2025-09-26_REVISION - M2004025 (5)

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the lake bottom and sides are always saturated due to the level of alluvial water, no losses will occur due to infiltration. Losses will occur due to evaporation at the water surface. Based upon evaporation data for this location from the State Engineers office and precipitation data for this area,this pond will evaporate 42 inches or 3.5 acre-feet of water per acre of water surface. Since the existing pond of.57 acres will not be combined with the new pond from mining. Therefore, the area of new water surface is only 5.63 acres. This results in a consumptive use of 21.7 acre-feet annually. Since the site was previously used for alfalfa irrigated field,the consumptive use for this past irriga- tion is calculated at 1.72 acre-feet per acre per year of total effective precipitation and loss in the plants. This is a credit of 10.66 acre feet per year. Therefore the actual consumptive use after mining will be 21.7 ac ft/yr- 10.66 ac-ft/yr = 11.04 acre feet/yr. This will occur every year when the lake is in place. For the years of mining, a substitute water supply plan will be submitted to the Division of Water Resources for 1.54 acre feet per year. After mining,this amount will be changed to 11.04 acre feet per year. The augmentation plan after mining has been filed for the respective water rights with the water court. 5. Drainage Facilities The overall design of the sediment control system is to do the following: 1)contain the runoff from all disturbed areas for the 100 year- 24-hour storm. 2)keep undisturbed water from entering the site for all storms up to the 100 year 24-hour event. 3)It has been determined that pumping will not be required for this operation because the mining will occur in a manner that all water remains in the future lake area. A 2' topsoil berm is not used along the east side of the permit area to isolate water on and off the property as needed because water should not be an issue since the mine is not within a 100 year flood plain. The slopes of these berms will be 2H:1 V. The irrigation ditch south of Farnsworth Collection Ditch will prevent any water from the south entering the property. A small irrigation ditch east of the permit area also prevents any water from entering the site from this direction. Since the operation involves pure excavation of the resource,all water from the pit areas and facility areas will be detained within the 10 acre permit for the 100 year event,particularly since it is not in the 100 year flood plain. 19 North Fork Pit March 04