Lake Winnipeg usually experiences ice cover during December to May (South Basin)/ June (North Basin). This dataset are water quality data collected in the South Basin of Lake Winnipeg during the winter of 2024, for the Freshwater Lake Winnipeg project. The bottom part (10cm) of ice-core samples were melted into water, and the nutrient concentrations were measured. The objectives of the winter limnology study in Lake Winnipeg is to (1) understand the year-round nutrient dynamics in the lake; (2) explore the relationship between ice phenology/winter limnology and following summer algal bloom.