2025-09-30_HYDROLOGY - M1977098 - Laserfiche WebLink

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Sievers Pit M-77-098 SWSP, Oldcastle SW Group, Inc. Page 4 of 13 September 30, 2025 The water rights used for augmentation of out-of-priority depletions from the operation are the Kaiser-Sievers Ditch, Priority No. 136 (WDID 3801147) and the Sievers Ranch Pond Nos. 1- 4 (WDIDs 3804001-3804004). Depletions in Excess of 83CW65 Augmentation Plan The anticipated consumptive use at the Sievers Pit mining operation under this SWSP is 31.07 acre-feet annually due to exposure of groundwater, surface water evaporation and washing, water lost with mined product, and dust control. Permit no. 77077-F was issued for this gravel pit, and allows 51 acre-feet of annual appropriation for: • 15.5 acre-feet of evaporative losses due to the exposure of 6 acres of groundwater (covered by the SWSP), • 15.0 acre-feet of water used for dust control (5.5 acre-feet covered by the SWSP and 9.5 acre-feet covered by case no. 83CW65), • 11.8 acre-feet of water lost with mined product (covered by the SWSP), • 3.6 acre-feet of water used for concrete production (covered by case no. 83CW65), and • 5.1 acre-feet of water used for asphalt production (covered by case no. 83CW65). Groundwater for domestic purposes to supply the office and shop on site is withdrawn from well permit no. 43047-F. This well is augmented by the West Divide Water Conservancy District ("WDWCD") under its augmentation plan decreed in Case No. 99CW320; therefore, out-of-priority depletions from the well are not covered by this SWSP. Groundwater and Surface Water Evaporation This SWSP anticipates that a maximum of 0.9 acres of water surface will be exposed at the site in the dewatering trench and ponds as shown on attached Figure 1. During the SWSP period, the total net evaporation loss annually from the 0.9 acres of exposed groundwater is estimated to be 2.32 acre-feet per year.