Boise River

The Boise River is a 102-mile-long tributary of the Snake River in the northwestern United States. It drains a rugged portion of the Sawtooth Range in southwestern Idaho northeast of Boise, as well as part of the western Snake River Plain. The watershed encompasses approximately 4,100 square miles of highly diverse habitats, including alpine canyons, forest, rangeland, agricultural lands, and urban areas.

The Boise River rises in three separate forks in the Sawtooth Range at elevations exceeding 10,000 feet , and is formed by the confluence of its North and Middle forks. The North Fork, 50 miles long, rises in the Sawtooth Wilderness Area, along the Boise–Elmore county line, 60 miles northeast of Boise. It flows generally southwest through the remote mountains in the Boise National Forest. The Middle Fork, approximately 52 miles in length, rises within 12 miles of the North Fork in the southern Sawtooth Wilderness Area in northeastern Elmore County. It flows west-southwest near the town of Atlanta, joining the North Fork to form the Boise River, approximately 15 miles southeast of Idaho City. The main stream flows southwest into Arrowrock Reservoir joining the South Fork from the Anderson Ranch Dam.

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