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<br />IV. DISCUSSION AND CONCLUSIONS <br />Areas revegetated in 1985, 1986, and 1987 were quantitatively sampled in 1997 to <br />evaluate revegetation establishment for monitoring purposes. The Osgood Sand <br />Reference Area was also quantitatively sampled to provide the revegetation success <br />criteria values for vegetation wver and herbaceous production for the reclaimed area <br />governed by the requirements of Rule 4.15.8. Parameters sampled in 1997 were <br />compared to the same parameters sampled in prior years using the same sample <br />methods. Tables I1 and 12 provide comparisons of sampling parameter values from <br />1994-1997. This year we also began comparisons of vegetation sampling data with <br />precipitation data from the Keenesburg Mine, in order to better evaluate the effects of <br />local weather conditions on native and reclaimed vegetation communities. <br />1997 PRECIPITATION REGIlVIE <br />The climate of the mine and surrounding area is characterized by a wide temperature <br />fluctuation; from below freezing in winter, to very warm in the summer months. <br />Precipitation in the area is provided by weather systems originating in the Gulf of <br />• Mexico and is most frequent and reliable during the spring and summer months (Table <br />10). <br />Coors Energy Company has collected precipitation data at the mine for a number of <br />years. This data represents the most complete record of precipitation from the mine <br />area. Table 10 presents a summary of precipitation data collected from 1993 through <br />1997, corresponding with the most recent vegetation monitoring. A review of the data <br />illustrates that precipitation is lowest during the autumn and winter months (October <br />through March) and higher from spring through late summer. The months with the <br />highest average precipitation are May and June. Based on the 1993-1997 data, average <br />yearly precipitation was calculated. Additionally, an average "growing season" <br />precipitation was calculated based on the months with reliable precipitation which was <br />most likely to impact vegetation growth during a specific growing season (January- <br />July). From this average, comparisons of individual yearly precipitation and it's effect <br />on specific growing seasons can be made. <br />Total January-July precipitation for the 1997 season was 6.47 inches. This translates <br />into a 5.6 percent negative departure from the January-July precipitation in 1996. Of <br />further note is that the 1996 January-July precipitation was a 38.6 percent departure <br />from the very wet 1995. <br /> <br />-13- <br />