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precipitation in July 2011. The abundant cold- season precipitation created above average snowpack <br />levels for the region. These wet months combined with a wet summer left precipitation total for the 12 <br />months preceding sampling well above average (Figure C -8b). In general, 2011 was the wettest and <br />coolest observed in the last 26 years. In contrast, the winter and spring preceding 2012 sampling was <br />very dry, with precipitation well below average (Figure C -7b). March, April, May and June of 2012 also <br />had below average precipitation. As a result, precipitation for the 12 months preceding sampling was the <br />second lowest in the last 26 years, with 2002 being the lowest (Figure C -8b). The first six months of 2012 <br />were also the warmest in the last 26 years (Figure C -11). <br />Sample Adequacy Calculations <br />Sample adequacy based on all -hit allowable herbaceous cover was achieved in BRB -1 and each of the <br />reference areas except the Mountain Brush Reference Area. Thus, the alternative of using the upper <br />90% probability value of the mean was exercised. It can be assumed that the CDRMS minimum sample <br />size (15) is intended to produce a reasonable estimate of population variance [which is true based on <br />experience]. Given this, then data from the 18 samples of the Mountain Brush Reference Area likewise <br />establishes a reliable estimate of population variance. Using this variance estimate, the maximum <br />possible value of mean all -hit allowable herbaceous cover (with 90% confidence) was taken to represent <br />the contribution of the Mountain Brush Reference Area to establishment of the cover performance <br />standard (see below). Details of the calculation of allowable herbaceous cover for each area are provided <br />in Tables G -1 through G -5. <br />2012 Assessment of the BRB -1 for Compliance with Phase III Performance Standards <br />COVER <br />As described above, in 2012, sample adequacy based on all -hit values was achieved for BRB -1 and each <br />of the reference areas except the Mountain Brush Reference Area. Thus, in consideration of the lack of a <br />sample size sufficient to detect a 10 percent reduction in the mean with 90 percent confidence (i.e. <br />sample adequacy), the upper limit of the possible values of the true mean (with a sample size of 18) was <br />determined. This can be done in either of two ways. <br />1) Confidence Intervals <br />s 11.4 <br />C.I. = — + = F1.740 =4.66 <br />18 <br />18 <br />