South Fork Salmon River

Idaho Department of Fish & Game

A Diverse Watershed

The South Fork of the Salmon River drains about 827,000 acres of central Idaho, an area slightly larger than the State of Rhode Island.

The rugged watershed ranges in elevation from 2,170 to 9,280 feet. It originates in high mountain meadows east of Cascade and joins the Salmon River at Mackay Bar 82 miles later.

It contains a great diversity of natural resources, including valuable timber and minerals, wilderness and roadless areas, and abundant fish and wildlife.

More than 200 species of birds inhabit the drainage. Large mammals include Rocky Mountain elk, mule and white-tailed deer, black bear, cougar, mountain goat, bighorn sheep, and the gray wolf.

The cool, clear waters of the South Fork and its tributaries support resident trout and nationally significant populations of anadromous (ocean-migrating) salmon and steelhead.

Chinook Salmon History

Photo of a sign on the forest - Salmon Country! Healthy Rivers KeepThe South Fork Salmon River contains the most important remaining habitat for summer chinook salmon in the Columbia River basin. The fish were once the largest, most valuable segment of the world’s largest runs of chinook salmon.

Their numbers have drastically declined in the wake of several factors: habitat blocked by dams, overfishing in marine and freshwater fisheries, habitat degradation, hatchery competition, and mortality of juveniles and adults at the Snake and Columbia River hydroelectric projects.

A main factor in the South Fork has been habitat degradation from sedimentation-both natural and human caused. The sediment significantly reduces chinook egg and juvenile survival.

Adult salmon returning to this river reached an estimated 10,000 fish in the mid-1950’s. The count declined to only 250 by 1979.

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Therefore, the National Marine Fisheries Service listed the chinook salmon as a threatened species in 1992.

South Fork Fisheries

The South Fork Salmon River is one the few areas in the entire Columbia River basin that has reasonably intact assemblages of native fishes, including bull trout, westslope cutthroat, chinook salmon, and proposed-threatened steelhead trout. There have even been historical sightings of endangered sockeye salmon.

The Boise and Payette National Forest Plans have as a primary objective restoring and protecting summer chinook salmon habitat in the South Fork drainage. The Plans call for a large number and variety of habitat improvement projects to that end. Many have been completed, many have yet to be done.

The State of Idaho has listed much of the South Fork Salmon River as a “Water Quality Limited Segment” under provisions of the Clean Water Act. This requires the stream to be protected from further degradation by sediment. It has also designated the river a “Stream Segment of Concern” which provides for special protection of beneficial uses.

Despite some areas in poor condition, overall condition of fish habitat in the watershed remains good because most of its acreage has not been roaded or developed and is nearly intact.

Critical Habitat

The National Marine Fisheries Service has designated critical habitat for chinook salmon. It includes all tributaries of the Salmon River presently or historically accessible to chinook salmon. This includes essentially the entire South Fork system. Within critical habitat, an agency must avoid actions that destroy or adversely modify that critical habitat.

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The Fisheries Service has recently proposed that steelhead trout be added to the threatened and endangered species list.

Land Use Impacts

Nearly the entire South Fork Salmon watershed lies within a geological formation called the Idaho Batholith. Covering much of central Idaho and western Montana, the batholith rock weathers to shallow, coarse-textured soils that are highly susceptible to erosion. Sandy, white, loose soil on very steep slopes is typical of the entire watershed.

Before the mid 1940’s, extensive grazing, mining, and roadbuilding took place in the watershed. The activities generated large amounts of sediment into the river and its tributaries.

From the 1940’s to mid 1960’s, more than 800 miles of road were constructed and 320 million board feet of timber harvested from the South Fork Salmon River watershed. Many roads cut across steep, fragile terrain.

  • Winter 1964-5

Rain-on-snow storms in 1964-1965 caused massive erosion of logged areas and roads. Tremendous amounts of sediment-estimated up to 1.5 million cubic yards-washed into the South Fork and tributaries. This had a devastating impact on aquatic life including chinook salmon and steelhead. These fish require relatively sediment-free gravels in which to lay their eggs.

In 1965, the Forest Service declared a moratorium on logging and road construction in the drainage. It began watershed rehabilitation. By the mid-1970’s, over 340 miles of logging roads had been closed and revegetated, and other erosion controls installed. These activities and natural stream flushing action significantly reduced the amount of sediment entering the South Fork system.

  • Monitoring

The Forest Service has invested several million dollars in erosion control and monitoring over the last three decades. It has also severely restricted land-disturbing activities. Monitoring results from the 1980’s show no conclusive evidence of improvement in sediment levels or chinook habitat. Apparently, the amount of sediment then in the system, plus the new sediment being delivered, exceeded the drainage’s ability to transport sediment out of the system.

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Latest monitoring results from the mid-1990’s may indicate recent gradual improvement in parts of the South Fork.

  • Wildfires

In the summer of 1994, lightning sparked two major wildfires that burned in the watershed: the Thunderbolt Fire in the middle drainage, and the Chicken Fire in the lower drainage. The fires were generally within the range of historic variation, within Forest Plan projections, and caused few negative impacts on anadromous fish habitat.

In 1995 the Forest Service analyzed the landscape conditions, and proposed several timber salvage projects in the two fire areas. They were harvested during the summer of 1996. The salvage projects were designed to achieve improvement in chinook salmon habitat in the long term, while obtaining economic value from the burned timber.

If You Visit

Caution! Be extremely careful not to damage chinook salmon habitat.

You can:

  • Keep streams free of grease, oil, soap, litter.
  • Keep vehicles and campsites away from lakes and streams.
  • Use bridge crossings.
  • Be careful where you wade or swim.
  • Do not cut or harm vegetation along streams.
  • Keep your distance from salmon.

Speak up for the salmon. Report violations!

Healthy rivers keep them coming back. Please help them make it! For More Information Contact the New Meadows, McCall, or Krassel Ranger District: New Meadows (208) 347-0300 McCall (208) 634-0400 Krassel (208) 634-0600