The Aroostook River
is a tributary of the Saint John River
, approximately 140 mi (225 km) long, in the U.S. state
and the Canadian province
of New Brunswick
. Its basin is the largest sub-drainage of the St.John River. The river rises in northeastern Maine and winds E and NE through Aroostook County
. It runs through Ashland
, and passes north of Presque Isle
and east of Caribou
. It joins the St. John in western New Brunswick two miles (3 km) after crossing the International Boundary
The United States government maintains two river flow gages on the Aroostook. The first is located near Masardis, Maine where the rivershed is , the second at Washburn, Maine where the rivershed is . By Fort Fairfield, Maine the rivershed is . At Masardis, the maximum recorded flow is 21,100 cubic feet per second and the minimum per second. At Washburn, the maximum recorded flow is per second and the minimum per second. Annual maximum flows occur during the spring snow melt and minimums in the fall. The highest flood levels at both gages occurred during ice-dam induced floods, which occur relatively often on this river. Such flooding occurred in March and April 1999, April and May 2003, and April 2004.
The river has a small run of Atlantic Salmon. From 1998 to 2001 the number of adults returning to the river ranged from seventeen to thirty.
The International Appalachian Trail runs along the river for several miles. Hikers cross the river, pass through customs, and cross the international boundary at Fort Fairfield, Maine.
In the late 1830s, the territory comprising the river's drainage area was scene of the Aroostook War, a boundary dispute between the United States and the United Kingdom.