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.. channelization, and streambed manipulations which have no direct effects on water quality, but which eliminate the natural habitat of the whitefish. This transition zone is followed by meandering stream reaches which generally are found in agriculturally developed areas, have higher silt loads, and in which are found various minnows, catfish, and carp. Carp are an introduced species which have become established as an important part of the Colorado River fish community. Canyon reaches have the high- est silt load, and fish (e.g., humpback sucker) in these reaches (exclusive of piscivores) are generally dependent on food materials which are washed ^' t in from tributary streamS. Terrestrial Ecosystems. The terrestrial component of the Colorado River basin is largely made up of open range, desert, and some forests, ~ Lo as indicated by figure 3 which displays the major vegetation types occur- r ring in the Colorado River Basin. The 37,500,000 acres of upper basin ~ .. rangelands fall into four specific vegetal communities; namely, (1) grass, ~ .. CALIFORNIA w (2) northern desert shrub, (3) southern desert shrub, and (4) salt desert .- .. x C o shrub. Rangelands in the Colorado River Basin are, in fact, put to multi- ::- .. ... .. ple uses, including grazing, recreation, wildlife production, and watershed areas. About 92 percent of the rangeland is used for grazing. Most of the rangeland supports wildlife to some degree, and large portions are also used for recreation including horseback riding, hunting, touring, camping, and visiting wilderness areas. Kev .. note: most areas overlal' cODsiderably ~ ~ - ~ ~~ The forest land in the Upper Colorado River Basin is defined by the u..T.[D lTATtl OI"'''.TII(lIT 0' TII[ '''TII:_.O_ IVIU"u 0' ."Cl.AIIATIO. higher elevation trout waters (> 5,000 ft) tranlition reaches .. trout and other species meandering stretches.. lower velocities canyon areal.. higher velocities, silt-laden reservoir tailwaters .. cold reservoir tailwater. - warm COLORADO RIVER BASIN forest vegetation which ranges from the spruce-fir forest at high eleva- QUALITY O' WATER IIAP .. .... n .. ... ._ ICilLlor IIIL[5 tions through lodgepole pine, douglas fir, and quaking aspen to ponderosa 1""---., , , ....---... 0-400.70 ."..., n, ItIIl M:"1IUl u:o.r.... filM pine, mountain brush, and finally to the pinyon-juniper foothill areas. Figure 2. Generalized Ecotypes Based on Expected Distribution of Specific Fishes in the Colorado River Basin (reservoirs not included)