Natural History of Credit River Watershed

How do we know what the Credit River Valley looked like before settlement and the invention of photography and video cameras?

Land surveyors recorded the most common tree species along the boundaries of each survey lot. Details of the composition of the forests were also recorded. Using this information and new technologies we are able to create a general picture of what types of communities were in the watershed before it was settled.

A Landscape Picture

Most of the watershed was dominated by maple deciduous forest mixed with pine coniferous forests and the occasional wetland. There were also beech, basswood, oak and elm in the upper watershed.

The lower watershed was more diverse. Located in the Carolinian Deciduous Forest zone (the upper watershed is located in the Great Lakes - St. Lawrence zone) these younger forests were rooted in sandy soils. These soils were exposed when Lake Ontario (once Lake Iroquois) receded. The hill on Dundas Road near Mavis Road in Mississauga was once the shoreline of Lake Iroquois and contained maple, oak, hickory and pine. There were also areas of swamp, savannah and prairie.

What is left?

Many of the natural areas have been lost to industrialization and population growth however some areas do still exist. Most of these areas are located in the upper watershed.

The Niagara Escarpment extends from Niagara Falls to Tobermory. The Bruce Trail follows the Niagara Escarpment through Halton Hills and Caledon . It has been named a World Biosphere Reserve by the United Nations Educational, Scientific and Cultural Organization because of its significant ecosystems. Click here to connect with the Niagara Escarpment Commission.

The Oak Ridges Moraine is found in the upper east area of the Credit River watershed. It is one of 9 moraines influencing watershed. Like all moraines, the Oak Ridges Moraine acts as a large sponge absorbing rain and snow and delivering this water to underground aquifers. These aquifers store, filter and slowly release water into rivers flowing into Lake Ontario and provide fresh, clean water to wells. The Moraine also protects the rivers, roads and properties in the Greater Toronto Area from damaging storm water and floods.


To find out about more areas of environmental significance in the watershed click here.