2015-03-20_HYDROLOGY - M2001090 - Laserfiche WebLink

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t Steamboat Sand and Gravel Pit SWSP Page 3 of 8 March 11, 2015 Planning Model), the distance X (from the stream to the centroid of the dewatering trench) = 2,120 feet, and the location of the parallel impermeable boundary W, estimated to be 3,500 feet from the stream (adopted from the Yampa River Basin Water Resource Planning Model). The total lagged depletions from evaporation and operational uses are anticipated to equal 6.85 acre -feet for the period of February 1, 2015 through January 31, 2016. Replacements The sources of replacement water to be used for this SWSP are consumptive use credits associated with the historical irrigation use of 1.38 cfs in the Suttle Ditch water rights and 1.0 cfs in the Weiskopf Ditch water rights. The water rights in the Suttle Ditch and the Weiskopf Ditch are owned by the property owners of the Steamboat Sand and Gravel Pit and the adjacent Four Sisters Pit; and these owners have authorized Alpine to utilize these water rights as replacement sources in the SWSP. The 1.38 cfs in the Suttle Ditch was historically used to irrigate the lands within the nearby Four Sisters Pit and the 1.0 cfs in the Weiskopf Ditch was historically used to irrigate the lands within the Steamboat Sand and Gravel Pit. For the requested SWSP period, Alpine will make replacement for out of priority depletions affecting the Yampa River during the historical call period from April 15 through August 15 of each year, using 35.40 acre -feet of historical net stream depletions during April through August from the dry-up of 39.9 acres of historically irrigated lands within the Four Sisters Pit with 1.38 cfs by the Suttle Ditch as shown on the attached Table 7. Alpine does not propose to use any dry-up consumptive use credits under the Weiskopf Ditch during the requested SWSP period, but may propose to utilize dry-up consumptive use credits in future SWSPs. In order to determine how much credit is available from the dry-up of the historically irrigated lands under the Suttle Ditch, you are proposing to use the quantification provided in the decree in Case No. 2008CW94, since the 39.9 acres of historically irrigated lands within the Four Sisters Pit are adjacent to the historically irrigated lands identified in the decree in Case No. 2008CW94. The historical consumptive use analysis for the Suttle Ditch in Case No. 2008CW94 produced a dry-up credit of 1.09 acre -feet per acre for the period of 1977 through 2007. The crop irrigated was entirely pasture grass. The consumptive use credit was calculated using the Modified Blaney - Criddle Method outlined in SCS TR -21, with daily temperature and precipitation data from the nearby Steamboat Springs weather station. Altitude adjustment for pasture grass was applied in accordance with ASCE Manual and Report No. 70. The ditch loss for the Suttle Ditch was assumed to be 10% and the maximum irrigation efficiency was assumed 50% reflecting the flood irrigation practices historically used in this area. Thus, the consumptive use credit associated with 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 through October based on the quantification provided in the decree in Case No. 2008CW94 and is presented in the attached Table 5. In order to determine how much credit is available from the dry-up of the lands historically irrigated by the Weiskopf Ditch, a ditch -wide historical consumptive use analysis was performed for the period of 1950 through 2005, which was considered to be representative as it includes wet, dry and average years. The annual irrigated acreage during the study period 'arCO�o�. 1313 Sherman Street, Room 821, Denver, CO 80203 P 303.866.3581 F 303.866.2223 www.water.state.co.us