Anstruther is just west of Apsley and is in the Kawartha Highlands Provincial Park. Much of the shoreline is Crown Land, with many of the cottages being water access only. It is part of the Trent-Severn watershed, and eventually drains into the Mississagua River, and thence into Lower Buckhorn Lake, and from there into the Trent-Severn Waterway.
There are dams at the outlets of both Anstruther and the downstream Mississagua Lake that control the water level on Anstruther. Thus these lakes are reservoir lakes for the Trent-Severn Waterway.
The water levels on Anstruther can vary significantly. anstruther waterlevels