A tool for modeling the winter oxygen depletion rate in arctic lakes

Many arctic lakes freeze completely in winter. The few that retain unfrozen water for the entire winter period serve as overwintering fish habitat. In addition to serving as fish habitat, water in arctic lakes is needed for industrial and domestic use. Permits for water extraction seek to maximize water use without impacting dissolved oxygen (DO) levels and endangering fish habitat. The relationship between lake volume, winter DO budget, and extraction of water through pumping has historically not been well understood. A management model that could estimate end-of-winter DO would improve our understanding of the potential impacts of different management strategies. Using under-ice DO measurements (November to April) taken from two natural lakes and one flooded gravel mine on the North Slope of Alaska, a physically based model was developed to predict end-of-winter DO concentration, water-column DO profiles, and winter oxygen depletion rate in arctic lakes during periods of ice cover. Comparisons between the measured and model-predicted oxygen profiles in the three study lakes suggest that the depth-based DO modeling tool presented herein can be used to adequately predict the amount of DO available in arctic lakes throughout winter.