NEWS NOTES ON SUSTAINABLE WATER RESOURCES California Recycling and Groundwater Depletion Badiuzzaman, Pierre, et al, Can Ocean Desalination and Water Recycling Capacities Substitute for Groundwater Depletion in California?, Univ. of St. Andrews, Paper 2017-09. https://pdfs.semanticscholar.org/bab5/d560e3d515eccab5f6b2d99cddce48347993.pdf ; While the sustainability of resource depletion is a longstanding environmental concern, wider attention has recently been given to growing water scarcity and groundwater depletion. This study seeks to test the substitutability assumption embedded in weak sustainability indicators using a case study of Californian water supply. The volume of groundwater depletion is used as a proxy for unsustainable water consumption, and defined by synthesizing existing research estimates into low, medium and high depletion baselines. These are compared against projected supply increases from ocean desalination and water recycling by 2035, to determine whether new, drought-proof water sources can substitute for currently unsustainable groundwater consumption. Results show that maximum projected supply of new water, 2.47 million acre-feet per year (MAF/yr), is sufficient to meet low depletion estimates of 2.02MAF/yr, but fails to come near the high baseline of 3.58MAF/yr. This does not necessarily indicate physical limitations of substitutability, but more so socio-economic limitations influenced by high comparative costs. By including capacities in demand-substitutability via urban water conservation, maximum predicted capacities reach 5.57MAF/yr, indicating wide room for substitution. Based on these results, investment in social and institutional capital is an important factor to enhance demand-side substitutability of water and other natural resources, which has been somewhat neglected by the literature on the substitutability of natural resources. This study will also be linked on the 2017 Reports and Publications Page of the Sustainable Water Resources Site at https://sites.google.com/site/sustainablewaterresources/ ">https://sites.google.com/site/sustainablewaterresources/ ; Tim SmithSustainable Water Resources CoordinatorGovernment Web Site, https://acwi.gov/Sustainable Water Resources Site, https://sites.google.com/site/sustainablewaterresources/ ">https://sites.google.com/site/sustainablewaterresources/ ;