| Northwest Branch Saint John River | |
| Subdivision Type1: | Countries |
| Subdivision Name1: | Canada, United States |
| Subdivision Type2: | States |
| Subdivision Name2: | Quebec, Maine |
| Subdivision Type3: | Cities |
| Subdivision Name3: | Lac-Frontière, Quebec |
| Source1 Location: | Frontier Lake (Quebec-Maine), municipality of Lac-Frontière, Quebec, Montmagny Regional County Municipality, Quebec |
| Source1 Coordinates: | 46.7014°N -69.9986°W |
| Mouth Location: | Saint John River, Somerset County, Maine, Maine, United States |
| Mouth Coordinates: | 46.5633°N -69.8856°W |
| Length: | about |
| Tributaries Left: | (from the mouth) Oak Brook, Bean Brook, discharge of Beaver Pond. |
| Tributaries Right: | (from the mouth) Eastman Brook, Daaquam River, Otter Brook (or "rivière à la Loutre" in Quebec). |
The Northwest Branch Saint John River (French: Décharge du Lac Frontière) is a 15.5adj=midNaNadj=mid[1] river primarily in Aroostook County, Maine, USA. Its origin (46.7012°N -69.9987°W) is Frontier Lake (Quebec-Maine) in Quebec, Canada. After crossing the Canada–United States border, the Northwest Branch runs south close to the border until it picks up its tributary, the Daaquam River, which also flows out of Canada. The Northwest Branch then runs generally eastward to its confluence with the Southwest Branch to form the Saint John River.
Has current flowing in:
On the Canadian side, the road 283 runs along the Canada-US border on and crosses the "Northwest Branch Saint John River" at the South East side of the Frontier Lake (Quebec-Maine).
On the US side, a road from Frontier Lake (Quebec-Maine) moves Eastward through the mountains. In addition, a road runs on the North bank on a river segment, downstream of the confluence of the Daaquam River and serves the township T11 R17 WELS in the North Maine Woods.
The river segment of between the bridge of the road 283 and the Canada-US border is considered an extension of Frontier Lake (Quebec-Maine). Consequently, the "Northwest Branch Saint John River" officially rises at the US border and not at the mouth of Frontière Lake in the municipality of Lac-Frontière, Quebec.
This source is located at Southeast of Lac Etchemin and Northeast of the Canada-US border.
From its source, the "Northwest Branch Saint John River" flows on of which in Quebec and in the Maine:
Higher courses of Northwest Branch Saint John River (segment of in Quebec)
Intermediate Course of the Northwest Branch Saint John River (segment of in Maine, up to the confluence of the Daaquam River)
Lower course of the Northwest Branch Saint John River (segment of downstream of the confluence of the Daaquam River)
"Northwest Branch Saint John River" flows on the Southwest bank of the Saint John River. This confluence is common with that of the Southwest Branch Saint John River (coming from South).
From the confluence of the Northwest Branch Saint-Jean River, the Saint John River flows Eastward and Northeast through Maine, then East and Southeast through New Brunswick. Finally, the current flows on the North bank of the Bay of Fundy which opens to the Southwest on the Atlantic Ocean.