South Fork Coquille River

South Fork Coquille River
The lower tier of Coquille River Falls at low water
Country	United States
State	Oregon
Region	Coos County
Tributaries
- left	Johnson Creek, Salmon Creek, Dement Creek, Catching Creek
- right	Wooden Rock Creek, Coal Creek, Woodward Creek, Middle Fork Coquille River
Cities	Powers, Broadbent, Myrtle Point
Source	Southern Oregon Coast Range
- location	Unnamed ridge, north of Mount Bolivar
- elevation	3,501 ft (1,067 m)
- coordinates	42°50′24″N 123°52′30″W / 42.84000°N 123.87500°W / 42.84000; -123.87500
Mouth	Coquille River
- location	Myrtle Point
- elevation	13 ft (4 m)
- coordinates	43°04′49″N 124°08′29″W / 43.08028°N 124.14139°W / 43.08028; -124.14139Coordinates: 43°04′49″N 124°08′29″W / 43.08028°N 124.14139°W / 43.08028; -124.14139
Length	62.8 mi (101 km)
Basin	288 sq mi (746 km2)
Discharge	for Powers
- average	778 cu ft/s (22 m3/s)
- max	48,900 cu ft/s (1,385 m3/s)
- min	7.2 cu ft/s (0 m3/s)
Location of the mouth of the South Fork Coquille River in Oregon

The South Fork Coquille River is the longest tributary of the Coquille River in coastal Oregon in the United States. From its headwaters in the Southern Oregon Coast Range, the river flows northwest to join the North Fork Coquille River at Myrtle Point, forming the main stem Coquille. The South Fork is about 63 miles (101 km) long, and its watershed drains roughly 288 square miles (750 km²) of rural Coos County.

The South Fork rises as a small stream draining out of Eden Valley, 2.5 miles (4.0 km) northwest of Mount Bolivar in the Siskiyou National Forest. Picking up scores of tributaries, such as Wooden Rock, Clear and Panther Creeks, the river gains volume as it flows southwest into a deep gorge. At the confluence with Rock Creek, the river abruptly swings north, receiving Johnson Creek from the left a few miles further downstream. Now a fairly large stream, the South Fork winds through canyons to the confluence with Coal Creek before entering an alluvial valley near the small community of Powers.

Below the city, the South Fork flows north through a canyon into another broad valley, now followed by Oregon Route 542, and passing Coquille Myrtle Grove State Natural Site and Albert H. Powers Memorial State Park. About a mile downstream, Dement Creek enters from the left and the terrain around the river transforms from hills to farmland. As it assumes a meandering course, the river passes Broadbent, then the Middle Fork Coquille River, by far the largest tributary, enters from the right, marking the head of tide. A few miles onward, the river passes Myrtle Point and meets the North Fork to form the Coquille River about 36 miles (58 km) upstream of the Pacific Ocean.