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Shores Substitute Water Supply Plan <br /> December 18, 2019 <br /> Page 4 of 7 <br /> According to the Applicant, the 1.3 shares were historically used to irrigate the North Farm <br /> ("Farm"), located in the E1/2 of the NW1/4, Section 1, Township 2 North, Range 68 West of the 6tn <br /> P.M. in Weld County, as shown on attached Figures 1 and 3. <br /> The Applicant submitted a historical consumptive use ("HCU") analysis with the SWSP request. <br /> The period of analysis selected is 1967 through 1996. Starting in 1997 development began on the <br /> property, including construction of a gravel mine. For this period, diversion records for the Rural <br /> Ditch were downloaded from Hydrobase. Daily diversions for the Rural Ditch were adjusted to <br /> include only the diversion up to 83 cfs (the maximum decreed diversion rate of the Rural Ditch <br /> water rights). <br /> The HCU analysis conducted for the Farm relied on the following method and assumptions: <br /> • Modeled using the Modified Blaney-Criddle method with TR-21 crop coefficients. <br /> • The diversion records were limited to the period of proposed April 1 through October 31. <br /> • The Soil Conservation Service methodology was used to calculate effective precipitation. <br /> • Assumed ditch loss of 15 percent. <br /> • Temperature and precipitation data from the NOAA Longmont 2 ESE weather station (ID: <br /> U SC00055116) was used. <br /> • The Farm was flood irrigated. The Applicant proposed maximum irrigation efficiencies of <br /> 55 percent. <br /> • Historical irrigated acreage was developed from review of an aerial photograph from 1986. <br /> • Cropping was corn silage, sugar beets and pasture grass, as shown in the crop distribution <br /> table in the SWSP request. <br /> The HCU results are summarized in attached Table 2. <br /> Deliveries are limited to April through October and are limited to the historical monthly average <br /> farm headgate delivery as summarized in Table 3 Below: <br /> Table 3- Volumetric Delivery Limits - Subject Shares (ac-ft) <br /> Apr May Jun Jul Aug Sep Oct <br /> 0.56 14.05 26.07 43.39 29.74 10.62 1.08 <br /> Return Flow Obligations of Ditch Rights <br /> The lagged return flows were calculated using the Glover alluvial aquifer method as contained in <br /> the Alluvial Water Accounting System ("AWAS") model developed by the Integrated Decision <br /> Support Group at Colorado State University. <br /> Return flows were split 40 percent surface runoff and 60 percent deep percolation. The aquifer <br /> parameters used to lag the deep percolation return flows are shown in Table 4. <br /> Table 4- Glover aquifer parameters for deep percolation return flows <br /> Operations X W T Sy <br /> Deep percolation return flows 21520 10,000 73,200 0.2 <br />