Reclamation’s 2021 West-Wide Climate and Hydrology Assessment investigates changes in climate and hydrology across the West using approaches that align with the 2011 and 2016 Reports and new techniques, data, and analyses that provide a richer assessment of future changes to support water management in the West. This work relies on the best available information and well-vetted methods, using approaches documented in peer-reviewed literature. However, uncertainties still exist, including those associated with climate projections and assessing hydrologic impacts, as discussed in the Uncertainty Explained page (button on right). This work is performed by Reclamation’s Technical Service Center in partnership with the United States Geological Survey (USGS), University of Arizona, Columbia University, Desert Research Institute, National Center for Atmospheric Research, Aspen Global Change Institute, and in collaboration with Reclamation Regions and Area Offices. Explore these pages to see what is in the full 2021 Assessment report.