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. /",JCc . . . .., .., '.~~' -. l,"' . /" banks and point bars, would become colonized by vegetation above the flood ~/< level of the new flow regime. . Reductions in annual sediment supply to the Yampa Canyon also will affect the river channel to some degree. In the Yampa Canyon, extensive net degrada- tion of long reaches of the channel that often accompanies a sediment budget deficit probably will not occur because the channel flows on bedrock, talus, and coarse debris from tributaries. If the sediment load is drastically reduced, local erosion of sand from some beaches, bars, and pools may occur, as it has in places on the Colorado River below Glen Canyon Dam (Howard and Dolan, 1981). The nature of changes in the river channel of the Yampa Canyon that would accompany a: long-term surplus in the sediment budget are more difficult to ascertain. The sediment supply to Yampa Canyon is equal to sediment transport through Deer10dge Park. Average channel slope through the Yampa Canyon is much greater than channel slope through Deer10dge Park; therefore, all sedi- ment supplied from Deerlodge Park should be transported through the Yampa Canyon on a long-term basis. However, on a year-to-year basis, problems due to aggradation could occur locally in the Canyon where there are low river gradients over short reaches. In summary, any change in river-streamflow regime or sediment supply will cause adjustments in channel hydraul i c characteri sti cs, and changes in the variables of a river system will be such that hydraulic adjustment will be minimized (Langbein, 1964). At best, only general predictions can be made about the' types of adjustments that wi 11 resu1 t from changes in hydro 1 ogi c conditions. By the same reasoning, it is difficult to identify precise levels of reduced annual streamflow and anticipated sediment supply that will result in minimal alteration of a river reach from its existing character. Estimates of the sediment surplus or deficit at Deer10dge Park for several given streamflow frequency distributions, and various annual total sediment loads and annual sediment supplies from upstream are given in the sediment budget in table 6. The estimates are based on prevailing hydraulic conditions of slope, 'channel geometry, velocity distribution, stage-discharge relation, sediment diSCharge-water discharge relation, and sediment size. This table cannot be used to predict specific or local geomorphic responses if the system is thrown grossly out of balance, but it can be used as a management tool to identify possible changes in channel equilibrium resulting from reduced mean-annual streamflow or sediment supply. Other streamflow-duration curves, such as those based on streamflow require~ents specified from biological studies, may be substituted in computations to estimate annual sediment loads. Likewise, sediment-supply scenarios may be adjusted as more specific information becomes available to identify the location and efficiency of potential sediment trap areas in the Yampa basin. SUt,~t,te,RY AND CONCLUSIONS The P;l:/s;cal and biologi:a1 character of the YaGlpa River ;:1 Dinosaur 'I ..&.' , '" ......,. .,.. d ~ ~ I .., . .&. ~l . . i'H~ \,0 1 ona I j.lcnumen I,. prl mal"l IY j S c:cnr.ro. Ie ....y i.,tie preva 1 11 i1g S 4reai11i- 0'." regl me and transported sediment, Pre~~rving the physical and biological environment of the Yampa River through Deerlodge Park and Yampa Canyon will require main- tenance of a range of streamflows for a given sediment supply over a period of 30