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0 -5- <br />Considering only these physical characteristics one might <br />conclude that the two rives were much the same historically with <br />but slight differences in the timing of flow, but with significant <br />differences between them when one considers the fluctuations between <br />low and high flows. The Green River above its confluence with the <br />Yampa would have to be considered the more stable in terms of flow <br />b regimen. <br />Other evidences also exist to indicate that the two rivers above <br />their confluence were similar in character. Woodbury (1963) found a <br />comparable array of algae species in the two rivers. 'Woodbury (1963) <br />D also found similarities with the aquatic invertebrates inhabiting <br />these two sections. Both rivers can be characterized by the <br />preponderance of functional collectors and grazers indicating streams <br />processing autotrophic production and fine particulates most likely of <br />autrophic origin (Appendix I, pp 81, 97). <br />Species composition of the fishes present were also similar <br />(See McDonald and Dotson, 1960; Azevedo, 1962; and Baily and <br />Alberti, 1962). The fish communities included endemic Colorado <br />10 River species as well as substantial populations of introduced <br />species. The closure of the dam along with the rotenone treatment <br />clearly affected the fish population in the Green River at least to <br />its confluence with the Yampa and possible for some distance below. <br />Endemic species disappeared from the Green immediately below the <br />dam and recurred gradually downstream until at Echo Park the original <br />(pre closure) community composition seemed the rule (Binns, et al., 1963; <br />Banks, 1964; Vanicek, et al., 1970; Holden and Stalnaker, 1975; <br />McAda and Wydoski, 1980). <br />The fact that the fifth order Yampa and Green Rivers before dam <br />closure were reasonably similar and that since closure changes in the <br />Green River are well documented suggests that some effects of changes <br />in water use on the Yampa can be anticipated. These differences <br />further support the conclusions drawn by Annear, 1980 (See <br />Appendix, pp 97 -104). <br />Ib <br />Ib