The Grindstone Creek headwaters wetland complex is the source water for the Grindstone Creek and the Medad Valley - including Lake Medad. This wetland complex acts as the water purifier for waters entering many Medad Valley springs, and helps purify the water that eventually makes it's way to lake Ontario. The Grindstone creek headwaters wetland complex is a key contributor to fresh water for the western basin of lake Ontario.This complex of wetlands has been formally recognized by the MNR to be of provincial significance.
MNR identified that this wetland complex serves a number of important ecological functions, including the following:
Water storage function that regulates the hydro-period, flow rate and thermal condition in the wetlands;
In conjunction with the surrounding natural landscape, serves as a local northsouth corridor between larger forested areas. At the broader landscape level, serves as a southwest-northeast corridor for wildlife movement across the top of the Mount Nemo plateau;
Provides connections between the Medad Valley ANSI, the provincially significant Lake Medad Valley Wetland Complex and the Mount Nemo Escarpment ANSI;
Supports five significant species including a breeding population of the nationally and provincially threatened Jefferson Salamander, the provincially endangered Butternut tree and three locally rare plant species;
Provides breeding habitat for amphibian populations including Jefferson Salamander, Spotted Salamander, Spring Peeper, Wood Frog, Gray Treefrog, Bullfrog, Green Frog, Leopard Frog, American Toad and Eastern Newt. Wood Duck breeds in the wetland swamps;
In conjunction with the surrounding upland forests, provides habitat for area sensitive forest birds, including Wood Duck, Pileated Woodpecker and Ovenbird.
The complex contains 15 wetlands which make up a total area of 17.6 ha. They consist of 53% swamps and 47% marshes, and include 24 wetland vegetation communities. The wetland complex lies within three headwater tributaries of Grindstone Creek and a headwater tributary of Bronte Creek.