Muskoka consists of four primary watersheds and seventeen secondary watersheds.
There are four primary watersheds in Muskoka. The Black and Severn River Watersheds flow through the Severn River to Georgian Bay and the Muskoka River and Georgian Bay Watersheds flow directly to Georgian Bay through the Moon, Musquash or other smaller rivers in the Township of Georgian Bay.
The headwaters for the Muskoka River are found in Algonquin Park, and flow southwesterly for a distance of about 210 km to release into Lake Muskoka before it continues into Georgian Bay through the Moon and Musquash Rivers.
The Muskoka River Watershed is the largest watershed in Muskoka. The watershed:
The Muskoka River Watershed is divided into three secondary subwatersheds: the North and South Branches, and the Lower Muskoka subwatershed. It is further divided into eight tertiary watersheds.
The North and South Branches comprise roughly two-thirds of the eastern part of The District Municipality of Muskoka. Beginning in the highlands of Algonquin Park they flow southwesterly, uniting in Bracebridge. They then continue to flow into Lake Muskoka.
The Lower Muskoka subwatershed receives the inflow from the North and South Branches as well as Lake Joseph, Lake Rosseau, and Gull and Silver Lakes in Gravenhurst.
The Black River begins in the Haliburton Highlands and flows southwest passing through the southeast corner of Muskoka. The portion of the watershed in Muskoka is approximately 360 km2. Vankoughnet is the only community in Muskoka in the Black River Watershed.
The Severn River is the lower end of the Trent-Severn Historic Waterway, managed by Parks Canada. It flows from Lake Simcoe and Lake Couchiching to Georgian Bay at Port Severn. The portion of this watershed in Muskoka is approximately 357 km2.
The subwatersheds in the Severn River Watershed includes Kahshe Lake, which flows directly into Sparrow Lake. Morrison Lake, Six Mile Lake and Gloucester Pool all flow directly into the Severn River just upstream of the mouth at Port Severn.
Georgian Bay is a large bay in Lake Huron and receives all the water from the watersheds in Muskoka. Besides the major watersheds identified on this page, there are several smaller watersheds that flow directly into Georgian Bay from the western portion of Muskoka.
The land area represented by these smaller watersheds is approximately 900 km2.
The subwatersheds that make up the Georgian Bay Watershed in Muskoka include Brotherson/Nine Mile Lake in the southern portion of the Township of Muskoka Lakes, and the Moon, Musquash and Go Home Rivers in the Township of Georgian Bay.