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The average annual yield of 16,100 acre-feet translates to about 390 acre-feet per square mile per <br />year. Comparing this value to that of the North Fork (628 acre-feet per squaze mile per yeaz) <br />illustrates the lack of runoff from the coal lease area watersheds. The decrease in runoff is <br />primarily a function of decreased precipitation at the lower elevations. <br />The highest gaged flows were recorded on May 28, 1993, during runoff of a wet-yeaz snowpack. <br />The daily mean gage flow was 340 cfs and the instantaneous flow peaked at 359 cfs. <br />Permit Area Watersheds <br />WWE and Mr. Ernest Pemberton, P.E. (former Chief Engineer for the U.S. Bureau of <br />Reclamation, Sedimentation and River Hydraulics Section) have conceptually quantified the <br />stream hydrology and sediment transport chazacteristics for watersheds within the Apache Rocks <br />and the Box Canyon permit revision azeas (PR06 and PR08, respectively). A report summarizing <br />this work for these permit areas is included in this document as Exhibit 55. <br />A new evaluation (Exhibit SSA) was prepared for the South of Divide permit area. The <br />discussion below focuses on the South of Divide area; however, Exhibit 55 has been <br />retained in the permit since mining activities continue in the Box Canyon area. <br />Figure 1 in Exhibit SSA shows the drainage basins for 14 stream channels in the South of Divide <br />permit area. Each basin has an identification number that will be used throughout this discussion of <br />• stream channel parameters and subsequent changes. Table 14 identifies which streams in the <br />permit area have drainage basins that overlie the South of Divide mining azea. As shown in Table <br />14, the mine panels will underlie portions of twelve separate minor tributaries of the Dry Fork and <br />Lick Creek. The remaining two basins were determined to be outside the influence of mining. <br />Table 14 <br />Ba in in the Permi Ar a Overl in Pro o d Minin Area <br />Basin <br />No. Overlying <br />Pro osed Minin Outside of <br />Pro osed Minin <br />4 X <br />5 X <br />6 X <br />26 X <br />27 X <br />28 X <br />29 X <br />30 X <br />31 X <br />32 X <br />33 X <br />34 X <br />35 X <br />36 X <br /> <br />L~ <br />2.04-99 Revised November 2004 PR10 <br />