Aligning the multiple goals of food production, environmental flow provision, and nutrition in US watersheds

Food production is the main consumer of water across the United States. In the Western US in particular, the relative paucity of water resources combined with the ever-growing water demands of food production have meant that many watersheds in the region are experiencing substantial streamflow depletion. Numerous efforts are being undertaken to address this unsustainable water use and to better provide for environmental flows for natural systems. Yet many of these stressed watersheds also play an important role in meeting the nutritional requirements of people across the country and globally. Thus strategies to improve environmental flows must also ensure that they do not compromise the nutritional supply of food. To this end, we seek to identify opportunities for alleviating streamflow depletion while continuing to meet (or improve) national supplies of key nutrients (e.g., calories, protein, iron) based on the following questions: 1) How many people can be adequately fed by food production in each watershed? and 2) What fraction of each consumer's nutrient supply is sourced from 'depleted' watersheds? Using information on crop production, nutrient content, and recommended dietary intakes, we calculate the number of people able to have their nutritional needs met by food production in each watershed and combine this with recent (year 2012) data on streamflow depletion due to food production for ~2000 watersheds across the contiguous United States. We then utilize information on the trade of food commodity groups with economic input-output models to link places of nutrient production with places of food consumption and calculate the fraction of each destination's nutrient supply that is sourced from watersheds experiencing streamflow depletion. This improved understanding can help to prioritize watersheds for intervention and to tailor strategies that incorporate the nutritional importance of a watershed.