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Hydrologic Unit 14030002, Montezuma County <br />For this unit, the USBR recommended changing from th e Dolores station to the Cortez. One reason is <br />the lack of data; only precipitation data is availa ble at the Dolores station. However, based upon an <br />analysis of precipitation, topography, and the locati on of irrigated lands, it is recommended that three <br />weather stations be used in this unit. The Rico station should be used for estimating crop consumptive <br />use for irrigated areas upstream of the Dolores River and West Dolores confluence. The topography <br />surrounding Rico is similar to that surrounding irrigate d lands in this area. It is noted that elevation <br />corrections may need to be applied to the temperatures. <br />For areas downstream of the Dolores River and West Dolores confluence, a com bination of two stations <br />should be used. The precipitation at Dolores and temp erature data at Cortez can be utilized to estimate <br />crop consumptive use of these irrigated lands. <br />Hydrologic Unit 14030002, San Miguel County <br />For this unit, the CULR used the Paradox station. It is important to note that the Paradox 1E station was <br />moved to the Paradox 1W site in 1977. No data was lost; the last day of data for Paradox 1E was <br />October 31, 1977, and the first day of data for Paradox 1W was November 1, 1977. However, in <br />moving the station, the elevation was reduced by 250 feet. A combination of the data from both sites <br />was used in this analysis. Two additional stati ons, Norwood and Northdale were considered for this <br />unit. Temperature differences between Paradox, Norwood and Northdale are about what one would <br />expect given the elevation differen ces between the stations. Paradox is not a representative temperature <br />station as it is located in a large valley with mount ains to the north, west, and east. Average annual <br />precipitation at the three stations is: Para dox (13.89 inches), Norwood (14.83 inches) and Northdale <br />(11.86 inches). Based upon the location of the irrigate d area with respect to th e weather stations and <br />topography, the Northdale station is recommended for this hydrologic unit. <br />Hydrologic Unit 14030003, Montrose County <br />The USBR's use of the Norwood and Uravan stations is acceptable; however, review of the map of <br />irrigated areas found that the irri gated area should not be split 50-50 between the two stations. The <br />Norwood station should be used for estimating crop cons umptive use for irrigated areas upstream of the <br />San Miguel and Naturita Creek confluence. The Uravan station is recommended for estimating crop <br />consumptive use for irrigated areas downstream of the San Miguel and Naturita Creek confluence. <br />Hydrologic Unit 14030003, San Miguel <br />For this unit, the CULR used the Norwood station. This choice is applicable to most of the unit. <br />However, the topography in the higher elevations is rugged. Most of th e irrigated lands upstream of the <br />San Miguel and Beaver Creek confluence are located in steep river valleys. Four stations are located <br />upstream of this confluence: Placerville, Telluride , Ames, and Trout Lake. Only Telluride records <br />temperature and precipitation th roughout the 1970-90 period; Placerv ille records only precipitation <br />throughout the 1970-90 period. The difference in average annual precipitation at Telluride (23.51 <br />inches) and at Placerville (19.55 inches) may be due to local orographic effects. It is recommended that <br />temperature data from Telluride and precipitation data from Placerville be used for irrigated areas <br />upstream of the San Miguel and Beaver Creek conf luence. For areas downstream of the San Miguel <br />and Beaver Creek confluence, Norwood may be used. <br />Hydrologic Unit 14030004, Montrose County <br />3 <br />12..3.96 12.09-16 - Walter <br />