Federal management of water is undergoing a change that involves a drastic reduction in the number of new water projects and an increase in emphasis on the quality of water management. This book summarizes and analyzes environmental research conducted in the lower Colorado River below the Glen Canyon Dam under the leadership of the Bureau of Reclamation. It reviews alternative dam operations to mitigate impacts in the lower Colorado riverine environment and the strengths and weaknesses of large federal agencies dealing with broad environmental issues and hydropower production. While many problems remain to be solved, the Bureau of Reclamation through the Glen Canyon area. The lessons of GCES are transferable to other locations and could be the basis for a new era in the management of western waters.