Tualatin River
| Tualatin River | |
 Mouth of the Tualatin River
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| Name origin: Probably an Indian word meaning "lazy" or "sluggish" but possibly meaning "treeless plain" for the plain near the river or "forked" for its many tributaries | |
| Country | United States |
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| State | Oregon |
| County | Washington, Clackamas |
| Source | Northern Oregon Coast Range |
| - location | near Windy Point, Tillamook State Forest, Washington County, Oregon |
| - elevation | 1,978 ft (603 m) |
| - coordinates | 45°28′55″N 123°24′21″W / 45.48194°N 123.40583°W |
| Mouth | Willamette River |
| - location | near West Linn, Clackamas County, Oregon |
| - elevation | 59 ft (18 m) |
| - coordinates | 45°20′17″N 122°39′05″W / 45.33806°N 122.65139°WCoordinates: 45°20′17″N 122°39′05″W / 45.33806°N 122.65139°W |
| Length | 83 mi (134 km) |
| Basin | 712 sq mi (1,844 km2) |
| Discharge | for near West Linn, 1.8 miles (2.9 km) from the mouth |
| - average | 1,465 cu ft/s (41 m3/s) |
| - max | 26,400 cu ft/s (748 m3/s) |
| - min | 0.20 cu ft/s (0 m3/s) |
  Location of the mouth of the Tualatin River in Oregon
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 Rivers in northwest Oregon
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The Tualatin River is a tributary of the Willamette River located in Oregon in the United States. The river is approximately 83 miles (134 km) long, and it drains a fertile farming region called the Tualatin Valley southwest and west of Portland at the northwest corner of the Willamette Valley. There are approximately 500,000 people residing on 15 percent of the land in the river's watershed.
The Tualatin River arises near Windy Point on the eastern side of the Northern Oregon Coast Range. It begins in the Tillamook State Forest in Washington County and flows about 83 miles (134 km) to the Willamette River near West Linn in Clackamas County. Along the way, it falls from about 2,000 feet (610 m) above sea level to about 60 feet (18 m), most of that occurring in its first 15 miles (24 km). From the unincorporated community of Cherry Grove, 68 miles (109 km) from the mouth, the river falls only about 220 feet (67 m) in meanders that trend generally east across the relatively flat Tualatin Valley.
From its source, the river flows south for about 1 mile (1.6 km) before turning east to parallel to Blind Cabin Ridge, which is to the river's . Shortly thereafter, the river plunges over the 40-foot (12 m) Ki-a-Kuts Falls, then receives Maple Creek from the and then Sunday Creek, also from the left, at river mile (RM) 76.7 (RK 123.4). Lee Creek enters from the left and Patten Creek from the right before the river reaches Hillsboro Reservoir and then Haines Falls at about RM 73 (RK 117). Hillsboro Reservoir Road and Southwest Lee Falls Road run roughly parallel to the river along its left back from the reservoir to the unincorporated community of Cherry Grove. Over the next stretch, the river runs roughly parallel to Hagerty Ridge, which is on the right. About 2 miles (3 km) further downstream, the river goes over Lee Falls and, shortly thereafter, Little Lee Falls before reaching Cherry Grove, which is on the river's left at the west end of Patton Valley. At Cherry Grove, the river passes under Roaring Creek Road, receives Roaring Creek from the right, passes under Bruce Road and Southwest S Road, and receives Hering Creek from the left. Thereafter, it flows under Northwest Mount Richmond Road and receives Mercer Creek from the left about 65 miles (105 km) from the river's mouth. Below this, Black Jack Creek enters from the left, and the river passes under Oregon Route 47 and flows by the city of Gaston, which is to the right.
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Wikipedia