DescriptionIt rises in northern Adams County, Idaho, Adams County in the Seven Devils Mountains, approximately west of New Meadows, Idaho, New Meadows in the Payette National Forest. It flows generally southwest, between the Cuddy Mountains to the west and the West Mountains to the east, past Council, Idaho, Council and Cambridge, Idaho, Cambridge. In southern Washington County, Idaho, Washington County it turns west for its lower and enters a broadening valley called the Weiser Cove along the northwestern extreme of the Snake River Plain before entering the Snake from the east at Weiser, Idaho, Weiser. It receives the Little Weiser River from the east approximately southwest of Cambridge. The river descends from approximately above sea level at its source to at its mouth on the Snake. For much of its upper reaches, the river follows a narrow course through the mountains, emerging at times into several broad ranching valleys, including one around Midvale, Idaho, Midvale. Although it flows unimpeded, it is used for irrigation in the vicinity of its mouth upstream from Weiser, as well along tributaries in its upper reaches. The Pacific and Idaho Northern Railroad formerly followed its course from Weiser to New Meadows. The river, as well as the town of Weiser, Idaho, Weiser, are named for Private Peter M. Weiser of the Lewis and Clark Expedition of 1804-1806.
See also* List of Idaho rivers * List of longest streams of Idaho