Laserfiche WebLink
<br />1932 <br /> <br />. <br /> <br />orado for use on the more populated, water-short eastern slope. The Project began importing water in 1972. <br /> <br />From 1972-94, the Project imported an annual median volume of about 47,300 acre-ft!yr into the Arkansas River <br /> <br />Basin. During the summer months, the Project diverts water from the western slope to the eastern slope. where it <br /> <br />is held in storage until municipal or irrigation water-supply demands must be satisfied. Imported water may be <br /> <br />stored in the upper basin or in Pueblo Reservoir, the farthest downstream facility of the Project. Imported water <br /> <br />is generally stored in the upper basin as long as possible to minimize evaporative losses, which are higher in Pueblo <br /> <br />Reservoir than in the upper basin. <br /> <br />Storage began in Pueblo Reservoir in 1974 and the dam was completed in 1975. The reservoir had an initial <br /> <br />storage capacity of 357,678 acre-fl. Since water was first impounded in Pueblo Reservoir, reservoir storage has <br /> <br />varied greatly because of variations in the inflow and in the demand for stored water. The majority of the storage <br /> <br />space in Pueblo Reservoir is reserved for Project water. although storage of some non-Project water is granted <br /> <br />under a limited number ofsrorage contracts. The majoriry of the annual inflow to the reservoir typically occurs <br /> <br />. during May through July. Reservoir storage generally decreases substantially by the end of the growing season <br /> <br />because of decreased inflow and large downstream demands for irrigation water. <br /> <br />The most notable aspect of the operation of Pueblo Reservoir, in tenns of its effect on the historic stream- <br /> <br />flow regime of the lower Arkansas River. is the Winter Water Storage Program (WWSP). In the winter months <br /> <br />(November-March), prior to the implementation of the WWSP in \975, irrigators in the lower Arkansas River <br /> <br />valley would typically divert their appropriated Arkansas Ri\'er water onto fallow fields to maintain soil moisture. <br /> <br />It was recognized that a more beneficial use of this water would be to store it during the winter and then release <br /> <br />the water to the river for the downstream irrigators to use during times when discharge was too low to meet irriga- <br /> <br />tion needs. Under Colorado water law, it is not permissible to store water that is diverted with direct-flow water <br /> <br />rights. Therefore, the WWSP was created to allow several irrigation canal companies downstream from Pueblo <br /> <br />Reservoir to store their direct-flow water in Pueblo Reservoir and several private off-channel reservoirs during <br /> <br />the winter months, and to use this water during the crop-growing season. Winter-water storage is allowed from <br /> <br />. November 15 to March 15. Generally, WWSP water is released from storage at times when discharge is not large <br /> <br />12 <br />