion structures and canal laterals. Additionally, changes in irrigation practices <br /> <br /> <br />from flood irrigation to significant numbers of center-pivot sprinkler systems that require less <br /> <br /> <br />volume of water has made it difficult for irrigators to use large wet year flows that can occur in <br /> <br /> <br />the spring. One of the objectives of this project was to construct a significant recharge structure <br /> <br /> <br />specifically designed to overcome much of the icing problems and provide additional capacity to <br /> <br />allow large diversions from the river during flood conditions. <br /> <br />1-2 <br />