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where: <br />E = equitability <br />d = observed species diversity <br />d = maximum species diversity = logZS <br />max <br />S = number of species in sample. <br />A Student's "t" test was used to evaluate statistical differences <br />between mean total macroinvertebrate densities at each station. The <br />-- following example equation represents the procedure for the test: <br />X1 - Xy <br />> to <br />S.E. <br />P <br />where: <br />%1 = mean observed at Station 1 <br />S2 = mean observed at Station 2 <br />.~ <br />• <br />S.E.p = pooled standard errors <br />to = t value at the desired level of significance. i~ <br />2.3 Fish <br />Electrofishing was conducted in a portion of the iiilliams £ork <br />River located approximately 0.8 km (0.5 miles) from the confluence with <br />the Yampa. River using a Coffelt Backpack Shocker (riodel BP-5). Two <br />transects were established is relation to the coal silo (Figure 1). The <br />upstream transect (A to B) included the portion of the river from the <br />silo to approximately 300 yards (275 m) upstream, while the downstream <br />transect (C to D) ranged between the silo and Coal Road Bridge about <br />700 yards (650 m) in length. One person held the electrodes and walked <br />upstream, while one or two people trailed behind the shocker and netted <br />fish. Each transect was shocked is approximately 75 to 100-yard <br />sections (69 to 92 m), which included both shorelines. Fish captured <br />along each transect were placed is a large container. Lengths and <br />" weights were taken for all fish exceeding 100 mm total length except <br />minnows. Important recreational fish (Family Salmonidae) were weighed <br />I- and measured immediately after collection to reduce chances of ~~ <br />J <br />mortality. <br />4 <br />