Irrigation is increasingly important to agricultural production and supply chains in the United States. Irrigation provides an important buffer to crop production and supply chains during drought, although unsustainable water use poses a long-term risk to agriculture. In this study, we ask: 1. What are the surface water, groundwater, and groundwater depletion footprints of agricultural production for counties within the United States, 2. How much irrigation water is embedded in domestic transfers of agricultural commodities in the United States, and 3. How much do these domestic transfers of agricultural goods rely on renewable vs. unsustainable groundwater use? To answer these questions, we quantify the irrigation water footprint of crop production for counties within the U.S., as well as the irrigation embodied in agricultural commodity fluxes between counties in 2012 and 2017. Overall, we find that in 2012, 199.0, 219.1, and 408.0 cubic meters of water were embedded per ton of commodities and 5.64E10, 1.67E11, and 1.03E11 cubic meters of water were transferred domestically for grain, produce, and animal feed, respectively. In 2017, we find that 113.6, 143.91, and 444.5 cubic meters were embedded per ton of commodities and 1.80E11, 1.26E11, and 8.66E10 cubic meters of water were transferred domestically for grain, produce, and animal feed respectively. Unsustainable groundwater withdrawals accounted for 21.2% and 22.0% of all water embedded in domestic agricultural supply chains in 2012 and 2017, respectively. Our results highlight the long-term risks that reliance on unsustainable groundwater use poses to the national food supply and greater agricultural supply chain.
