Clackamas River

Clackamas River
Clackamas River Bridge at Oregon City
Map showing the Clackamas River highlighted within the Willamette River watershed
Location of the mouth of the Clackamas River in Oregon
Etymology	Clackamas tribe
Location
Country	United States
State	Oregon
Counties	Marion and Clackamas
Physical characteristics
Source	near Olallie Butte
• location	Cascade Range, Marion County, Oregon
• coordinates	44°49′17″N 121°47′47″W / 44.82139°N 121.79639°W / 44.82139; -121.79639[1]
• elevation	4,909 ft (1,496 m)[2]
Mouth	Willamette River
• location	Oregon City and Gladstone, Clackamas County, Oregon
• coordinates	45°22′21″N 122°36′31″W / 45.37250°N 122.60861°W / 45.37250; -122.60861[1]
• elevation	10 ft (3.0 m)[1]
Length	83 mi (134 km)[3]
Basin size	940 sq mi (2,400 km2)[4]
Discharge
• location	1.5 miles (2.4 km) northwest of Estacada, 23.1 miles (37.2 km) from mouth[5]
• average	2,750 cu ft/s (78 m3/s)[5]
• minimum	285 cu ft/s (8.1 m3/s)
• maximum	86,900 cu ft/s (2,460 m3/s)
National Wild and Scenic River
Type	Scenic, Recreational
Designated	October 28, 1988

The Clackamas River is an approximately 83-mile (134 km) tributary of the Willamette River in northwestern Oregon, in the United States. Draining an area of about 940 square miles (2,435 km²), the Clackamas flows through mostly forested and rugged mountainous terrain in its upper reaches, and passes agricultural and urban areas in its lower third. The river rises in eastern Marion County, about 55 miles (89 km) east-southeast of Salem. The headwaters are on the slopes of Olallie Butte in the Mount Hood National Forest, about 10 miles (16 km) north of Mount Jefferson, at an elevation of 4,909 feet (1,496 m) in the Cascade Range. The Clackamas flows briefly north and then flows northwest through the mountains, passing through North Fork Reservoir and Estacada. It then emerges from the mountains southeast of Portland. It joins the Willamette near Oregon City and forms the boundary between Oregon City and Gladstone.

The Clackamas provides hydroelectric power and drinking water for some of the Portland metropolitan area, and it supports runs of Coho salmon, spring and fall Chinook salmon, and summer and winter steelhead. The river's old-growth forests, its habitat for several species of birds, its healthy fish runs, and the recreational opportunities that it provides—such as fishing and whitewater rafting—led to the designation of more than half of the length of the river into the National Wild and Scenic Rivers System (NWSRS). This environment also allowed Native Americans to settle in the river's basin as early as 10,000 years ago.

Regulation of the river began in 1905 with the Cazadero Dam. In 1912, the River Mill Dam intercepted wood and coarse sediment. Later dams at North Fork, Oak Grove, Stone Creek, and Timothy Lake also intercepted wood sediment on the lower river.