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Holcim South Platte Combined SWSP April 14, 2025 <br /> Plan IDs 3614, 4773, 3624, 4772, 4616, 3437, 3376, 3650, 3668, 5475, 5829, &t 6243 Page 15 of 37 <br /> wastewater treatment plant or the confluence of Spring Gulch and Saint Wain Creek. <br /> Deliveries will be made to St. Wain Creek during the period of April through October 2025 <br /> pursuant to the attached delivery schedule. <br /> Smith Et Emmons Ditch/Lighthouse Cove Pond Recharge <br /> Holcim owns 1.5 of 8 total outstanding shares in the Smith 6t Emmons Ditch Company. The <br /> 1.5 Smith 6t Emmons Ditch Company shares were historically used to irrigate 68 acres of <br /> pasture grass. The pro-rata diversions available at the farm headgate for the 1 .5 shares used <br /> on the property were estimated to total 224.21 acre-feet per year, based on the average <br /> headgate diversions for the Smith 6t Emmons Ditch (WDID 0600553) for the years 1950 to <br /> 1998, assuming a 10% ditch loss. Using a Modified Blaney-Criddle analysis the potential crop <br /> consumptive use for the 68 acres was determined to be 108.7 acre-feet. Assuming a farm <br /> efficiency of 55%, the average consumptive use was determined to be 91.65 acre-feet for <br /> the 1 .5 shares. Total return flow obligations from the use of the 1.5 shares were calculated <br /> as 132.56 acre-feet per year by subtracting the historical consumptive use from the pro-rata <br /> amount of diversions available at the farm headgate. One-half of the return flows (66.28 <br /> acre-feet) were assumed to occur as surface return flows and one-half of the return flows <br /> (66.28 acre-feet) were assumed to occur as subsurface return flows. The monthly and annual <br /> volumetric limits for the farm headgate deliveries are shown in the table below. <br /> Table E- Monthly and Annual Farm Headgate Delivery Limits (acre-feet) <br /> Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual <br /> 0 0 0.22 3.40 35.24 53.76 79.64 38.93 11 .86 1.15 0 0 224.21 <br /> Subsurface return flows were lagged to the river using the AWAS stream depletion model <br /> with the following parameters: <br /> • Distance from the centroid of the irrigated property to the river (X) = 800 ft <br /> • Alluvial aquifer width (W) = 9,300 ft <br /> • Specific yield (S) = 0.2 <br /> • Transmissivity (T) = 50,000 (gpd/ft) <br /> The resulting return flow factors are shown in Table F below. <br />