With 42 dams and 36 lakes connected by over 170 km of rivers, the Muskoka River Watershed is among the most complex in the Province. Management of the water in this watershed has evolved over 80 years to balance many competing needs, including, but not limited to, hydro electric power, transportation, tourism, environmental protection and shoreline landowners. Constrained by its backbone geology, management of water must adapt to a range of seasonal weather inputs plus an increasing frequency of extreme events driven by climate change. To fully understand the challenges of improving water management in this dynamic environment requires an appreciation of a broad range of information which is currently scattered in diverse sources. Without this appreciation there is a tendency to believe that changing the flow regime in the watershed is a simple matter. This paper synthesizes watershed information from disparate sources for use by the “Water Quantity Task Force” recommended by the Muskoka Watershed Advisory Group (MWAG) in its Interim Report1 and is also intended to enhance public understanding of the complexity of water management.