Arising in the Blue Mountains, it flows generally northwest to its confluence with the Columbia River upstream of Arlington.

[7] Willow Creek flows into the Columbia River approximately 253 miles (407 km) above its confluence with the Pacific Ocean.

Small and largemouth bass, black crappie, brown bullhead, bluegill, and pumpkinseed live in Willow Creek Lake.

The flash flood washed away one-third of the town's structures, killing 247 people in the "most deadly natural disaster in Oregon's recorded history."

One hundred and fifty homes were destroyed in the city of Ione, 20 miles (30 km) downstream; residents were able to evacuate because of advanced telephone warnings.