The Tualatin River is a tributary of the Willamette River, approximately 83 mi (125 km), in Oregon in the United States. It drains a fertile farming region called the Tualatin Valley southwest and west of Portland at the northwest corner of the larger Willamette Valley.
It rises in the Coastal Range in southwestern Washington County, near the town of Cherry Grove and flows northward, passing south of Forest Grove, then generally eastward, passing south of Hillsboro, then southeastward through the town of Tualatin. It empties into the Willamette south of West Linn. The drainage area of the Tualatin is approximately 712 square miles.
The valley of the Tualatin was an important farming region early in the early white settlement of Oregon. The building of a plank road to the Tualatin Valley from Portland in 1860 is considered by historians to be one of the principal reasons for the rise of Portland as the dominant city in the region. The valley contains numerous natural wetlands, part of which have been designated as the Tualatin River National Wildlife Refuge.
It receives Dairy Creek from the north near Hillsboro. It receives Chicken Creek from the south near Sherwood.
Located on the outskirts of Portland, TualatinRiver National Wildlife Refuge is one of only a handful of urban national wildlife refuges in the country.
Situated within the floodplain of the TualatinRiver, the Refuge comprises less than 1% of the 712 square mile watershed.
TualatinRiver National Wildlife Refuge is one of over 540 refuges in the National Wildlife Refuge System--a network of lands and waters set aside specifically for wildlife.