California’s Sustainable Groundwater Management Act (SGMA) of 2014 established oversight of the state’s groundwater basins and subbasins. The history of water rights in the Pomona Valley, east of Los Angeles, suggests that local control of water will not be a straightforward process. From the mid-nineteenth century, white settlers in this valley battled for control of its surface and groundwater. After decades of legislation and controversy, the Pomona Valley Protective Association (PVPA) emerged. Its membership included agricultural interests, communities, and mutual water companies in a scheme to capture storm water flowing off the San Gabriel Mountains and percolate it via spreading fields to recharge groundwater supplies. This cooperative venture combined water conservation with flood control, a pattern that might be replicated in the coming years as other California water basins struggle to comply with SGMA.