Modelling phosphorus dynamics in multi-branch river systems: A study of the Black River, Lake Simcoe, Ontario, Canada

► Demonstrate application of a new multibranch INCA-P model. ► Assess the changes of stream TP concentrations in likely future conditions. ► Evaluate the effectiveness of potential future remedial actions. ► Scenario results show the difficulty in achieving large-scale P reductions in Simcoe Lake from the watershed. ► P reductions to Lake Simcoe will require long-term management changes.