Pumping for the masses: evolution of groundwater management in metropolitan Los Angeles

Groundwater supports many aspects of human life. In cities, groundwater can provide a cost-effective source of water for drinking and industrial uses, while groundwater basins provide storage. The role of groundwater in a city’s water supply tends to change over time. In the Los Angeles metropolitan area, groundwater is critical. Over decades, users in the region’s many basins allocated annual pumping rights to groundwater among users through adjudications. These rights were determined through collective processes over decades, which contributed to the complex array of public and private organizations involved in water management. The rights also continue to evolve. We analyzed changes in the distribution of groundwater rights over time for adjudicated basins in Southern Los Angeles County. Results indicate that groundwater rights are increasingly: (1) controlled or regulated by public institutions and municipalities, and (2) consolidated among larger users. Yet, both the percentage of total supplies provided by groundwater, as well as the distribution of groundwater rights, varies widely among cities and communities throughout Los Angeles. As metropolitan Los Angeles faces reduced water imports and emphasizes local water reliance, access to pumping rights and storage capacity in groundwater basins will become even more vital. We discuss implications of our results for future urban water management.