Farm ownership in the San Joaquin Valley highlights different capacities to adapt to changing groundwater regulations

California’s San Joaquin Valley is home to some of the nation’s most productive farmland. Yet, this agricultural productivity has been achieved through unsustainable groundwater use to support irrigation. The Sustainable Groundwater Management Act (SGMA) seeks to address the negative consequences of groundwater overdraft and requires cutbacks in pumping, most notably in 21 critically overdrafted basins, 11 of which are in the San Joaquin Valley. On the pathway towards groundwater sustainability, concern about disproportionate impacts of pumping cutbacks on smaller and less-resourced farms has prompted a closer look at water resources and vulnerability across farm size. In this paper we use county assessor records and other publicly available data to examine how characteristics such as surface water availability, crop type, and economic productivity intersect with farm size in the San Joaquin Valley. We found that small farms (less than 100 acres) make up about three-quarters of farms by count, yet only about 15% by acreage. Medium (100–499 acres) and large (500+ acres) farms had high proportions of field and grain crops, corn, and processing vegetables, while small farms grew more tree crops, vineyards, and irrigated pasture. Notably, small farms tended to be located in areas with higher-than-average surface water availability, with about 30% more deliveries per acre on average compared to areas where large farms were located. Lastly, we examined the potential local water supply impacts of providing preferential groundwater allocations to rural water systems and small farms. While smaller farms face poor inclusion in SGMA planning and implementation efforts, we identify several characteristics that may help them adapt.