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Source Water Protection

Nottawasaga Valley Source Protection Area

The Nottawasaga Valley Source Water Protection (SWP) area is located in the south-west quarter of the South Georgian Bay-Lake Simcoe (SGBLS) SWP region and is bounded to the south by the Humber and Credit River watersheds and the east by the numerous small streams which drain into Lake Simcoe. The Niagara Escarpment forms part of the western boundary, separating the Nottawasaga from the Grand, Grey Sauble and Saugeen watersheds.

This Source Protection Area follows the boundaries of the Nottawasaga Valley Conservation Authority (NVCA) and source water work is administered by staff at the Conservation Authority. It is a local, watershed management agency that delivers services and programs that protect and manage water and other natural resources in partnership with government, landowners and other organizations.

The activities of Conservation Authorities may be described in terms of environmental protection, water resource management and lifelong learning and recreation. NVCA’s vision is “Conserving our Healthy Waters”, and in cooperation with our member municipalities and residents, we strive to achieve our mission of “Working together to value, protect, enhance and restore our watershed resources for a healthy, sustainable future". You can learn more about the NVCA at


The large geography covered by the Nottawasaga Valley watershed is quite diverse in terms of population density, economy, and land use. Human characteristics across the watershed vary from the more densely populated urban centers such as Collingwood and Wasaga Beach along the shoreline of Georgian Bay, to the prominent agricultural communities in most other areas. Despite over 181,000 people living in the watershed, agricultural activities are the largest single land use in the watershed, including large areas of hay/pastures and row crops.

The Nottawasaga Valley Watershed lies within the Counties of Simcoe (74%), Dufferin (22%), and Grey (4%). The watershed is bounded to the south by the Humber and Credit River Watersheds. The Niagara Escarpment forms part of the western boundary, separating the Nottawasaga from the Grand and Saugeen Watersheds. On the east, the Nottawasaga Watershed is bounded by the numerous streams which drain into Lake Simcoe.

Watershed Information

The Nottawasaga River is approximately 122 km in length along its main channel and has a drainage area of 3,147 km2. The main branch of the river’s source is in the till moraines of Amaranth Township at an elevation of almost 490 meters. The Nottawasaga River has a total drop of 310 meters to its outlet into Georgian Bay and has an average gradient of 2.6 meters per km. However, in the upper reaches of the river, the gradient is as much as 19 meters per km. The Nottawasaga Valley has 9 subwatersheds (Figure 2-2), the largest subwatershed being the Lower Nottawasaga River at 455 km2, and the smallest being the Blue Mountains subwatershed at 220 km2. The Blue Mountains subwatershed, does not flow into the Nottawasaga River, but consists of a number of smaller rivers that drain directly into Georgian Bay. An unusual characteristic of the Nottawasaga Valley watershed is its virtual lack of natural lakes.

Subwatershed Drainage Area Km2
Upper Nottawasaga River 338.136
Lower Nottawasaga River 455.43
Blue Mountains 220.72
Innisfil Creek 490.03
Boyne River 239.94
Mad River 451.94
Willow Creek 306.53
Middle Nottawasauga River 296.78
Total 3,146.66

Within the Nottawasaga Valley area there are 35 drinking water systems, serviced by 107 municipal wells and 1 surface water intake at Collingwood.

Geographic Information

The Nottawasaga Valley Watershed is located within four (4) regional-scale physiographic regions as defined by Chapman and Putnam (1984). These regions include the Horseshoe Moraines, Peterborough Drumlin Field, Simcoe Lowlands and the Simcoe Uplands.

Overall, 1,086 km2 of the Nottawasaga Valley watershed is considered natural vegetative cover, or approximately 34.5% of the total area. The percentage of natural vegetative cover within each subwatershed varies from as low as 21% in the Innisfil Creek subwatershed, to the highest in the Willow Creek subwatershed, with almost 47%.

Wetlands occupy approximately 12% of the Nottawasaga Valley watershed with large expanses of wetlands being found on poorly drained lands on the Dundalk Plain above the Niagara Escarpment and the Lake Simcoe Lowlands in the central portion of the watershed. Long, narrow wetlands on the other hand, are often found along river valleys as well as along Georgian Bay shoreline. A number of wetland groupings within the watershed have been identified as provincially significant by the Ontario Ministry of Natural Resources.

Forest cover in the Nottawasaga Valley watershed is generally healthy and covers just over 22.5% of the watershed (34% if woody wetlands are included). Significant forest cover is generally found on lands that are unsuitable for agriculture. Areas with highly productive farmland, such as the Innisfil Creek Subwatershed, have relatively low forest cover.

The geology of the Nottawasaga Valley basin is generally comprised of unconsolidated overburden, deposited during the Quaternary Period, overlying Paleozoic and Precambrian bedrock.