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Source Water Protection

The Lakes Simcoe and Couchiching Source Protection Area

The large geography covered by the Lake Simcoe watershed is quite diverse in terms of population density, economy, and land use. Human characteristics across the watershed vary from the densely populated urban centers of Barrie, Aurora and Newmarket to the west and south, to the prominent agricultural communities in most other areas. Despite over 400,000 people living in the watershed, natural heritage features are the largest single land use in the watershed, including large tracks of wetlands and woodlands.

This Source Protection Area follows the boundaries of the Lake Simcoe Region Conservation Authority (LSRCA) and source protection work in the watershed is lead by the LSRCA. The LSRCA is the lead agency of the South Georgian Bay Lake Simcoe Source Protection Region and is a community based environmental agency that for more than 55 years has worked to protect natural resources in the Lake Simcoe watershed, in partnership with the watershed's municipalities.

For additional information on the Lake Simcoe Region Conservation Authority, please visit the LSRCA’s website at


Within the Lake Simcoe watershed, there are 22 municipal governments: four regions and counties, (Durham, Peel, Simcoe and York) and 18 local municipalities and separated cities. Population within the Lake Simcoe watershed during the 2001census was estimated 409,760 during the 2006 census. This represents an increase of 26,873 or 7% from the 2001 census. The most significant increases in population during the 5-year period occurred in the City of Barrie (24%) and the Towns of Newmarket (13%) and Aurora (18.6%). The Chippewas of Georgina Island is the only first nation reserve within the watershed. This reserve had a population of 353 during the 2006 census, at a density of 22 people per km2.

Watershed Information

Comprised of 18 subwatersheds, the Lake Simcoe watershed has a total drainage area of 3,324km2 (including Lake Simcoe).

Subwatershed Drainage Area Km2
Barrie Creeks 37.53
Beaver River 327.25
Black River 375.36
East Holland River 247.15
Georgina Creeks 49.33
Hawkestone Creek 47.84
Hewitt's Creek 17.52
Innisfil Creeks 107.15
Lovers Creek 59.95
Maskinonge River 63.47
Oro Creeks North 75.26
Oro Creeks South 57.39
Pefferlaw Brook 284.90
Ramara Creeks 143.51
Talbot River 70.51
Uxbridge Brook 161.34
West Holland River 351.93
Whites Creek 105.05
Lake Simcoe Watershed Islands 18.87
Lake Simcoe 722.78
Total 3,324.08

Over 51% of the watershed is natural heritage features, including swamps, woodlands, tall grass prairies and open water. The quality of the water cycling through the watershed is monitored at 12 Provincial Water Quality Monitoring Network stations and 14 Provincial Groundwater Monitoring Network wells. Phosphorus, a prevalent nutrient found in the surface waters, has been detrimental to the aquatic systems within the watershed, as it is furthering the process of eutrophication in the lake. For the most part, groundwater samples have shown to be consistently below the Ontario Drinking Water Standards, Objectives and Guidelines. The condition of the fish and benthic communities living in the watercourses has also been a good indicator of water quality within the watershed. The Lake Simcoe watershed supports both cold- and warmwater fish species. Samples taken between 2005 and 2007 showed that out of 168 samples, 62 (or 37%) were impaired. Benthic sampling from 2004-2007 had results of 50 (or 38%) of the sites being impaired, indicating some of the aquatic systems appear to be under stress. Over 400,000 people live in the 4 regions/counties and 18 local municipalities/cities that are in the watershed. The Chippewas of Georgina Island, with a population over 300, are the only First Nations community within the watershed.

Wetlands, including swamps, bogs and marsh occupy approximately 13% of the Lake Simcoe watershed. They are scattered throughout the watershed, with the highest concentrations to the northeast and to the south of Lake Simcoe in Black, Holland, Pefferlaw, and Beaver subwatersheds. The watershed is noted for having one of the highest concentrations of large wetlands off the Canadian Shield, in southern Ontario.

Within the Lake Simcoe area there are 31 drinking water systems, serviced by 84 municipal wells and 7 surface water intakes. In the Lake Simcoe Watershed, groundwater is used for municipal water supply, agricultural use, industrial use, golf course irrigation and private water supplies. Groundwater is the primary source of potable water. With the exception of Sutton, Keswick, Alcona, Lagoon City and Beaver, which use surface water from Lake Simcoe; and Newmarket and Aurora, which rely on groundwater supplemented with surface water from Lake Ontario, all communities3 in the watershed depend on either private or municipal groundwater supplies.

Geographic Information

The Lake Simcoe watershed is located within six regional- scale physiographic regions. These regions are the Simcoe Lowlands, Simcoe Uplands, Peterborough drumlin field, Schomberg clay plain, Oak Ridges Moraine and the Carden Plain. The Oak Ridges Moraine (ORM) is a significant hydrogeologic feature located in the Lake Simcoe watershed. The ORM extends approximately 160 km eastward from Niagara Escarpment to Trenton forming four sediment wedges approximately 30-40 km long and up to 20 km wide.

The geology of the Lake Simcoe basin can generally be described as sedimentary bedrock units overlain by unconsolidated overburden materials that have been deposited and modified by glacial, fluvial and lacustrine processes.

Overall, 1,724 km2 of the Lake Simcoe watershed is classified as natural heritage features (NHF), or approximately 52% of the total area. The percentage of natural vegetative cover within each subwatershed varies from as low as 17% within the Barrie subwatershed, to 57% within the Hawkestone Creek subwatershed; Georgina Island has the highest coverage at 92%. Woodland cover percentage is lowest in the Beaver River subwatershed (8%) and highest on one of the Lake Simcoe Islands (Fox Island) with approximately 67%. Woodlands reduce the speed of overland water flow and erosion, increase evapotranspiration, intercept rainfall, and increase water infiltration to shallow groundwater areas.