| South Fork Salmon River | |
| Map: | Salmon river basin map.png |
| Map Size: | 300 |
| Subdivision Type1: | Country |
| Subdivision Name1: | United States |
| Subdivision Type2: | State |
| Subdivision Name2: | Idaho |
| Length: | 86miles |
| Discharge1 Location: | Mackay Bar |
| Discharge1 Min: | 318cuft/s |
| Discharge1 Avg: | 1983cuft/s |
| Discharge1 Max: | 21600cuft/s |
| Source1: | near Monumental Peak |
| Source1 Location: | Salmon River Mountains, Valley County |
| Source1 Coordinates: | 44.4797°N -115.685°W |
| Source1 Elevation: | 7600feet |
| Mouth: | Salmon River |
| Mouth Location: | near Mackay Bar, Idaho County |
| Mouth Coordinates: | 45.3778°N -115.5131°W |
| Mouth Elevation: | 2146feet |
| Basin Size: | 1309sqmi[1] |
| Tributaries Left: | Secesh River |
| Tributaries Right: | East Fork, Elk Creek |
The South Fork Salmon River is an 86miles[2] tributary of the Salmon River in Idaho and Valley Counties in central Idaho.[3] The river drains a rugged, lightly populated wilderness watershed in the Salmon River Mountains. It is the second-largest tributary of the Salmon River, after the Middle Fork.
Beginning near 7902feet Monumental Peak in the Boise National Forest, the river flows generally north to its confluence with the Salmon near Mackay Bar, about 135miles above the larger river's mouth on the Snake River. About midway along its course, it is joined by its two main tributaries – the East Fork South Fork Salmon River from the east and the Secesh River from the west.[4] The river receives runoff from a total of 1309mi2 of land, ranging in elevation from 9322feet at North Loon Mountain to 2146feet at the mouth of the river.[1]
The Native Americans living along the river were the Nez Perce, Shoshone, Bannock and Paiute. The river and its valley were used largely for fishing, hunting, and gathering, while local hot springs provided camping sites during the winter.
The first recorded Europeans to see the South Fork may have been a group of mountain men working under the American Fur Company in 1831. They crossed the upper part of the river while reconnoitering the western part of the Salmon River system for good beaver streams.[5] In the 1860s, prospectors discovered gold on the South Fork, leading to the initial settlement of the drainage by Westerners. After the gold rush faded, some miners stayed on as homesteaders and ranchers.
The drainage was heavily logged from the 1940s to the mid-1960s, when an estimated 320 million board feet of timber was taken from the basin. More than 800miles of logging roads were constructed across the drainage.
The South Fork is an important habitat for Chinook salmon, Westslope cutthroat trout, bull trout and steelhead trout and has been designated critical habitat for salmon. Although the aquatic habitat in the South Fork drainage is considered good, some tributaries have been damaged by logging, mining, and road-building activities, which has increased the sediment load in the river. About 340miles of backcountry roads in the drainage have been decommissioned and are undergoing restoration by the U.S. Forest Service.[6] [7]
Plant communities in the South Fork drainage range from grassland and shrubland, Ponderosa pine, Douglas fir and Grand fir forests at lower elevations, to subalpine fir, lodgepole pine, whitebark pine and aspen at mid to high elevations.[7] Among large mammals, the watershed is home to Rocky Mountain elk, white-tailed deer, mule deer, black bear, cougar, mountain goat, bighorn sheep and gray wolf. The area has over 200 confirmed species of resident and migratory birds.[6]
The United States Geological Survey (USGS) operated a stream gage at the mouth of the South Fork between 1993 and 2003, recording an annual mean of 1983cuft/s. The highest annual mean was 3125cuft/s in 1997, and the lowest was 869.9cuft/s in 2001. Mean monthly discharge rates for the South Fork are displayed in the below graph.
Monthly discharges at Mackay Bar (cfs)[1]
ImageSize = width:800 height:280PlotArea = left:60 bottom:30 top:30 right:60DateFormat = x.yPeriod = from:0 till:10000TimeAxis = orientation:verticalAlignBars = justifyScaleMinor = gridcolor:lightgrey increment:1000 start:0BackgroundColors = canvas:sfondo
BarData= bar:Jan text:Jan. bar:Fév text:Feb. bar:Mar text:Mar. bar:Avr text:Apr. bar:Mai text:May bar:Jun text:Jun. bar:Jul text:Jul. bar:Aoû text:Aug. bar:Sep text:Sep. bar:Oct text:Oct. bar:Nov text:Nov. bar:Déc text:Dec.
PlotData= color:barra width:30 align:left
bar:Jan from:0 till: 774 bar:Fév from:0 till: 755 bar:Mar from:0 till: 1020 bar:Avr from:0 till: 2280 bar:Mai from:0 till: 6600 bar:Jun from:0 till: 7060 bar:Jul from:0 till: 2040 bar:Aoû from:0 till: 759 bar:Sep from:0 till: 544 bar:Oct from:0 till: 547 bar:Nov from:0 till: 674 bar:Déc from:0 till: 747
PlotData= bar:Jan at: 774 fontsize:S text: 774 shift:(-8,5) bar:Fév at: 755 fontsize:S text: 755 shift:(-8,5) bar:Mar at: 1020 fontsize:S text: 1,020 shift:(-13,5) bar:Avr at: 2280 fontsize:S text: 2,280 shift:(-13,5) bar:Mai at: 6600 fontsize:S text: 6,600 shift:(-13,5) bar:Jun at: 7060 fontsize:S text: 7,060 shift:(-13,5) bar:Jul at: 2040 fontsize:S text: 2,040 shift:(-13,5) bar:Aoû at: 759 fontsize:S text: 759 shift:(-8,5) bar:Sep at: 544 fontsize:S text: 544 shift:(-8,5) bar:Oct at: 547 fontsize:S text: 547 shift:(-8,5) bar:Nov at: 674 fontsize:S text: 674 shift:(-8,5) bar:Déc at: 747 fontsize:S text: 747 shift:(-8,5)
Although not as frequently run as the Middle Fork, the South Fork is also well known for challenging whitewater. Boaters frequently put in at the Secesh River, about 37miles above the mouth of the South Fork on the main stem Salmon. Because of their relatively pristine condition, the South Fork and its tributary, the Secesh are being considered for inclusion in the National Wild and Scenic Rivers system.[7]