Lostine River

The Lostine River is a 31.4 mi tributary of the Wallowa River in northeastern Oregon in the United States. It drains a portion of the Eagle Cap Wilderness of the Wallowa Mountains in the Wallowa–Whitman National Forest and joins the Wallowa River at Wallowa.

In 1988, the upper 16 mi of the Lostine River were listed as Wild and Scenic. A 5 mi segment in the wilderness below the river's source at Minam Lake were classified "wild". The next 11 mi were designated "recreational".

The main stem rises at Minam Lake at an elevation of nearly 7400 ft above sea level, about 15 mi south of the city of Lostine and 10 mi west-southwest of Joseph. The river flows generally north following a glaciated U-shaped canyon. It exits the national forest at an elevation of 3930 ft and gradually changes character as it reaches more level terrain which slopes gradually down to 3000 ft, where it meets the Wallowa River. The river's flow varies seasonally from about 50 to 1000 cuft/s.

Irrigation diversions, which play a significant role in the river, contributed to the extinction of the local run of Coho salmon in the 1960s and reduced the population of the run of spring Chinook salmon to a low of 13 fish in 1999. Both runs had been an historic source of food for the Nez Perce people. The Nez Perce began restoration efforts in the 1990s, and by 2005, the Chinook salmon run had risen to 800 fish. An agreement that year among farmers, the Nez Perce, and the Oregon Water Trust led to efforts to preserve the stream flow during summer, helping the salmon to survive. By 2009, the run had increased to more than 2,000 Chinook salmon.