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2.04.8 Climatological Information <br />• There is very limited climatological data available in the immediate vicinity of the mining <br />operation. A number of agencies and individuals were connected in an endeavor to obtain <br />an adequate data base from which to extrapolate climatological information. <br />Mr. Bob IUrshaw with the Bureau of Land Management (BLM) Planning Department in <br />Durango provided a copy of "Volume I of the Unit Resource Analysis, Step II, Planning <br />Area Analysis .31 Climate for Durango, Pagosa Springs and Vicinity" to the Chimney Rock <br />Mine. In summary, this document describes the average annual precipitation levels as <br />ranging from 18 inches at Durango, to a recorded mean precipitation figure of 23.61 inches <br />in Pagosa Springs. Departures from this mean were recorded as extremes ranging from a <br />low of 10.44 inches to a high of 33.29 inches. <br />Most precipitation occurs December through March as snow. Snow courses in the higher <br />elevations, above 7,000 feet generally have a span of duration from November to April. The <br />lower elevations experience a span of duration as much as two months less than that of the <br />higher elevations. <br />Humidity is relatively low, with the average being approximately 20 percent. Wind direction <br />is typically from the southwest and of low to average intensity. Some high winds have been <br />recorded, but generally only during the early spring months. Gusts have been recorded up <br />to 50 miles per hour. The frost free season ranges from 59 days to 107 days with an average <br />• of 75 days. These figures were recorded for the Durango and Pagosa Springs locals. <br />In addition to the BLM, Mr. Chuck Calkins with the U.S. Forest Service, San Juan National <br />Forest in Durango, provided the Chimney Rock Mine with 11 years of climatological data. <br />The U.S. Forest Service information provided is the result of data gathering which spanned <br />an 11-year period. This period commenced with August 1964 through September 1974. The <br />months covered during that period range from May through October. The source of data <br />collection, Dyke, Colorado, is approximately 7 miles northeast of the Chimney Rock Coal <br />Mine Site at an approximate elevation of 6,500 feet. Climatological Data, Table 7 <br />summarizes the data obtained from the computer printouts provided. The table describe <br />the state of the weather as relates to cloud cover, the number of days in each month during <br />which precipitation occurred, the number of days in each month during which precipitation <br />occurred, the amount of precipitation received in each month, the high and low precipitation <br />occurrence for the month, the average wind speed, high and low variance in wind speed and <br />the wind direction. Due to the lack of consistency in the U.S. Forest Service data, recording <br />of average minimum temperatures and wind direction were not noted for every month <br />described by the computer printouts over the period of time examined. <br />In summary, the U. S. Forest Service data indicates that precipitation received during the <br />months evaluated occurs predominantly as rain, with minor amounts of sleet recorded early <br />in the data collecting period. Spring through early fall precipitation accounts for an average <br />• 2.04-19 <br />