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approximately 50 inches according to NOAA Technical Report NWS 33, Evaporation Atlas <br /> for the Contiguous 48 United States. The nearest weather station is the National Weather <br /> Service (NWS) located in the Pueblo Airpark approximately 1.7 miles northwest of the site. <br /> The average annual precipitation is 12.02 inches. Effective precipitation, that part of <br /> historical precipitation which was consumed by native vegetation on land to be covered by <br /> water surface, is conservatively estimated to be 70 percent of the total precipitation. The <br /> annual average effective precipitation at the property is estimated to be 8.41 inches. When <br /> subtracting the effective precipitation from the gross evaporation yields, the net annual <br /> evaporation is 41.59 inches, or 3.47 acre-feet per acre. The Fresh Water Pond is <br /> approximately 2 acres and the Siltation Ponds will be approximately 4 acres. The <br /> approximate acreage of open water surface is 6.6 acres. The annual amount of evaporation <br /> from open water surfaces is approximately 22.9 acre-feet. <br /> Mining Production &Operations: The Operator expects to extract approximately 500,000 <br /> tons annually of aggregate material from the site. All water retained in the recovered <br /> material will be replaced pursuant to the Substitute Water Supply Plan (SWSP). The total <br /> annual amount of water retained in the gravel product from mining activities totals <br /> approximately 6.8 acre-feet. The SWSP is renewed annually and will reflect analysis of <br /> production and depletion anticipated in each year of operation. <br /> In addition, an estimated 3.3 acre-feet of water per year will be used for dust control based <br /> (approximately) on 5,000 gallons per day for 5 days a week for 10 months. <br /> Annually the total evaporative and operational losses from mining activities (open water <br /> surface evaporation, water retained in the aggregate product, dust suppression)totals 33.0 <br /> acre-feet of depletion which must be augmented. All depletions will be lagged to the <br /> Arkansas River using the lagging factors approved by the State Engineer pursuant to future <br /> Substitute Water Supply (SWSP) approvals. <br /> (e) Indicate the projected amounts of the water sources to supply project water <br /> requirements <br /> Replacement Water: The Miner will obtain an approved Substitute Water Supply Plan from <br /> the State Engineers office every year, providing annually or more frequently the opportunity <br /> to review the sufficiency of water supplies. The SWSP approvals require that the applicant <br /> provide a detailed explanation of the mining operations, a quantification of all mining <br /> activities and subsequent depletions and all legally available replacement sources. <br /> (fJ Affirmatively state that the Applicant has acquired or applied for a National Pollutant <br /> Discharge Elimination System permit from the Water Quality Control Division <br /> The Operator will apply for a COG500000 permit from the Water Quality Control Division of <br /> the Colorado Department of Public Health and Environment prior to discharging water from <br /> the site. <br /> Martin Marietta Materials—Thunderbird Sand and Gravel—MLRB 112 Permit Application <br /> Exhibit G-2 <br />