While there are no clear boundaries, Crothers' Woods is generally thought to include both sides of the valley that extends from Pottery Road and the Bayview Avenue extension in the south and west to the Millwood Road bridge in the east. Further east, good quality forest exists on the north side of the valley for another 1.2 km to the western edge of E.T. Seton Park.
The land in this part of the valley is owned by the TRCA and managed by the city of Toronto's Parks and Forestry Department.
Prior to European colonisation, this area of the valley was heavily wooded. The area remained relatively untouched until 1787 when this area was bought from the Mississauga natives as part of the Toronto Purchase. After the establishment of York in 1793, land grants were made for much of the land north of the city including the Don Valley. In the 1800s, the Don River was exploited for its capacity to support water driven mills. At least two mills were constructed in this part of the valley. They were eventually purchased by the Taylor family who owned the Don Valley Brick Works.
Due to urban expansion, the city constructed the North Toronto Sewage Treatment Plant in 1929. This handles effluent from local areas including Leaside and North Toronto.
Domtar operated a plant that produced polyresins on the south side of the valley. This operated until the 1980s when it was shut down. Subsequently the TRCA purchased the land and demolished the building. This area was cleaned up and contaminated soil removed.
On the north side of the valley, the land where a former brick making operation called Sun Valley Ltd. was used as an industrial landfill. This was used mostly for brick and ash waste from nearby industry. It was shutdown in the 1980s. The dump was capped with clean fill and now is marked by a large meadow covered with invasive grasses and plants. It is currently undergoing natural restoration efforts. In particular it has become the Don Valley site for Trees Across Toronto, a city wide tree planting program.
Animals typical of an urban forest can be seen here. Black-crowned Night Herons have been spotted near the river and at ponds within Crothers' Woods. Red-tailed Hawks are also frequent visitors and can be seen hovering over the woods. Recently White-tailed Deer have been spotted in the woods and it appears they are becoming permanent residents.
Due to the steep walls and the extensive gullies that exist through this part of the valley, Crothers' Woods attracted the attention of many user groups over the years. A trail network which was begun by motorcyclists in the 1960s was subsequently adopted by cyclists in the 1980s with the advent of the mountain bike. Cycling usage grew steadily over the next decade, corresponding with the North American popularity of the sport, and the trails were also enjoyed by trail runners, dog-walkers, bird-watchers, and hikers. By the early 1990s, some of the trails had become degraded through overuse. At that time, initial efforts were made by the Parks Department to control the environmental damage by blocking off badly eroded trails. However, this activity was postponed after the Metro amalgamation in 1998.
In 2004, the city again became involved at the behest of local groups such as the Task Force to Bring Back the Don. Rather than try to limit use, the city adopted a proactive approach and decided to work with all stakeholders and user groups to repair and improve the trail system. For the short term, they brought in consultants from the International Mountain Bicycling Association and put on trail building workshops. These workshops have taught skills necessary to create shared sustainable trails and have resulted in a marked improvement in the quality of the trail system. While the cycling community has supported this program with volunteer labour, some environmentalists have been less than sanguine about the continued cycling activity in Crother's Woods.
For the longer term, the city commissioned a management plan in 2006 on Crothers' Woods to come up with guidelines on how to best manage the trails and alleviate the longstanding friction between the various stakeholders and user groups.
As the single largest user group of the trails in Crothers Woods, cyclists have recently organized in order to better deal with the city staff and other smaller stakeholder groups. In 2004, a group called the Don Valley Trails Users Club was formed by cyclists, and was intended to serve as an umbrella organization representing all trail users. In 2007, the DVTUC was superseded by a new organization called the Toronto Off Road Bicycling Group, with a stronger mandate to represent cyclists.