The Magpie River ramping rate study (2000–2017) investigated the ecological effects of hydroelectric flow regulation on fish, invertebrates, and water quality in the Magpie and Batchawana rivers in the Algoma Region of Ontario. Conducted under a Fisheries and Oceans Canada–Brookfield Renewable partnership, the study employed a Before-After-Control-Impact (BACI) design to assess whether ramping rate restrictions at the Steephill Falls Waterpower Facility improved downstream conditions. Initial restrictions (2002–2005) were later removed, allowing unrestricted flow changes until 2017. In this dataset, monthly sampling from spring to fall included chlorophyll a and water chemistry at multiple sites to monitor productivity and detect irregularities. Analyses followed APHA standard methods, with chlorophyll a, pH, alkalinity, and conductivity processed at Fisheries and Oceans Canada, and major ions and nutrients at the Great Lakes Forestry Centre in Sault Ste. Marie, Ontario. Findings contribute to understanding flow management impacts on river ecosystems.