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Source Water Protection

Severn Sound Source Protection Area

The large geography covered by the Severn Sound watershed is quite diverse in terms of population density, economy, and land use. Human characteristics across the watershed vary from the built up urban centres found in the larger municipalities to the beautiful waterfront communities located along the coastline of Georgian Bay. Despite almost 70,000 people living in the watershed, natural vegetative features are the largest single land use in the watershed (55%), followed by agricultural practices.

This Source Protection Area is administered by the Severn Sound Environmental Association. It is a local association that reflects the community’s recognition of the necessity of working together to restore, protect and sustain a healthy environment for future generations. In 1985 Severn Sound was listed as one of 43 Areas of Concern with respect to water pollution by the International Joint Commission (IJC), a joint Canadian/U.S. organization who oversees cross-boundary issues affecting the Great Lakes. In 1997 the Severn Sound Environmental Association (SSEA) was formed with the goal of overseeing the delisting of Severn Sound as an ‘Area of Concern’ and to effect the transition from the Remedial Action Plan program to a locally sustained environmental program.

Members of the Severn Sound Environmental Association include Environment Canada, the Ontario Ministry of the Environment, the Towns of Midland and Penetanguishene, the Townships of Tay, Tiny, Oro-Medonte, Severn, Georgian Bay and Springwater, and the City of Orillia. Thanks to the efforts of all stakeholders, Severn Sound was removed from the International Joint Commission’s list of Areas of Concern in January 2003. You can learn more about the SSEA at

Population Information

The Severn Sound Watershed lies within two upper tier municipalities – County of Simcoe and District of Muskoka; and nine lower tier municipalities. Population of these municipalities is presented in. Population growth within the Severn Sound watershed is anticipated to continue in the range of 40-60% between 2001 and 2016. In general, urban areas are restricted to the larger municipalities within the watershed, while many of the settlement areas are waterfront communities. Some of these communities include; Orillia, Midland, Penetanguishene, Victoria Harbour and Port McNicoll. Although originally settlement in these areas occurred as a result of ease of transportation on waterways, current day development is due to a desire to live or vacation near a water body.

Watershed Information

The Severn Sound watershed has a total drainage area of about 1,380 km2, a maximum length of about 43 km in a northwest-southeast direction and a maximum width of about 46 km in a northeast-southwest direction. The Severn Sound watershed has been divided into 19 subwatersheds or hydrological units (excluding Severn Sound islands).

Subwatershed Drainage Area Km2
North River 318.74
Coldwater River 191.40
Sturgeon River 98.30
Hog Creek 60
Wye River 208.15
Port Severn and Matchedash Bay North 19.71
Waubaushene and Matchedash Bay South 19.08
Lafotaine Creek 54.74
Tiny Coastal North East 46.46
Copeland Creek 23.56
Penetang Bay West 24.15
Penetanguishene and Tay Point 25
Tiny Coastal Area West Central 21.49
Tiny Coastal Area South 46.51
Tiny Coastal Area North West 37.85
Midland Area 24.16
Tiffin Basin and Port McNicoll Area 16.10
Victoria Harbour Area 16.52
Honey Harbour to Port Severn 68.40
Severn Sound Islands 59.53
Total 1,379.87

The North River is the largest drainage system in the study area. It rises in a hilly plateau to the north of Bass Lake. The river then flows in a south-north direction until a point approximately 2 km north of Hampshire Mills, where it changes its course into a northwesterly direction until it reaches Lovering. From Lovering, the river flows in a southwesterly direction to its outlet into Matchedash Bay. The North River has three major tributaries: Purbrook, Bear and Silver Creeks; 25 second order tributaries, and numerous lower order tributaries.The streams occupy the flat-floored valleys within the watershed and many of them appear to be fed largely by springs along the valley sides.

Geographic Information

The Severn Sound Watershed is located within three (3) regional-scale physiographic regions as defined by Chapman and Putnam (1984): Carden plain, Simcoe uplands and the Georgian Bay fringe (Chapman and Putnam 1984).

Overall, approximately 760km2 of the Severn Sound watershed is considered natural vegetative cover, or roughly 55% of the total area. The percentage of natural vegetation within each subwatershed varies from as low as 36% within the Midland Area subwatershed, to just over 86% in Tiny Coastal North East; Christian Island had the highest coverage at 98%. Wetlands occupy 3.8% of the Severn Sound watershed, of which some have been identified as Provincially Significant Wetlands.

Woodland cover percentage is lowest in the Wye River subwatershed (34%) and highest in Tiny Coastal Area North East subwatershed (not including the Severn sound Islands) with approximately 84%. In addition, there are 16 Areas of Natural and Scientific Interest (ANSI) in the watershed. One of them, the Penetanguishine Harbour ANSI, is an Earth Science ANSI. These are areas identified by the MNR as having provincially or regionally significant representative geological features. The other 15 ANSIs are Life Science – areas identified as having provincially or regionally significant ecological features. While the Penetanguishine Harbour occupies 108 ha, the Life Science ANSIs occupy 6,168 ha of the watershed area.

The geology of the Severn Sound watershed can be generally described as being comprised of unconsolidated overburden, deposited during the Quaternary Period, overlying Paleozoic and Precambrian bedrock. Some bedrock outcropping occurs in the northern portion of the study area.