PSII-16 Opportunities and challenges related to water use intensity and its effects on sustainability within the U.S. beef supply chain.

Abstract The United States (U.S.) is a major beef producing and consuming country and increasing demand for beef is expected to apply additional pressure on non-renewable water resources. Water footprints of beef production are widely documented in the literature and are a contentious issue. The sustainability of water use in beef production is typically assessed through virtual water footprints (VWF) and life cycle assessments (LCAs). However, ongoing debates persist regarding whether water footprints should be volumetric or impact-based assessments. Distinct differences in the methodologies of VWF and LCA introduce challenges for policymakers who aim to redistribute water resources along the beef supply chain to improve sustainability. Here, we summarize the challenges and opportunities associated with water use in the U.S. beef supply chain by synthesizing findings from 71 studies spanning multiple disciplines, including geology, hydrology, water resources, sustainability, livestock production, economics, and policy from 1993 to 2024. The primary challenge identified was the lack of comparability between VWF and LCA studies. Inconsistencies in accounting for green, blue, and grey water footprints, varying functional units, and different system boundaries complicate across-study comparisons. The discrepancies observed between studies are often related to data deficiencies, requiring the implementation of some generalized assumptions. Furthermore, VWF tends to quantify water footprints on a regional or national basis, while LCAs are usually conducted locally. Consequently, resource management initiatives informed by regional-level figures may not have the desired effect on mitigating local water resource stressors. An essential step in addressing these challenges is improved data collection in the form of standardized methodology, functional units, and system boundaries to ensure targeted and meaningful data acquisition. An additional opportunity to address some of the data deficiencies is technology adoption. For example, on-farm camera sensors or stand-alone water monitoring devices can measure direct water consumption. Additionally, the installation of real-time water flow monitoring systems in beef processing plants has the potential to reduce water footprint through improved plant management. The adoption of technologies such as remote sensing and improved irrigation applicators has reduced the water footprint of crop production and, subsequently, the beef water footprint as well due to the impact of irrigation on cattle feed footprints. Continued improvements in water use efficiency and management through technology adoption, as well as the implementation of standardized methods for assessing water footprints, are critical for generating comparable data that can inform policy-making decisions in the U.S. beef industry.