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Water Supply Scarcity in Southern California: Assessing Water District Level Strategies

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Urban water scarcity is an ongoing reality in California, especially, in Southern California with its arid climate and cyclical droughts. Southern California relies on upstate water imports provided by the Metropolitan Water District of Southern California (MWD) for a significant portion of its water supply. MWD also imports water from the Colorado River, conveyed through the Colorado River Aqueduct. Key to the transportation of water from the mountains in Northern California to the south is the Sacramento-San Joaquin River Delta, vulnerable to aging levees, subsidence and saltwater intrusion. In addition, the environmental deterioration of the Sacramento-San Joaquin River Delta, habitat to several endangered species, has led to ongoing restrictions on MWD water deliveries to Southern California water agencies. This has renewed efforts to both provide for the environmental improvement of the Delta ecosystem, as well as to find a solution for water conveyance, either through a canal, or more recently, through twin tunnels. In addition, the susceptibility of the Sacramento-San Joaquin River Delta to a major Bay Area earthquake increases the threat of disruption of water imports for Southern California. Climate Change Amplifies Reliability Challenges. The reliability of water supply for Southern California is thus already precarious. Climate change impacts will further aggravate water scarcity throughout the State. According to the State’s Climate Adaptation Strategy (2009), snowpack in the Sierra Nevada mountains, a major state source of water storage, is already decreasing and climate change models indicate that precipitation in the mountains will be increasingly in the form of rain, not snow. The State relies on the runoff from the snowpack in the Sierra Nevada to provide water during the warmer months from late spring to early autumn, especially for the southern part of the State. The Climate Adaptation Strategy estimates that the snowpack may be reduced from its mid-20th century average by 25-40% by 2050. Climate change impacts for the State also include a 12-35 % overall decrease in precipitation by midcentury.

California’s Water Conservation Efforts. To deal with water scarcity, the State initiated in the early 1990s a voluntary urban water conservation program managed by the California Urban Water Conservation Council (CUWCC), which promoted the implementation of Best Management Practices (BMPs) to achieve more efficient water use. In response to the Governor’s call for an aggressive urban water conservation plan, in 2009 state agencies with water policy responsibility developed a plan with a target of reducing urban water use through conservation measures by 20% by 2020. This target was incorporated into the 2009 Comprehensive Water Package that was passed by the California legislature in November of 2009. The Water Package (CA Dept. of Water Resources 2009a) included an $11B bond issue that was to be voted upon in the November 2010 ballot, allocating several billion to fix the Delta, and funding for conservation and other water initiatives, including the development of Integrated Water Management Plans. As part of the 2009 state legislation, regional and local water districts were required and provided incentives to enact conservation and other measures to develop “diverse regional water supply portfolios that will increase water supply reliability and reduce dependence on the Delta” (S.B. X7-7, Sect. 1, Part 2.55, Chapt. 10608 (c)). Urban water agencies are required to report their baselines and targets to meet 20 x 2020 goals in their Urban
Water Management Plans (UWMPs), which are updated every five years.

Study Objectives
Assessing the Effectiveness of Conservation Strategies.

Analyzing the Cost-Effectiveness of Strategies.

Identifying Robust Strategies for the Future.

Hilda Blanco
L. Stott
M. Alberti
Research Areas
Urban Systems and Built Environment
Water Resources
Publication Type
Digital Object Identifier
Full Citation

Blanco, H. P.I., Co-PIs: J.P. Newell (U. Michigan); L. Stott (USC); M. Alberti (UW). (2012) “Water Supply Scarcity in Southern California: Assessing Water District Level Strategies.” Los Angeles, CA: Center for Sustainable Cities, Price School of Public Policy, University of Southern California. 1-80.