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<br />Irrigated pasture and alfalfa will typically have an irrigation application efficiency of 50% <br />on land that has been leveled. To verify this assumption, a consumptive use analysis was <br />performed for the entire ranch and compared to Water Commissioner diversion records. Part of <br />the lands irrigated on the ranch receive a commingled supply of both Fish Ditch and Rio Grande <br />Canal water. Based on the location of this land and proximity to the ditches, it was assumed that <br />the land served by both surface water supplies received one-quarter of its supply from Fish Ditch <br />and three-quarters of its supply from Rio Grande Canal. From Table 5, it is estimated that <br />historically the Fish Ditch has irrigated 632 acres (356.22 + 1/4 * 1104.51) on which on average <br />826 acre-ft/yr have been consumed (514.24 + ]/4 * 1247.17). From diversion records <br />summarized in Table 4, on average 1,612 acre-ft/yr of water has been supplied to the ranch. <br />Consequently, an application efficiency of 50% is reasonable (826 ! 1612 = 51.2%). <br />It is estimated that Rio Grande Canal has historically imgated 1,277 acres (448.27 + 3/4 <br />1104.51). Surface water irrigation of this land has been augmented late season by ground water. <br />There are four wells on this property, including: Case W 195 Well ]adjudicated for 1050 gpm, - <br />Case ~V195 Well 2 adjudicated for 600 gpm, Case W 195 Well 3 adjudicated for 1400 gpm, and <br />Case W 195 Well 4 adjudicated for 1400 gpm. It is assumed that each of these wells is used for <br />70 days each year and flow at their decreed capacity. Consequently, it is estimated that ground <br />water supplies contribute 1,377 acre-ft per year. The average annual consumptive use on the Rio <br />Grande Canal lands has been 1602 acre-ft/yr (666.74 + 3/4 * 1247.17). This consumptive use has <br />been supported by 2,791 acre-ft/yr of diversions (1414 + 1377). Consequently, an application <br />efficiency of 50% is reasonable (1602 / 2791 = 57.4%). <br />To offset out-of-priority depletions caused by surface evaporation and the mining <br />operation, land that has historically been irrigated will be dried up. To accommodate the gravel <br />mining operation, Parcels 1, 2, and 3 in Section 12 shall be dried up. These three parcels have a <br />total consumptive use credit of 233.84 acre-ft per year (62.13 + 68.90 + 102.81) Assuming that <br />75,000 tons of gravel are extracted each year, this dry up will offset surface evaporation and <br />gravel washing requirements for the first 25 years until the ponded area is 47 acres. <br />~3 66 acre- ft / yr per acre of pit s 47 acres <br />+~2 94.x10 'acre- ft per ton of gravel extracted ~ 75,000 tons gavel ! yr.r 2~ yrs~ <br />= 327 acre - ft <br />where Pit Surface Area = 1.875 acre - ft / yr x 25 yrs <br />As more material is mined and the pit is enlarged, additional parcels shall be dried up. <br />Once minin~~ is complete and the gravel pits have created 100 acres of ponds, enough acreage will <br />be dried up to free up 366 acre-ft/yr of consumptive use credit. This will be accomplished by <br />drying up parcels I through 6 and 33.9 acres of parcel 7. <br />62.12+68.9+103.81+25.44+46.92+9.09+33 9x 1.5~ = 366 acre - ft / yr <br />12 <br />