Sustainability Review of Water-Supply Options in the Los Angeles Region

The City of Los Angeles, with a population reaching 4 million people in 2013, imports nearly 90% of its water from sources outside the city. However, climate change, population growth, competing demands, water quality concerns, and environmental restoration projects all have a large impact on Los Angeles' dependency on future water importation. In this study, a system characterization was performed to assess each of the water sources that supply Los Angeles and the factors affecting them under present and potential future conditions. Additionally, water demand and conservation methods in Los Angeles were examined to understand their impact on the overall water supply system. Of the five main water sources that supply Los Angeles-Los Angeles Aqueduct, Colorado River, California Aqueduct, local groundwater, and reclaimed water-a majority will be impacted by climate change, water quality, energy, and cost constraints. While the expansion of water demand management and agricultural water transfers can help address the challenge of increasing demand, the impacts of climate variability and competing demands are likely to constrain their potential. The characteristics of the Los Angeles water supply system provide the basis for a system sustainability assessment that bounds the options for solutions to meet both a growing demand and the need for climate change adaptation. (C) 2015 American Society of Civil Engineers.