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1. The lessee will make an inventory of the tract, under the require- <br />ments of the Colorado State Director, for significant paleonto- <br />logical resources prior to approval of the mining permit required <br />by 30 CFR 710.11. If such resources are found, the mining permit <br />will be modified to protect such resources or a salvage plan will <br />be devised and made a part of the mining permit. <br />III. DESCRIPTION OF THE AFFECTED ENVIROPEdENT <br />CLII•tATE AND AIR QUALITY <br />The climate of Southwestern Colorado is semi-arid, characterized by warm <br />to hot summers, cold winters, and a limited amount of precipitation each <br />year. No climatic data exists for the proposed lease site; however, <br />temperature and precipitation data are available from the Fort Lewis <br />recording station four miles to the east of the proposed lease area. <br />The climatic conditions at the mine site should not differ significantly <br />from the Fort Lewis data. The average monthly temperatures recorded at <br />th~ Fort Lewis Station range from a bow of 23 F in January to a high of <br />64 Fin July. temperatures below 0 Fare not unusual and temperatures <br />in excess of 100 Fare rare. The average length of the frost-free _ <br />season, defined as the bength of time between the last 32 F spring <br />freeze and the first 32 F fall freeze, is 96 days. <br />The Fort Lewis Station receives approximately 19 inches of precipitation <br />each year, averaging no more than 2.1 inches and no less than 0.9 inches <br />per month. F1ost of the precipitation between November and Plarch falls <br />as snow with the average snowfall being 82 inches. Thunderstorms <br />account for most of the summer precipitation. <br />The prevailing surface winds are from the southwest and west directions. <br />The closest air quality monitoring sites to the proposed lease area are <br />Durango and I.1esa Verde. Neither site measured total suspended parti- <br />culate (TSP) levels above the Colorado or the National Ambient Air <br />Quality Standards (CAAQS, NAAQS). This standard is 65_ug/m (annual <br />geometric mean, AGPI). The Mesa Verde site is representative of the TSP - <br />levels expected just upwind of the proposed lease site. The TSP levels _ <br />at Ftesa Verde were below 20 ug/m3 (AG11) for 1978 and 1979. <br />The closest Federal Class I Prevention of Significant Deterioration <br />(PSD) area and Colorado Category I PSD area is the Mesa Verde National <br />Park, located 12 miles west of the mine. <br />G <br />11 <br />