The Big River is a tributary of the Coast Fork Willamette River

Coast Fork Willamette River

The Coast Fork Willamette River is one of several forks that unite to form the Willamette River in western Oregon in the United States. It is about long, draining an area of the mountains at the south end of the Willamette Valley south of Eugene.-Course:...

, approximately 12 mi (19 km) long, in western Oregon

Oregon

Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...

 in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. It drains an area of the Calapooya Mountains

Calapooya Mountains

The Calapooya Mountains are a mountain range in Lane and Douglas counties of southwestern Oregon in the United States. The range runs for approximately west from the Cascade Range between Eugene on the north and Roseburg on the south.- Geology :...

 south of Eugene

Eugene, Oregon

Eugene is the second largest city in the U.S. state of Oregon and the seat of Lane County. It is located at the south end of the Willamette Valley, at the confluence of the McKenzie and Willamette rivers, about east of the Oregon Coast.As of the 2010 U.S...

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It rises in northern Douglas County

Douglas County, Oregon

-National protected areas:* Crater Lake National Park * Rogue River-Siskiyou National Forest * Siuslaw National Forest * Umpqua National Forest * Willamette National Forest -Adjacent counties:* Lane County, Oregon -...

, northwest of Huckleberry Mountain, approximately 20 mi (32 km) south-southeast of Cottage Grove

Cottage Grove, Oregon

Cottage Grove is a city in Lane County, Oregon, United States. It received its name from its first postmaster, G. C. Pierce, in September 1861. Pierce's home at the time was in an oak grove. The population was 9,686 at the 2010 census.-History:...

 at 43.5403984°N 122.8978409°W. It flows northwest through Lane County

Lane County, Oregon

-National protected areas:*Oregon Islands National Wildlife Refuge *Siuslaw National Forest *Umpqua National Forest *Willamette National Forest -Government:...

 to form the Coast Fork of the Willamette at its confluence with Garoutte Creek, approximately 15 mi (24 km) south of Cottage Grove at 43.5953987°N 123.0675727°W

Course

Flowing northwest from the northern flanks of the Calapooya Mountains in Douglas County, Big River enters Lane County about 1 miles (1.6 km) downstream from the source. Box Canyon enters from the right at about river mile

River mile

In the United States, a River mile is a measure of distance in miles along a river from its mouth. River mile numbers begin at zero and increase further upstream. The corresponding metric unit using kilometers is the River kilometer...

 (RM) 9 or river kilometer (RK) 14. Big River receives Boulder Creek from the left, then Edwards Creek enters from the right at about RM 6 (RK 10). After receiving Bar Creek from the left and Martin Creek from the right, Big River meets Garoutte Creek to form the Coast Fork Willamette River about 40 miles (64.4 km) from where the larger stream meets the Middle Fork Willamette River

Middle Fork Willamette River

The Middle Fork Willamette River is one of several forks that unite to form the Willamette River in the western part of the U.S. state of Oregon...

 to form the Willamette River

Willamette River

The Willamette River is a major tributary of the Columbia River, accounting for 12 to 15 percent of the Columbia's flow. The Willamette's main stem is long, lying entirely in northwestern Oregon in the United States...

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