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Ms.' Joanna Williams.. . RE: WW Farms Expansion SWSP Request Apri'I 22;' 2008 Page 2 of 5 We will use Table 1 to calculate evaporative losses for the. WW Farms Expansion Pit. When.'. groundwater: becomes exposed it will be in the°.form of.a dewatering trench that will probably be" aiound'`one acre in size, ' , The ,gross annual evaporation 'for, this. site was determined to, be 43-inches based :on the, NOAA Technical ReportNWS 33.: The average, annual precipitation was, determined to be 12 inches per year, based on,the precipitation isohyetals' from the.CDSS:. website for this area.. We obtained the data .from Western- Regional Climate Center for the Greeley UNC Weather station. This site had an average annual precipitation- total of 14 inches. We': took the monthly data :from the. Greeley UNC., site, and pro-rated each month to. ensure a 12 "inch annual total. We estimate that. 2.88- acre-feet of evaporation-will occur for each acre of exposure. Table 2 summarizes. total "depletions for -the WW Farms Expansion Pit, which includes both evaporative losses (shown in Table 1). and operational losses. Again this .site is not being. currently mined so there are.no depletions.as of yet, but when production starts it is estimated to be at 500,000 tons (14.7 acre-feet of water lost in, material) with :an.additional 2 acre-feet for dust control. Total operational losses are therefore estimated to be 16.7 acre-feet. The total depletions including one acre of evaporative loss will be 19.6 acre feet. WHITNEY DITCH CONSUMPTIVE USE ANALYSIS Aggregate recently acquired 2.5 shares of the Whitney. Ditch, (Stock Certificate No. 324), from Mr. -Ed Orr 'of, Greeley, Colorado. These shares have been used on the northwest '/4 of Section 30, Township 6 North, Range 66 West in Weld County, Colorado (see Figure 2). Mr. Orr has owned and operated the 24 acre farm irrigated with the 2.5 shares of the Whitney Ditch since September 2001. According to Mr. Orr, the land has been farmed for the past" 23 years. See Appendix:B for Mr. Orr's affidavit and Appendix C for the detailed historic consumptive use analysis. The most recent diversion records for the Whitney Ditch were taken from the Colorado Decision Support System network website. The average total annual diversions for the Whitney Ditch from .1950 to 2004 totaled 10,596 acre-feet. Mr. Orr's 2.5 shares of the 320 total outstanding shares equals a 0:78% pro-rata.portion of the Whitney Ditch diversions (2.5/320 = 0.78%). The average annual pro-rata diversions total 70.4 acre-feet. We assumed a 15% ditch" loss and that the flood irrigation was 60% efficient, therefore 42.2 acre feet of water was available to meet the crop requirements. These are the same factors that were decreed in TrollCo's 02CW390 Case and in the most recent application 08CW65 by Great Western Development Company. Using the State CU model, weather data available from the Greeley-UNC Weather Station (for the period from .1950-2004), and the. Upper. Plains Calibration Coefficients for, alfalfa and corn grain, we calculated a crop irrigation requirement (CIR) for the 24 acre farm (50% alfalfa and 50% corn grain) and determined it to be 43:8 acre- feet. The Upper Plains Calibrated Coefficient, is documented in SPDSS",(South Platte Decision Support System) Memorandum Final Task 59.1 dated March 18, 2005, updated • January 11, 2008 ' This memo. summarizes .the lysimeter:investigations that were used to 'develop the locally River Resource" Amendment to Permit M1999098 112C. Page G13 of G37