2025-09-10_HYDROLOGY - M1994005 - Laserfiche WebLink

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Colona Pit SWSP Page 3 of 13 September 10, 2025 attached to this letter. For the purposes of this SWSP, this affidavit will be accepted for dedication to this plan; however, if the State Engineer determines that a different affidavit or dedication process is necessary to ensure proper dedication of the shares, additional information may be required prior to future SWSP approvals. Depletions Evaporation Net evaporative depletions were calculated using a gross annual evaporation of 43.0 inches from the exposed water surface, with a credit of 9.6 inches for effective precipitation. Based on monthly average temperatures reported for the Montrose 2 and Ridgeway weather stations (1982-2006), ice cover was assumed for the months of December, January, and February; therefore, no evaporative consumptive use was charged for those months. For the purposes of this SWSP, the Applicant shall replace the net evaporative depletions from the exposed groundwater surface area that may occur during the assumed ice cover period (December through February) for any time that the pit is not completely covered by ice. The net depletion of groundwater due to evaporation from the 11.0 acres of exposed groundwater was calculated to be 28.1 acre-feet/year (2.6 acre-feet/acre/year), as shown on attached Table 1. At full buildout, the exposed groundwater surface is anticipated at 24.3 acres with an estimated annual evaporation of 62.1 acre-feet/year. Attached Tables 5 through 8 and Appendix C3 are the depletions and replacements anticipated at full buildout. Dust Suppression The Applicant has estimated that 5,400 gallons of water per day will be used for dust suppression, five (5) days per week for the period of March to November, or approximately 0.4 acre-foot/month. This results in a total of 3.3 acre-feet/year of water used for dust suppression, as shown on the attached Table 2.