| The overall goal of this study was to quantify the major and minor phosphorus (P) sources to and losses from the Lake of the Woods (LoW), summarized as a nutrient budget. Additionally, due to the great spatial and seasonal variability in nutrients and algal productivity in the LoW, P sources to sheltered embayments with unique water quality were quantified and compared to the overall lake P budget. The LoW nutrient budget shows that currently, there is only a small total P contribution from shoreline developments (6 t; ∼1%), relative to the large P loads from atmospheric deposition (95+/-55 t; 13%) and the primary tributary, the Rainy River (568+/-155 t; 75%). Overall, the annual gross TP load to the LoW was between 714 to 813 t with 45 to 66% of the gross TP load retained within the lake. The nutrient budget for the Rainy River catchment revealed that contributions from point sources along the river constitute the largest anthropogenic total P source to the LoW rather than shoreline development By comparison, shoreline development in Clearwater Bay and Poplar Bay, isolated bays in the northwest region of the lake, made up more than 1/3 of the bay TP budgets. The lakeshore capacity model predicted a whole-lake TP concentration within the range of measured TP concentrations in the LoW. However, it is more rational that this model is considered only for the main channel of the LoW, and isolated areas of the lake are modeled as separate basins.;Keywords: Lake of the Woods, Rainy River, Sheltered embayments, Phosphorus, Nutrient budget, Shoreline development, Hypolimnetic oxygen, Modelling... |
