Saint John River - Upper, NB

The Saint John River (French: Fleuve Saint-Jean) is a river, approximately 418 miles (673 km) long, located principally in the Canadian province of New Brunswick but also in, and arising from the province of Quebec and the U.S. state of Maine. It forms part of the Canada – United States border in two different places along its length. The river drains an area of approximately 55,000 square kilometres (21,000 sq mi), of which slightly more than half is located in New Brunswick. Along that portion of the Atlantic shoreline of North America that lies between the St. Lawrence River and the Mississippi River, the Saint John River is the second longest waterway; only the Susquehanna is longer. The lower section of the Saint John River (extending from Fredericton to the City of Saint John) is nicknamed the "Rhine of North America" in reference to its popularity for recreational boating. The head pond of the river is located in Mactaquac, New Brunswick and is very popular for boating, water skiing and swimming.

The Baker Branch of the Saint John River rises in the Saint John Ponds of Somerset County in northwestern Maine. The Southwest Branch of the Saint John River originates in Little Saint John Lake on the Maine–Quebec border near Saint-Zacharie, Quebec and forms the international boundary between Maine and Quebec as it flows northeasterly to join the Baker Branch in northern Somerset County. The Northwest Branch of the Saint John River rises from Lac Frontière, in Montmagny Regional County Municipality near the southeastern Quebec border and flows southerly through Maine to a confluence with the Daaquam River and then easterly to a confluence with the Southwest Branch.

The branches combine to form the main river flowing northeastward through western Aroostook County (46°33′47″N 69°53′06″W). The Lacroix road built in 1923 from Lac-Frontière crosses the river at Ninemile Bridge. Near Seven Islands the river was crossed by an 18th century trail from the St. Lawrence River. There is an Abenaki burial site containing a large number of graves where the Big Black River joins the Saint John in township 18, range 13, WELS. Local legend maintains the confluence is haunted by the spirits of Abenaki killed by an epidemic of European disease.[4] Near Allagash, the Saint John is joined by the Allagash River. The whole portion of the Saint John River that lies entirely in Maine is essentially a wilderness waterway, although many smoothly weathered granite boulders within the channel were broken by blasting during early 20th century log driving. Below St. Francis, the Saint John begins to form part of the International Boundary between Maine and New Brunswick.

Continuing its northeasterly course, the river passes Fort Kent, Maine, and then flows between Edmundston, New Brunswick, and Madawaska, Maine, where it turns southeast, passing between Van Buren, Maine, and St. Leonard, New Brunswick. Near Grand Falls, New Brunswick, the river enters entirely into New Brunswick, and changes direction to flow due south through the fertile Upper Saint John River Valley, framed by the rising hills of the Appalachian range in Victoria and Carleton counties. At Perth-Andover, the river is joined by the Aroostook and the Tobique rivers. At Hartland, it is crossed by the longest covered bridge in the world.
Mactaquac Dam

Further south at Woodstock, the river leaves the Upper Valley and turns east, heading away from the border region. It is joined by the Nackawic stream at Nackawic and passes small communities such as Bear Island. After passing the Mactaquac Dam it continues eastward until it eventually reaches New Brunswick's capital city Fredericton (where it becomes navigable), and then the military town of Oromocto. Turning south from Oromocto, the river is joined by the short Jemseg River which empties New Brunswick's largest lake, Grand Lake. This part of the river valley becomes broad and shallow and the river meanders through many low islands used for pastureland during dry periods in the summer and fall.

South of the Jemseg, the Saint John River is surrounded by the low hills of the St. Croix Highlands. It is joined by several lateral bays; including Belleisle Bay, the Nerepis River and the Kennebecasis River. The Saint John River finally discharges into the Bay of Fundy. The industrial city of Saint John is located at the mouth of the river. Near the river's mouth, there is a unique phenomenon (the Reversing Falls), caused by the high tides of the Bay of Fundy. These tides are the highest in the world and cause the river to reverse its flow twice a day in a narrow gorge in the city's centre.

The Saint John River has a maximum depth of 50 metres