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<br />. <br /> <br />OGi~53 <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />.. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />based upon meteorological data would be better. With the data base available, it is <br />possible. There are approximately 33 weather stations in Colorado where pan evaporation <br />is measured or was measured historically. Nine of the sites are located in the Colorado <br />River basin. Wright, 1981, reported on the ratio of Class A pan evaporation to alfalfa Etr <br />(pan factor) over a 14-year period. The pan factor varied from about 1.05 to 1.4. If USBR <br />follows the recommendation above to develop a procedure to estimate reference crop <br />evapotranspiration throughout the basin, then the monthly pan factor could be easily <br />developed using the pan evaporation sites within the basin. <br /> <br />UDdate or Discontinue Use of Fullness Factor. The fullness factor as it is presently <br />utilized probably under-estimates reservoir evaporation in wet years and over-estimates <br />evaporation in dry years, particularly for reservoirs with junior water rights. The concept <br />has some utility where storage records are limited but data exists which can greatly <br />improve the accuracy of reservoir evaporation. <br /> <br />The COlorado Department of Natural Resources, State Engineers's Office <br />administers most if not all the reservoirs in the state. As a part of that administration, the <br />State Engineer records the contents of all reservoirs on a monthly basis. Area-capacity <br />curves are also available on many of the reservoirs that the ,State Engineer administers. <br />Using the data from the State Engineer, the USBR could use the actual average monthly <br />area to calculate reservoir evaporation. For those reservoirs which do not have area- <br />capacity curves, the USBR could develop monthly fullness factors based upon capacity. <br /> <br />EXPORTS <br /> <br />Exports are measured diversions out of the system. No changes are recommended. <br /> <br />MUNICIPAL AND INDUSTRIAL USES <br /> <br />The procedure used to determine the consumptive uses and losses attributable to <br />these uses was not reviewed. <br /> <br />17 <br /> <br />" ",,'-'\ " <br />\.)' , <br />