ABSTRACT
The ecosystem of the Grand Canyon has been drastically altered since the closure of Glen Canyon Dam in 1963. Specifically, the habitats created by the Colorado River and the tributary debris flows that enter it have changed as the flow regime of the river has shifted. Debris flows create habitat through the formation of fan-eddy complexes at the mainstem-tributary intersections. Sandbars, return-current channels, backwaters, marshes, and high-water zones are all affected by these intersections, and the flora and fauna that they support is dependent upon the sediment input from debris flows and the water released from Glen Canyon Dam. An in- depth understanding of the effects of current dam management on habitat creation, degradation, and maintenance is essential if we wish to successfully conserve and manage the Grand Canyon ecosystem. Managing a system as diverse and as historically altered as the Grand Canyon requires integrating all of its physical and biological components. Many habitats have been identified within the Grand Canyon—what remains is to gather as much information as possible about the physical features and the ecology of each so that judgments can be made about which ecosystem features are worth maintaining and the correct actions can be taken.