Watershed Characteristics

Canada has five Primary Watersheds: The Pacific The Arctic Hudson Bay The Atlantic, and A small area that flows to the Gulf of Mexico …. As mentioned in Water and Watersheds

…23 Secondary Watersheds, including: The Mackenzie; The Yukon; The Peace-Athabaska; The Nelson; and, The Great Lakes Basin; …

… and hundreds of tertiary and quaternary watersheds within the secondary watersheds, such as in the Great Lakes Basin

In Ontario, most of these watersheds, such as the Grand and the Credit, are managed by one of Ontario’s 36 conservation authorities, in partnership with other agencies.

How can we both appreciate and contrast our watersheds? Given the significant variety of these watersheds, to the compact Credit - from the sprawling Grand

The simple answer is that watersheds can be best described and contrasted through their Characteristics. Characteristics tend to describe base-line conditions, including climate, slope, geology, and soils, as well as the state of pre-settlement bio-diversity.

Characteristics address questions such as: Do underlying geological conditions - sand, soil, Canadian Shield – retain water, allow it to infiltrate into the ground, or shed it quickly? Will precipitation fall as rain or snow, due to climate & elevation? Has the area’s biodiversity been maintained, or has it been impacted by development? Does the area have a cold, cool, or warm-water fishery?

Watershed Characteristics include: Watershed Size; Climate and Elevation; Geology, Slope, & Soils; Hydrology; and, Vegetation & Biodiversity

To better understand Watershed Characteristics, think about the difference between the Mackenzie … which is about half the size of the “i” in Mackenzie on its map. and the Credit,

The Mackenzie is a broad, gently-sloped, slow-moving river in a Northern climate that receives just over 400 mm of precipitation per year.

Vegetation is relatively sparse due to thin soils and the climate, with permafrost underlying 75% of the watershed.

In spite of these factors, extensive wetlands and other natural areas host amazing biodiversity, including many species of fish, birds, and iconic mammals such as bear, caribou, and wolves.

the Credit’s much smaller volume of water flows more quickly, due to a steeper slope, with fewer wetlands on top of both the Niagara Escarpment and the Oak Ridges Moraine, in a moderate climate with over 850 mm of precipitation - more than double that of the Mackenzie. In contrast,

Vegetation is much thicker than in the Mackenzie, and includes hardwood forests, but is limited in spots due to thin soil cover over both the Niagara Escarpment and glacial deposits of sand, gravel, and clay.

Finally, biodiversity has been far more impacted by development in the Credit than in the Mackenzie, especially in the southern third of the watershed, which is highly urban, although extensive efforts upstream have maintained a cold-water fishery.

Regardless of where you live, your watershed is best understood through an appreciation of its key characteristics.

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