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The Colorado River supplies >40 million people in the United States Southwest with their daily water supply and is unable to meet the current demands. New approaches are needed to enhance sustainability and resilience. A net zero urban water (NZUW) approach meets the needs of a given community with a locally available and sustainable water supply, without detriment to interconnected systems and the long-term water supply. Transitioning to a NZUW future will require considerable modifications to governance and policy across the Southwest and its cities specifically. We identify five areas of governance and policy challenges: diversified water sources and sinks; planning, design, and operation; monitoring and enforcement; coordination; and addressing equity and justice. Four case study cities are investigated: Albuquerque, Denver, Los Angeles, and Tucson. Across these cities, the policy priorities include supporting potable water reuse, coordinating policies across jurisdictions for alternative water sources, addressing equity and justice, developing and incentivizing water conservation plans, and making aquifer storage and recovery projects easier and more economical to pursue. We conclude that a NZUW transition in the Southwest faces considerable governance and policy challenges, but moving cities toward this goal is crucial. 

Abstract Reducing energy consumption for urban water management may yield economic and environmental benefits. Few studies provide comprehensive assessments of energy needs for urban water sectors that include both utility operations and household use. Here, we evaluate the energy needs for urban water management in metropolitan Los Angeles (LA) County. Using planning scenarios that include both water conservation and alternative supply options, we estimate energy requirements of water imports, groundwater pumping, distribution in pipes, water and wastewater treatment, and residential water heating across more than one hundred regional water agencies covering over 9 million people. Results show that combining water conservation with alternative local supplies such as stormwater capture and water reuse (nonpotable or indirect potable) can reduce the energy consumption and intensity of water management in LA. Further advanced water treatment for direct potable reuse could increase energy needs. In aggregate, water heating represents a major source of regional energy consumption. The heating factor associated with grid-supplied electricity drives the relative contribution of energy-for-water by utilities and households. For most scenarios of grid operations, energy for household water heating significantly outweighs utility energy consumption. The study demonstrates how publicly available and detailed data for energy and water use supports sustainability planning. The method is applicable to cities everywhere.