Hydropower is a low carbon energy source that provides reliable power, but imposes large, artificial sub-daily changes in flow that negatively impact ecological systems. Hydropower management faces the challenge of meeting economic and ecological objectives, neither of which can be fully optimized because of their Pareto nature. This study introduces an operational framework, called seasonal flexibility, as tool that aims to meet both sets of objectives. Economic objectives are met by allowing releases to deviate from inflows to generate power when it is most valuable. Ecological objectives are met by dynamically managing environmental flows to mitigate downstream impacts. Flexibility is defined by the magnitude (hourly IEO deviation) and frequency (energy price target hours) of these deviations and can be assigned seasonally. This study tests the impacts of seasonal flexibility using an optimization model of three hydropower facilities in the mainstem of the Connecticut River. A sensitivity analysis is conducted to quantify impacts to economic and ecological objectives with varying IEO deviation and energy price target parameters. A seasonal case study applies differing IEO deviation and energy price target parameters to seasons of ecological or economic importance. A Pareto frontier analysis characterizes the trade-offs among these flexible operation scenarios and identifies the most promising operations. The seasonal case study is also applied to an unimpacted flow regime to measure changes in economic and ecological objectives in a less altered system. Findings suggest that seasonal flexibility is a promising framework for the development of integrated, dynamic, and economically viable hydropower operations.