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Across the Western U.S., reservoir levels are declining towards protection elevations because of aridity amplified by long-standing operations that release more water than inflow. This paper has the purpose to sketch the effects of reservoir operations that release less water than inflow and evaporation. We use the case of Glen Canyon Dam/Lake Powell on the Colorado River, U.S.A. We programed a new rule in the trusted basin simulation model maintained by the U.S. Bureau of Reclamation. The rule releases 95% of inflow in each time step. The 5% reduction is typically greater than reservoir evaporation. Lake Powell levels stabilize and recover in a few years across a range of assumptions for hydrology and upstream diversions. There remain challenges technically and politically to implement into existing operations the idea to release less water than inflow and evaporation.