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7 <br />distance (e.g., carex, juncus, and scirpus). Species common in a wide range of elevations and <br />distances included grasses and scouring rush. <br />Although changes in species composition along the elevation gradient were gradual <br />(Table 4), the riparian zone could be divided into upper and lower zones (Figure 5). The <br />upper riparian zone was that area above the level of maximum power plant releases (histori- <br />cally, 4,200 cfs, about 4 ft above the 800-cfs level on the basis of the stage-flow relationships <br />shown in Figure 6) and generally supported facultative wetland and upland plants adapted <br />to mesic, but drier, conditions. Species common in the upper zone included box elder, <br />rabbitbrush, grasses, scouring rush, and golden aster. The lower riparian zone was that area <br />typically within the normal operational fluctuation zone of the river (800 to 4,200 cfs, or 0 to <br />4 ft above minimum) and supported a variety of obligate wetland species. Although much <br />of this vegetation was herbaceous (e.g., common spikerush, cattail, and juncus), some shrubs <br />were also common within this zone (e.g., coyote willow). Along most transects, there was a <br />narrow unvegetated band (average 10.1 ft wide; 0.8 ft elevation above the 800-cfs flow <br />elevation) nearest the river (Table 1). <br />3.2 AREAS OF RIPARIAN ZONES <br />The results of the aerial videographic analysis of riparian zones along the Green <br />River above the Yampa River confluence are presented in Table 5. These values were used <br />in plotting the relationships between flow and area shown in Figure 7. Differences in the <br />flow-area relationships reflect differences in channel morphology in different reaches of the <br />river. The average relationship for the four reaches is also presented in Figure 7.