The Alton Grange is the site of the confluence of the East Credit River and Shaws Creek and is part of the Upper Credit River Watershed. The upper watershed includes all areas north of Inglewood. This section of the watershed lies on or above the Niagara Escarpment, where the main stem of the river and most of the tributaries remain in a relatively natural condition. Baseflow is maintained from springs and groundwater discharge, and water quality is generally good. Significant exceptions to this include Island Lake, the Credit River downstream of the Orangeville sewage treatment plant, and areas surrounding mineral extraction.
The upper watershed has cooler temperatures, longer snow cover, and more wind and rain than the other parts of the watershed. These conditions, in addition to the hummocky terrain, make it ideal for infiltrating precipitation and contributing to the groundwater supply.
The river and creek host and support a diversity of flora and fauna and provides critical spawning habitat for species such as Brook Trout which prefer the cold water provided by groundwater supply.