What is a Watershed?
A watershed is an area of land that drains its water, obtained from rainfall or snowmelt, into a single, specified body of water. A subwatershed is a smaller drainage area within the larger watershed. An example of a subwatershed would be an area of land that drains its water into a tributary creek or stream.
Conservation Halton is responsible for three major watersheds and 18 smaller watersheds located in the Halton Region. Each of these watersheds ultimately drains into Lake Ontario.
Grindstone Creek runs through the urban districts of Waterdown, Aldershot and Bayview as well as the largely rural western area of the Region of Halton. In total, the Grindstone Creek watershed comprises 99 square kilometres of land and supplies 14% of the natural water into Hamilton Harbour and Burlington Bay. A portion of the Grindstone Creek watershed lies within Carolinian forest zone. The Halton Region signifies the northern limit of the Carolinian forest in Southern Ontario. This forest region is home to a large diversity of plant and animal species, including some that are found nowhere else in Canada.
The Bronte Creek watershed is located at the Western end of Lake Ontario and covers portions of Wellington County, the City of Hamilton, Burlington, Oakville and Milton encompassing a total area of 304 square kilometres. This watershed contains mainly rural landscape and residents rely on groundwater sources for irrigation, drinking water and the watering of livestock. The main branch of Bronte Creek is 48km long and there are 12 primary subwatersheds that feed into the creek, each with its own unique streamflow and morphology.
Sixteen Mile Creek
Covering 357 square kilometres of land, the Sixteen Mile Creek watershed incorporates portions of Milton, Halton Hills, Oakville and Mississauga. The Niagara Escarpment crosses the northwest region of the watershed and Sixteen Mile Creek drains into Lake Ontario at the Town of Oakville. Three reservoirs are located within the watershed. These are used for flood control, low flow augmentation and recreation.
The North Shore watershed consists of 18 smaller watersheds located along the north shore of Lake Ontario crossing through Hamilton, Burlington, Oakville and portions of Mississauga. A typical small watershed draining into Lake Ontario is long and narrow. In the northern reaches of the watershed, the landscape tends to be rural but becomes more heavily developed toward the lake. Despite heavy development, the North Shore watershed contains some interesting natural features such as the Niagara Escarpment, Carolinian forest, old-growth forest and remnants of both prairie and oak savannah.
Watershed Report Card
Every five years, Conservation Halton produces a Watershed Report Card outlining our conservation achievements and providing an overall indication of the environmental health of the watersheds. To learn more about the Watershed Report Card, click here.