The geographic area covered by the Miramichi Watershed Management Committee mandate is that of the Miramichi Recreational Fishery Area (area # 3 in the provincial angling summary).  It includes all waters draining into Miramichi Bay north of Point Escuminac as well as all lakes and streams draining into Tabusintac Bay. The principal river systems within the Miramichi Recreational Fishery Area are the Southwest Miramichi, the Northwest Miramichi, the Tabusintac and the Bartibog. Smaller rivers that are also within the drainage area include the Barnaby, the Northwest Millstream, the Burnt Church, and the Black.

The large Miramichi River watershed can be further divided into its two major sub-basins; the Northwest Miramichi River system and the Southwest Miramichi River systems. The Northwest Miramichi system has a drainage area of 3,950 km2 and encompasses approximately one third of the Miramichi Watershed (Blousfield 1955). It is made up of two principal rivers which share a common estuary, the Little Southwest Miramichi and the Northwest Miramichi which drain areas of 1,342 km2 and 2,078 km2, respectively. By comparison the Southwest Miramichi system has a drainage area of 7,700 km2 and encompasses approximately two thirds of the Miramichi watershed (Blousfield 1955). It is also made up of two river systems which share a common estuary, the Southwest Miramichi River and the Renous River.