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Augmentation <br />Augmentation for out of priority evaporative depletions and water lost from gravel <br />mining will be provided from phreatophyte and native vegetation credits and consumptive use <br />credits from acreage dried up under the Last Chance Ditch. <br />Phreatophyte Credits <br />Consumptive use credits aze being claimed for phreatophytes and native vegetation that <br />have been removed from the area that will be the exposed water surface of the Scott Pit. From a <br />pre-mining aerial photo of the Scott Pit and site studies, phreatophyte growth in the area consist <br />of dense to medium dense growth of Cottonwoods with an understory of Willows, Salt Cedar <br />(Tamarisk) and native grasses. <br />U.S.G.S. Professional Paper 600-D by Rantz was used as a reference to calculate <br />evapotranspiration by phreatophytes. The "Rantz Method" of calculating evapotranspiration of <br />phreatophytes is based on the SCS Blaney-Griddle method of determining crop consumption. A <br />crop coefficient or K value for crop growth was determined to be 1.28 for phreatophyte growth <br />in the floodplain where the water table is estimated to be 4.0 feet below the ground during the <br />growing season. Amedium-dense growth of phreatophytes was assumed, therefore, the K value <br />of 1.28 was adjusted to 1.09. A crop curve for fruit trees was used to estimate the monthly K <br />value and the DWR-TR-21 spreadsheet for user supplied K values was used to calculate <br />phreatophyte water consumption. Evapotranspiration for a phreatophyte mix of cottonwoods, <br />willows and salt cedars was calculated to be 47.41 inches per growth season with a total <br />consumption of 3.95 acre-feet per acre. Table 4 in Appendix B is a calculation of <br />evapotranspiration of phreatophytes. <br />It is estimated that 6.82 acres in Area 1 of the Scott Pit is attributed to phreatophyte <br />growth with annual water consumption of 26.94 acre-feet. All of Area 2, or 23.86 acres, is <br />attributed to phreatophyte growth with annual water consumption of 94.26 acre-feet, and 8.92 <br />acres of Area 3 is attributed to phreatophyte growth with annual water consumption of 35.23 <br />acre-feet. Total annual phreatophyte credits at mining completion is estimated to be 156.43 acre- <br />feet <br />Irrigation Credits <br />Out of priority evaporative depletions will also be augmented by irrigation credits from <br />21.0 acres of hay pasture that will be removed from irrigation in the Scott Pit mining boundaries. <br />The 21.0 acres have historically been irrigated by 42 shares (equivalent to 0.714 cfs) of the Last <br />Chance Ditch, owned and operated by the Loesch and Crann Ditch Company. <br />The Last Chance Ditch was decreed for 50.0 cfs on May 5, 1888 with an appropriation <br />date of March 23, 1887. Historical diversion records indicate that the average maximum <br />discharge over a 28 yeaz period was 42.8 cfs on June 18 with an average dischazge in June of <br />34.28 cfs. According to Phil Antes, the secretary for the Loesch &Crann Ditch Company, <br />there are currently 2,817 outstanding shazes in the Loesch &Crann Ditch Company with an <br />3 <br />