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Figure 1. Overview map of the Mancos Watershed. The red numbers refer to the different <br />Marianna <br />hydrogeomorphological and ecological sections of the river as described in the text ( <br />Map by <br />). <br />Young, NRCS <br />surveys to reference conditions that would be typical or expected of an unaltered or unimpacted reach in <br />that section. <br />1.High elevation reaches in the mountains, generally above 2900 meters (9500 feet; see Figure 2A). <br />The streams here are small, straight, narrow and high gradient. The banks and channel bottom are <br />typically either bedrock or comprised of boulders and other material from nearby rock formations. The <br />surrounding vegetation is characteristic of southern Rocky Mountain alpine tundra, sub-alpine, and <br />spruce-fir forests (for descriptions of typical southwestern and Colorado Plateau plant communities in this <br />region, see, for example, Dick-Peddie 1993). Common riparian trees and shrubs in this section include <br />various willows (Salix spp.) and aspen (Populus tremuloides). <br />2. Upper plateau and canyon reaches, generally between 2300-2900 meters (7500-9500 feet; Figure <br />2B). The major tributaries of the Mancos in this section form deep canyons that cut through relatively flat <br />plateaus. The canyon walls are steep, often forming cliffs, and the bottoms are relatively flat. The canyons <br />progressively widen as one moves further downstream. The stream channel tends to be deeper than in <br />reaches further upstream, and the bottom and banks are comprised primarily of cobble and larger material <br />that has been washed downstream from the mountains. In some cases, the channel also exhibits <br />7 <br />