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<br />001714 <br /> <br />Long Hollow Dam and Reservoir Summary Report-Preliminary Draft <br /> <br />Creek gauges installed in 1988. Based on 85 years of record at the Hesperus gauge, the study <br />period was about 5 percent drier than average (see Table 4). The average La Plata River <br />discharge for the study period was 27,577 AF, which ranks at about the 45th percentile on a scale <br />from dry to wet. Flow data from the five stream gauges and diversion records for 18 irrigation <br />ditches were used to create the a daily model and develop a water balance for the La Plata River <br />and its tributaries. After calibrating the model with actual data, the model was used to simulate <br />stream conditions in Colorado during the study period with and without the proposed LHR. How <br />was ground water factored in?? <br /> <br />The model simulated the ability of the proposed LHR to fill in-priority. The model supplied <br />water to New Mexico in an amount equivalent to the historic administrative call from New <br />Mexico during the study period. For the study period, the average annual amount of water stored <br />in LHR was 3,540 AF. Figure 2 depicts the LHR end-of-month storage that is anticipated under <br />this operation plan. Based on historical Compact call conditions, LHR will fill 4 of 14 years with <br />an average fill of3,540 AF/yr. LHR will release all or nearly all stored water in 10 of 14 years. <br /> <br />The model also simulated the amount and timing of releases from LHR to deliver water to New <br />Mexico at the Colorado-New Mexico State Line gauge as required by the Compact while <br />allowing Colorado ditches on the La Plata River to divert in-priority by exchange without <br />impacting Compact deliveries. A 300-AF Compact Reserve Pool in LHR was used to deliver <br />water to New Mexico during the mid-summer low-flow period when the La Plata River often is <br />administered as a ~split river" (need to define or describe this condition here or during the <br />compact discussion) in Colorado. <br /> <br />The incremental diversions from this exchange program benefits the 18 ditches incorporated into <br />the water allocation model (see Table 5). LPWCD irrigators have expressed support for <br />allocation of exchange water by priority. <br /> <br />LPWCD will hire the necessary personnel to operate and maintain LHR (estimate costs ?). <br />Records will be kept of LHR inflow, outflow (bypass amounts plus releases from storage), and <br />remaining storage volumes for both the Compact Reserve Pool and the remaining storage. <br /> <br />991-077.115 <br />May 2004 <br /> <br />Wright Water Engineers, Inc. <br /> <br />Page 15 <br />