摘要：Objectives. To determine how urban water conservation strategies in California cities can affect water and energy conservation efforts, reduce greenhouse gas emissions, and benefit public health. Methods. We expanded upon our 2014 health impact assessment of California's urban water conservation strategies by comparing the status quo to 2 options with the greatest potential impact on the interrelated issues of water and energy in California: (1) banning landscape irrigation and (2) expanding alternative water sources (e.g., desalination, recycled water). Results. Among the water conservation strategies evaluated, expanded use of recycled water stood out as the water conservation strategy with potential to reduce water use, energy use, and greenhouse gas emissions, with relatively small negative impacts for the public’s health. Conclusions. Although the suitability of recycled water for urban uses depends on local climate, geography, current infrastructure, and finances, analyses similar to that presented here can help guide water policy decisions in cities across the globe facing challenges of supplying clean, sustainable water to urban populations. Climate change, increasing water demands, drought, and impaired water quality render water supply a critical issue across the world. In California, a state subject to serious drought, water use is linked to energy use and greenhouse gas (GHG) emissions because most water is transported hundreds of miles from sources to users. As a consequence, water conservation strategies in California have potential to decrease carbon emissions and benefit human health. Water, energy, and health are intricately linked. 1–3 As a result, the health impacts of new water management policy and energy use policies and programs should be systematically assessed when programs and policies in these arenas are proposed, implemented, and evaluated. This is particularly true for the American Southwest, and other Mediterranean climates, including California, which is currently experiencing a prolonged drought and is projected to face water shortages going forward. 4–6 Our analysis focuses on Southern California as a model for how choices in water sources can have an impact on human health. To address the prospect of long-term water shortages, California implemented aggressive water conservation legislation in 2009, which included calls for each of California’s nearly 400 urban water districts to decrease water use by 20% by 2020 (The Water Conservation Act, Senate Bill X7-7). 7 In addition, during the 2014 election, California voters approved a $1 billion water bond, and in the spring of 2015, California Governor Jerry Brown called upon urban water suppliers to cut water use by 25% from their 2013 usage levels. 8 The goal of each of these initiatives was to decrease demand for water across the state, so that this demand is in better alignment with current and projected water resources. Senate Bill X7-7 mandates that each urban water district develop and implement a water management plan, but it does not specify how to achieve those reductions. Although the legislation does not mandate the mechanisms for reducing water use, it does list 14 “demand management measures” as suggested areas on which to focus water conservation actions. 9 Likewise, the governor’s mandate requires urban water districts to conserve water, but does not specify how each district should achieve this goal. 8 In deciding which strategies to implement, urban water districts have a unique opportunity not only to decrease water consumption overall, but also to implement those water conservation strategies that have secondary benefits to health. To help urban water districts choose conservation strategies that maximize the potential health benefits and minimize potential harms to health, we recently completed a health impact assessment (HIA) of urban water conservation in California. 10 This work expands on our observation that the water–energy nexus is a significant source of negative health impacts, especially when coupled with climate change. Here, we discuss 2 different urban water conservation strategies that have the greatest potential to decrease energy use and GHG emissions in California: landscape irrigation bans and expanded use of alternative water sources (e.g., desalinated or recycled water). We discuss the health impacts of each of these strategies and compare them to the status quo. We discuss the important role that public health professionals can play in helping their local water districts to adopt strategies that are conducive to both conserving water and improving the health of their constituents.
