The City of Patterson (City) is growing and, based on the 2010 General Plan Update, could reach a population of 67,000 (approximately triple the current population) at build-out, with over 50,000 people in 2040. Water demands within the City's service area are expected to rise within the next 20 years. Currently, potable supplies are reliably provided solely by the City's groundwater well network, coupled with some non-potable sources and significant water efficiency measures in on-going programs by the City. While the approach of using conservation and groundwater to serve new growth can still be a solid component of the City's supply for the future, the water resources landscape in California has significantly changed in recent years. There is a realization across all sectors in the water industry that significant transformation may be needed in the way California's water is managed. This has been triggered by the recent drought, which is one of the most severe droughts in the State's history, as well as significant legislation that impacts the way we use and supply water. The Sustainable Groundwater Management Act (SGMA) is part of this new context that may impact the City's ability to rely on historical approaches for supply development. With the expected growth, and the new context and restrictions in which new supplies will be developed, the City embarked in a comprehensive Water Master Plan (Master Plan) to rigorously evaluate potential water supply options and additional conservation measures, and define a cost-effective and sustainable water supply portfolio.