The advent of variable renewable energy has created an urgent need for demand-based generation and storage. At present, with batteries still awaiting a major technological breakthrough, hydropower combined with pumped storage is suggested as a key response to demand variability. Even overlooking the technical demands, developing this potential resource in a sustainable way presents formidable challenges. While sustainability is a concern, the vulnerability of the resource to changing climatic conditions poses a major threat. The present study proposes five modelling approaches (and/or frameworks) as a foundation to a systems approach to hydropower and shows how these tools address the key challenges. Overall, the research addresses the current demand for dispatchable generation particularly in Ontario and proposes several alternatives including their sustainability assessment. Of the five models, the first two explore a variety of remuneration structures for pumped storage in the context of Ontario. The work begins with an optimization approach that evaluates the wholesale market for optimal profit. The tradeoff between hydropower and ecological targets is explored using a Constraint Method. The results are compared with models based on contracted price and an integrated valuation approach that accounts for the socioeconomic attributes of storage using representative applications. While the first two approaches concentrate on the project economies, the third model evaluates the potential for increased hydroelectric generation and assesses its vulnerability scenarios of climate change. A 1D simulation model of the existing power system at Niagara is used to evaluate a variety of innovative operating plans. One such scenario includes a revised approach to daily operation with use of additional storage during the night and timed release during peak demand hours. The final section seeks to improve the existing frameworks for sustainability assessment and then to use these improved metrics to evaluate various ...