Grande Ronde River

The Grande Ronde River rises in the Blue Mountains near the Anthony Lakes recreation area in the Wallowa–Whitman National Forest in southwestern Union County approximately 20 miles (32 km) south of La Grande. It flows generally north along the east side of the Blue Mountains, then east, past La Grande, then generally northeast through the Grande Ronde Valley in a meandering course between the Blue Mountains and the Wallowa Mountains, receiving Catherine Creek east of La Grande.

Approximately 10 miles (16 km) northwest of Minam it receives the Wallowa River from the southeast, then receives the Wenaha River at Troy just south of the Washington border. It crosses into southeastern Washington, traversing the extreme southeast corner of the state and entering the Snake from the east, approximately 5 miles (8 km) north of the Oregon border and 15 miles (24 km) downstream from the mouth of the Salmon River. It receives Joseph Creek from the south 2 miles (3.2 km) upstream from its mouth on the Snake.

The mouth of the Grande Ronde River is at the Snake's river mile 169, which is 493 miles (793 km) from the mouth of the Columbia River.

https://en.wikipedia.org/wiki/Grande_Ronde_River