Huron-Erie Corridor: On the role of Lake St. Clair in attenuating phosphorus loads

Session: Great Lakes Tributaries: Connecting Land and Lakes (3)

Serghei Bocaniov, University of Waterloo, [email protected]
Philippe Van Cappellen, University of Waterloo, [email protected]
Donald Scavia, University of Michigan, [email protected]

Abstract

The new 2012 Great Lakes Water Quality Agreement (GLWQA) demands more robust estimates of total load of phosphorus (P) to Lake Erie and scientifically-based understanding whether a 40% reduction in total P load can be achieved by corresponding decreases in each of its sub-watersheds. While sub-watersheds that feed directly into the lake constitute a greater portion of Lake Erie’s watershed, about 20% feed indirectly. Among the latter are those that discharge indirectly via Lake St. Clair, which due to its size has the ability to modify the nutrient fluxes, and therefore creating an uncertainty in the relationship between sub-watershed reductions and the amount ultimately contributing to Lake Erie. Lake St Clair has a large watershed (14,000 km2) with three significant tributaries, Thames, Sydenham and Clinton rivers. To facilitate the improved understanding between reductions in P in these three largest tributaries to Lake St. Clair and load that contributes to Lake Erie, we applied a three-dimensional lake model to Lake St. Clair to construct the P load-response relationships. Their results will be presented and discussed in this presentation.