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Holcim South Platte Combined SWSP September 18, 2025 <br /> Plan IDs 3614, 4773, 3624, 4772, 4616, 3437, 3376, 3650, 3668, 5475, 5829, Ft 6243 Page 20 of <br /> 37 <br /> of Arvada, which will be released from the outfall of the Robert W. Hite Treatment Plant to <br /> the South Platte River at a rate not to exceed 2 acre-feet per day from July 1s' through <br /> September 305t <br /> Patterson Ditch <br /> Holcim has provided replacement water for the DPG Pit using the consumptive use <br /> associated with 8 out of 15 shares of the Delta Irrigation Company, the owner and operator <br /> of the Patterson Ditch, which were previously used for irrigation within the mining permit <br /> boundary. The fully consumable portion of the water associated with the shares will be <br /> delivered directly to the river for immediate credit, or delivered to a recharge pond for <br /> lagged recharge accretion credits, resulting from the delivery of water to the onsite <br /> recharge ponds under free river conditions with the knowledge and approval of the water <br /> commissioner. <br /> The Applicant submitted a historical consumptive use ("HCU") analysis with the 2021-2022 <br /> DPG Gravel Pit SWSP request, which was revised and updated in the 2022-2023 DPG Gravel <br /> Pit SWSP request. The analysis was performed for all 15 of the DPG Farms shares in the <br /> Patterson Ditch. The period of analysis selected was from 1990 through 2016. <br /> The DPG Farm is the last farm on the Patterson Ditch and all water returned to the ditch will <br /> flow back to the South Platte River via the Patterson Ditch wasteway located approximately <br /> 500 feet down-ditch. The HCU analysis performed for the use of the 15 shares on the DPG <br /> Farm indicated that the Patterson Ditch system was generally water-long. The 15 shares <br /> owned by DPG Farms yielded in excess of 6.5 acre-feet of water per irrigated acre. This <br /> "extra" water would have been available for other shareholders to divert, or would have <br /> been left in the ditch and turned back to the South Platte River at the end of the ditch <br /> wasteway. Due to this historical practice, a demand-based analysis was used to quantify <br /> historical consumptive use and historical return flow patterns for the shares. The modeled <br /> farm headgate delivery was determined as the lesser of the Patterson Ditch pro-rata farm <br /> headgate delivery and the calculated farm headgate delivery (calculated as the crop <br /> irrigation requirement divided by a 45 percent irrigation efficiency) for each month in the <br /> study period. <br /> The requested farm headgate delivery amount associated with the 8 shares in the Patterson <br /> Ditch for the period of May 1, 2025 through December 31, 2025 is 76 acre-feet with a <br /> consumptive use of 31.87 acre-feet and a return flow obligation of 44.13 acre-feet. The <br /> Applicant's deliveries under this SWSP are limited to the period of May through October. <br /> The historical return flow obligations associated with the 8 shares must be maintained under <br /> this SWSP. For the months of May through September, the daily return flow obligation will <br /> be determined by multiplying the applicable monthly return flow factor by the daily farm <br />