Salmon Falls Creek

Salmon Falls Creek
River
Looking upstream along Salmon Falls Creek Canyon
Country	United States
States	Nevada, Idaho
Tributaries
- left	North Fork Salmon Falls Creek, Cottonwood Creek, Cedar Creek, Big Creek
- right	South Fork Salmon Falls Creek, Jakes Creek, China Creek, Shoshone Creek
Cities	Jackpot, Nevada, Hollister, Idaho
Landmark	Salmon Falls Creek Reservoir
Source	Confluence of North and South Forks Salmon Creek
- elevation	5,643 ft (1,720 m)
- coordinates	41°47′22″N 114°57′43″W / 41.78944°N 114.96194°W / 41.78944; -114.96194
Mouth	Snake River
- location	Near Hagerman, Snake River Plain, Idaho
- elevation	3,431 ft (1,046 m)
- coordinates	42°42′55″N 114°51′12″W / 42.71528°N 114.85333°W / 42.71528; -114.85333Coordinates: 42°42′55″N 114°51′12″W / 42.71528°N 114.85333°W / 42.71528; -114.85333
Length	121 mi (195 km)
Basin	2,103 sq mi (5,447 km2)
Discharge	for Snake River
- average	345 cu ft/s (10 m3/s)
- max	7,500 cu ft/s (212 m3/s)
- min	0 cu ft/s (0 m3/s)
Map of Salmon Falls Creek

Salmon Falls Creek is a tributary of the Snake River, flowing from northern Nevada into Idaho in the United States. Formed in high mountains at the northern edge of the Great Basin, Salmon Falls Creek flows northwards 121 miles (195 km), draining an arid and mountainous basin of 2,103 square miles (5,450 km²). The Salmon Falls Creek valley served as a trade route between the Native American groups of the Snake River Plain and Great Basin. Today, most of its water is used for irrigation.

Salmon Falls Creek rises in the arid Jarbidge Mountains of northern Nevada at the confluence of its North and South Forks. The North Fork, sometimes considered the main stem of Salmon Falls Creek, is 24.3 miles (39.1 km) long, and the South Fork 12.1 miles (19.5 km) long. Many of the creek's headwater streams originate in the Humboldt National Forest and converge to form a short canyon. At the confluence with Jakes Creek the creek swings northeast into the O'Neil Basin, a valley along U.S. Highway 93, flowing north 40 miles (64 km), then passes the town of Jackpot and receives Shoshone Creek, its largest tributary, from the right.

From the Shoshone Creek confluence, Salmon Falls Creek enters another canyon that takes it 11 miles (18 km) across the Nevada-Idaho state border, merging with Cottonwood Creek, into Salmon Falls Creek Reservoir which is impounded by the arch concrete Salmon Falls Dam constructed across the creek between 1908–1910. After passing through the long and narrow lake, the creek cuts into a deep canyon as it enters the Snake River Plain, receiving Cedar Creek and Big Creek near Castleford. The creek empties into the Snake River 10 miles (16 km) south of Hagerman.

Before irrigation diversions began in the early 20th century, the average flow at the mouth was 345 cubic feet per second (9.8 m³/s). Following the construction of Salmon Falls Creek Reservoir and the diversion of many of its tributaries, the flow at its mouth from 2002 to 2005 averaged 116.5 cubic feet per second (3.30 m³/s). The average discharge upstream of the reservoir was 34.3 cubic feet per second (0.97 m³/s). Much of the flow in the last few miles is provided by four major irrigation drains that carry runoff from the extensive agricultural areas surrounding lower Salmon Falls Creek, because all the water released from Salmon Falls Creek Reservoir is diverted shortly below the dam. Work has been done to reduce pollutants flowing into the lower creek from these drains, including excess nitrogen, phosphorus and fecal coliforms.