The objective of this major project is to evaluate climate change risks to industrial water supplies in the lower North Saskatchewan River Basin (NSRB) of east-central Saskatchewan. Achieving this objective requires knowledge of both the regional consequences of global warming and the natural variability of the regional climate regime. We are reconstructing the natural variability of the past 300-900 years from tree rings, and stochastically downscaling these inferred water levels to weekly estimates. Tree-ring records have the advantage of greater record length than instrumental water and weather data. They also pre-date significant human interference with the global climate system. We will derive projections of future climate and runoff from the latest generation of Regional Climate Models that incorporate Land Surface Schemes for modeling surface hydrology. By assimilating hydroclimatic data for past centuries and future decades, we will determine how well climate models simulate internal (unforced) climatic variability and the extent to which model projected variability exceeds the natural variability in the paleoclimate record. Inter-annual to decadal variability and extreme hydrologic events present a greater challenge for managing water resources than incremental slow-onset changes in water yield. Using the PIEVC protocol from Engineers Canada as a climate risk assessment framework, we will collaborate with the industrial partners, Husky Energy and SaskPower, and with government regulators to identify significant climate risks to industrial water supplies in terms of their probability and consequences. This research directly benefits the industrial partners, and indirectly the Canadian energy industry, by providing data and knowledge to limit risks related to climate change and potential water scarcity.