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o o c-_~ (..-, ~ CO ~a. tt~a~"oo San Juan River Basin Hydrology Model New Mexico Non-Irrigation Depletions Comparison of Depletions Used in the Natural Flow Study vs Depletions from the Colorado River System Consumptive Uses & Losses Reports. Intra The San Juan River Basin Hydrology Model uses resulls of Ihe Natural Ftow Study(NF) as it's basic hydrology data set. The NF based much 01 its New Mexico non-irrigation depletions on 'Northwest Unit, New MexIco Regional Waler Resources Assessments, Technical Memorandum," USBR in cooperation with NM Interstate Stream Commission, December 1994. John Whipple, NMISC, has recommended that NM non-irrigation depletions use resulls 01 the CU&L Reports. ThiS report compares these two sets 01 depletions. List of Sheets Summary Data - Annual Depletions by Category Table I . CU&L Table 2 - NF Table 3 - NF minus CU&L Table 4 - (NF minus CU&L) I NF . 100.0 Charts Figure 1 - Total Depletion, Irrigalion Depletion and Non-Irrigaton Depletion Figure 2 - Reservoir Evaporation Livestock & Stock Pond Evaporation Urban and Rural Thermal Mineral F&W Results The average annual non-irrigation depletions compare closely. The NF value 01 70,463 al and the CU&L value of 75,900 af diller by about 8%. The annual values show wider descrepency. The max positive difference occurs in 1976, where the NF value of 60,765al is about 12% greater than the CU&L value of 53,400 af. The maximum negative difference occurs in 1989, with a NF value 01 87,212af and a CU&L value 01116,200 af, a difference of about -33%. Figure 1 compares the annual values and shows that NF are the same or greater than CU&L values for Ihe first ten years, but then the CU&L values are generaily greater than the NF values for the remaining twelve years. Annual depletions by the six categories shown in Figure 2. We are using the same data for Thermal Power Depletions, but 1991 and 1992 were estimated based on preliminary data and need to be adjusted, Navajo Reservoir Evaporalion is a major depletion that requires checking on the history of Area-Capacity-Elevation tables and using pan evaporation data instead of standard monthly rates. The other four categories each has it's problems, mainly associtaled with how minor reservoir evaporation was reported in the past. Minerat, Livestock and Stockpond Evaporalion, and Fish and Wildlife display drastic dillerences for the two sets of data. ~I"e.e.._ Ik~/or --/~/~.