The Weiser River is a 103-mile-long (166km)[3] tributary of the Snake River in western Idaho in the United States. It drains a mountainous area of 1,660 square miles (4,300km2) consisting primarily of low rolling foothills intersected by small streams south and east of Hells Canyon along the Idaho-Oregon border.
It receives the Little Weiser River from the east approximately 2 miles (3km) southwest of Cambridge. The river descends from approximately 8,000 feet (2,400m) above sea level at its source to 2,090 feet (640m) 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. 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.
