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Steamboat Sand and Gravel Pit SWSP Page 3 of 8 <br />March 21, 2014 <br />basin's generalized transmissivity value determined in the June 2004 Yampa River Basin Water <br />Resource Planning Model prepared by Boyle Engineering Corporation), specific yield (SY) = 0.13 <br />(based on the Yampa River Basin Water Resource Planning Model), the distance X (from the <br />stream to the centroid of the dewatering trench) = 2,120 feet, and the location of the parallel <br />impermeable boundary W, estimated to be 3,500 feet from the stream (adopted from the Yampa <br />River Basin Water Resource Planning Model). <br />The total lagged depletions from evaporation and operational uses are anticipated to equal <br />6.52 acre -feet for the period of February 1, 2014 through January 31, 2015. <br />Replacements <br />The sources of replacement water to be used for this SWSP are consumptive use credits <br />associated with the historical irrigation use of 1.38 cfs in the Suttle Ditch water rights and 1.0 cfs in <br />the Weiskopf Ditch water rights. <br />The water rights in the Suttle Ditch and the Weiskopf Ditch are owned by the property <br />owners of the Steamboat Sand and Gravel Pit and the adjacent Four Sisters Pit; and these owners <br />have authorized Alpine to utilize these water rights as replacement sources in the SWSP. The 1.38 <br />cfs in the Suttle Ditch was historically used to irrigate the lands within the nearby Four Sisters Pit <br />and the 1.0 cfs in the Weiskopf Ditch was historically used to irrigate the lands within the <br />Steamboat Sand and Gravel Pit. <br />For the requested SWSP period, Alpine will make replacement for out of priority depletions <br />affecting the Yampa River during the historical call period from April 15 through August 15 of each <br />year, using 35.40 acre -feet of historical net stream depletions during April through August from the <br />dry-up of 39.9 acres of historically irrigated lands within the Four Sisters Pit with 1.38 cfs by the <br />Suttle Ditch as shown on the attached Table 7. Alpine does not propose to use any dry -up <br />consumptive use credits under the Weiskopf Ditch during the requested SWSP period, but may <br />propose to utilize dry -up consumptive use credits in future SWSPs. <br />In order to determine how much credit is available from the dry-up of the historically <br />irrigated lands under the Suttle Ditch, you are proposing to use the quantification provided in the <br />decree in Case No. 2008CW94, since the 39.9 acres of historically irrigated lands within the Four <br />Sisters Pit are adjacent to the historically irrigated lands identified in the decree in Case No. <br />2008CW94. The historical consumptive use analysis for the Suttle Ditch in Case No. 2008CW94 <br />produced a dry-up credit of 1.09 acre -feet per acre for the period of 1977 through 2007. The crop <br />irrigated was entirely pasture grass. The consumptive use credit was calculated using the Modified <br />Blaney - Criddle Method outlined in SCS TR -21, with daily temperature and precipitation data from <br />the nearby Steamboat Springs weather station. Altitude adjustment for pasture grass was applied <br />in accordance with ASCE Manual and Report No. 70. The ditch loss for the Suttle Ditch was <br />assumed to be 10% and the maximum irrigation efficiency was assumed 50% reflecting the flood <br />irrigation practices historically used in this area. Thus, the consumptive use credit associated with <br />the 1.38 cfs in the Suttle Ditch is 43.37 acre -feet per year (1.09x39.9= 43.37) for the period of April <br />