[2][3] It is the "final inland extension of Severn Sound"[4] on Lake Huron's Georgian Bay, and is "situated at the interface between the Saint Lawrence Lowlands and the Canadian Shield ".
[5] It exhibits geologically unique features at the junction of the Canadian Shield and southern Ontario limestone.
Wetland habitats in Matchedash Bay are varied, and include swamps, fens, cattail marshes, wet meadows and beaver ponds.
[5] Of the 170 species of birds that nest or breed in Matchedash Bay, some are provincially rare.
Urban growth in the surrounding areas is expected to negatively affect the site and its water quality.