Laserfiche WebLink
2.Review of a map provided by Colorado St ate University's IDS group. The map shows <br />the locations of the weather stations and the irrigated areas in the San Juan River basin. <br />3.Review of the USGS topographic maps. <br />It is recommended that if the elevation of the irrigate d area is different than the elevation of the weather <br />station, the temperatures used to calculate consum ptive use be adjusted using appropriate adiabatic <br />lapse rates. <br />3.0RESULTS AND CONCLUSIONS <br />The recommended changes for each hydrologic unit and county are summarized in Table 4 and <br />discussed in the following text. In hydrologic un its and counties where more than one weather station is <br />recommended, the weighting factor for each station was determined by the CSU IDS group using GIS <br />technology. <br />Hydrologic Unit 14080101, La Plata County <br />For this unit, the USBR recommended the Ignacio st ation. Based on topography it is recommended the <br />Vallecito Dam station should be used for the irrigated area on Los Pinos River upstream of its <br />confluence with Bear Creek. The continued use of the Ignacio station is recommended with some <br />reservation. Nolan J. Doesken indicated that th e data collection may be suspect. However, the <br />difference in monthly and annual precipitation betw een Ignacio and the closest weather stations, <br />Durango and Pagosa Springs, are significan t; therefore, their use is not recommended. <br />Hydrologic Unit 14080104, La Plata County <br />For this unit, the USBR recommended dropping the Ignacio station and using only Durango. This <br />change should not be made because: (1) the elev ation and topography of th e irrigated area south of <br />Durango is more similar to the area surrounding Ignacio, and (2) the average annual precipitation at <br />Durango is 19.3 inches as compared to 13.5 inches at Ignacio. The Durango station is recommended for <br />all irrigated areas which are north of Durango. These irrigated area are all located in HU 14080104N <br />on the IDS map showing the location of irrigated acres . Use of the Ignacio station is recommended for <br />irrigated areas which are south of Durango. These irrigated ar ea are all located in HU 14080104S on <br />the IDS map showing the location of irrigated acres. <br />Hydrologic Unit 14080105, La Plata County <br />For this unit, the USBR recommended dropping Cortez and using only the Fort Lewis station. The <br />USBR recommendation s hould be adopted. <br />Hydrologic Unit 14080107, Montezuma County <br />For this unit, the USBR recommended a change from th e Yellow Jacket station to the Cortez station. <br />This change should be adopted only for the irrigate d area tributary to the Navajo Wash. The remainder <br />of the irrigated area is located in the vicinity of Mancos. A precipitation station has been maintained at <br />Mancos since 1924, and since 1990, te mperature at Mancos has been recorded. Average annual <br />precipitation at Cortez and Mancos is 12.0 and 16.4 in ches, respectively, which is a difference of 4.4 <br />inches. It is recommended that the Mancos precipita tion be used for all irrigated areas not tributary to <br />2 <br />12.3.96 12.09-17 - Walter <br />