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~ The upper Colorado River can be classified as a supply controlled river in terms of sediment transport. This means that the volume of sediment transported _by the system is controlled by the supply, rather than sedi- ment transport capacity. Throughout the system, the ma- jority of the river has a sediment transport capacity many times greater than the supply. This is evidenced by the fact that although the river transports -mainly wash and sand load, the bed is comprised of gravels, ~ cobbles and boulder~. If the supply of sand was closer to the actual transport capacity, the river bed would contain a much larger percentage of sand. Only in iso- lated reaches, which have flatter gradients, is there evidence of a large percentage of sand in the bed. As a result of its supply control nature, the Colorado River does not have a significant potential for aggrad- ation, since the river has more than enough hydraulic power to transport the incoming sediment load. This, , icombined with the river's low potential for degradation because of the controlling effect of geologic format- ions and the armored stream bed contribute to form a Lhighly stable river. Analysis The possible effect of water development projects on geomorphic aspects of the Colorado River. can be divided into two parts, channel maintenance and channel flushing. Channel Maintenance Will reduced peak flows result in unstable channel conditions? The above information indicates that a~gradation will not occur (as contrasted with the Green River, wher~ Andrews' (1986) study indicates that decreased sediment transport in the downstream direction is associated with aggradation and decreased channel 2