The Sandy River is a 56-mile (90 km) tributary of the Columbia River in northwestern Oregon in the United States. Measured by a United States Geological Survey (USGS) gauge downstream of the Sandy's confluence with the Bull Run River, 18.4 miles (29.6 km) from the mouth, the river's average discharge is 2,300 cubic feet per second (65 m3/s). The maximum daily recorded flow is 84,400 cubic feet per second (2,390 m3/s), and the minimum is 45 cubic feet per second (1.3 m3/s).[6] The Sandy joins the Columbia about 14 miles (23 km) upstream of Portland.