Canada’s freshwater resources are increasingly under pressure from climate change and human water consumption, threatening aquatic ecosystems and water security. Ecological Maintenance Flows (EMFs) are a regulatory tool to prescribe minimum flows to sustain ecosystem functions including fish spawning, and wetland connectivity. However, EMFs in Canada often rely on simple hydrological thresholds, such as fixed percentages of mean or median annual flows, which do not reflect natural flow regimes or seasonal variability. With climate change increasing the frequency and severity of hydrologic extremes, there is a need for EMF approaches that are climate-resilient and that better reflect natural flow regimes. The objective of this study is to assess and improve methodologies for establishing EMFs in Canada. The core study site is a key drinking water supply reservoir in Halifax, Nova Scotia, comprising a mid-sized lake, an associated dam, and a downstream tributary. Hydrologically similar unregulated gauged lake-river systems will first be analyzed to identify natural streamflow patterns typical of this region. Then, a hydrological model of the drinking water reservoir and its contributing watershed will be developed using HEC-HMS and calibrated using historical lake stage and dam outflow data. The calibrated model will be used to simulate and evaluate multiple EMF selection approaches (hydrological, hydraulic, habitat-based, and holistic) under current and projected future climate scenarios. In this presentation we will present results from our initial analysis of hydrologically similar watersheds, and how the current EMF management approach for this watershed compares to these findings.