This paper examines the security of water resources in Phoenix, AZ, under different scenarious of climate change, consumption patterns, and reductions of available surface water. phoenix constitutes a key site for examining the projected effects of climate change on water reources in the US West. Water providers in Phoenix rely on a mix of water sources to deliver to their customers. These include groundwater, water from the Salt and Verde River watersheds, water from the Colorado River, an deffluent (water reuse). Water providers in Phoenix vary in terms of their access and rights to different sources of water for municipal delivery. As a result, providers differ in terms of their exposure to cut-backs in available water. To assess vulnerability to climate change and reduced water resources available for deliver, we consider two primary questions. (1) Based on current water provider portfoloio mixes, what is the current relative security of each provider's mix of water sources? (2) Using three different climate change scenarios for the Wester USA and projected growth-related deamnad increases, what patterns of water supply vulnerabilites are likely to manifest for themselves in 2020? We map projected supply shortages and discuss implications for the vulnerability of people and places and mitigation strategies.