The Don River is one of two rivers bounding the original settled area of Toronto along the shore of Lake Ontario, the other being the Humber River to the west. The Don is actually two rivers, the eastern and western branches, that meet about 7 km north of Lake Ontario while flowing southward into the lake. The area below the confluence is known as the lower Don, and the areas above as the upper Don. The Don is also joined at the confluence by a third major branch, Taylor Creek, and a smaller creek, Wilket Creek.
The eastern arm of the rivers starts near the Oak Ridges Moraine just to the west of Yonge Street, flowing south-eastward through ravine forests in Richmond Hill, Thornhill, east of Willowdale and Don Mills. A second branch of the eastern Don, known as German Mills Creek, parallels the main eastern branch and joins it at Steeles Avenue, the northern boundary of Toronto.
The western half starts near the area of Maple, flowing south-west through the suburban industrial belt of Concord (Vaughan), a reservoir, and then through the York Mills and Leaside areas before joining the eastern half. Taylor Creek runs almost due west into Scarborough.
The mouth of the Don was relocated by a land expansion of about 3 km² to make room for an industrial area. This moved the confluence further from the lake, to 7km from about 6km before the expansion, as well as moving it some 500m to the west. Unlike the mouth of the Humber which is located in a recreational area and navigatable, the mouth of the Don is located in a heavily industrialized area, spanned by a number of low bridges which make it impassible. In late 2000 several plans were being drawn up to redevelop the area, including relocating the mouth closer to its original location, and developing a canal system around the area.
The Don had been heavily developed in the earlier portions of the 20th century, with several major factories, two major rail lines and then a major freeway, the Don Valley Parkway, being built in the river valley. The last of the industrial plants, Domtar Polyresins, closed in the 1980s and has since been reused as the Toronto Police Force K-9 training site. The only remaining industrial use on urban portions of the river is the North Toronto Sewage Treatment, who's use is currently under review.
Much of Taylor Creek the southern portion of the western branch are surrounded by parkland. In more recent years the retreat of the industrial plants and rail infrastructure has freed up room which is now being turned into bicycling trails, which now extend from the shore of Lake Ontario northward in several directions to provide some 30km of off-road paved trails. While Toronto is fairly flat in general, local cyclists have developed a number of technically challenging singletrack trails throughout the area, following the main trails.
Tributaries: