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<br />.' <br /> <br />. <br /> <br />NUCLA IRRIGATION REPORT <br /> <br />General <br /> <br />The Town of Nucla, Colorado is 10cated in western Colorado at the south- <br />western edge of the Uncompahgre Plateau. The elevation is approximately <br />5;850 feet. Historically the town has received approximately 11.94 inches <br />of precipitation annually. Only.partial weather records have been kept <br />by the Bureau of Land Management (B.L.M.) to determine the range fire <br />hazard. These records are unpublished. In determining the irrigation <br />requirements, the published, 10ng-term records of Uravan, Colorado and <br />Norwood, Colorado were used, and compared to the records of the B.L.M. <br /> <br />Annual Water Requirement <br /> <br />The Blaney-Criddle method for determining the consumptive use of plants <br />was employed to determine the irrigation requirement for the average <br />residence. The lie thod is based on the average !lX)nthly temperature and <br />the percentage of daylight hours. After determining the total moisture <br />required by the plants, the natural precipitation is deducted from the <br />total requirement and the remainder becomes the amount to be applied by <br />irriga tion. <br /> <br />. <br /> <br />From the extended weather record it was determined that the average date <br />of the last killing frost in the spring is April 14th and the first killing <br />frost in the fall is October 7th, giving a frost-free period of 161 days. <br />However, it has been determined that grass requires water prior to the last <br />killing frost and after the first kil1ing frost, therefore, a period from <br />April 1st to October 31st was selected for determining the consumptive use, <br />The consumptive use was determined to be 33.51 inches per year as shown in <br />Table 1 and the irrigation application rate was 33.23 inches per year. <br /> <br /> TABLE 1 <br /> IRRIGATION REQUIREMENT (in ches ) <br /> Consump. Irrig. Eff.* Application <br />Month Use Precip. Rqmt. Correct. Rate <br />Apr il 4.13 in. 0.94 in. 3.19 in. 0.96 in. 4.15 in. <br />May 4.50 0.60 3.90 1. 17 5.07 <br />June 5.65 0.64 5.01 1. 50 6.51 <br />July 5.95 1. 47 4.48 1. 34 5.82 <br />Augus t 5.43 1. 26 4.17 1. 25 5.42 <br />September 4.34 1. 42 2.92 0.88 3.80 <br />October 3.51 1. 62 1. 89 0.57 2.46 <br />Total 33.51 in. 7.95 in. 25.56 in. 7.67 in. 33.23 in. <br />*Add 30% for application 10sses. <br /> <br />Assuming an irrigated area of 7,500 sq. ft. per residences the annual water <br />requirement becolles 155,350 gallons per residence as shown in Table 2. <br /> <br />. <br /> <br />10 <br />