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Case Study: South Fork of the Salmon River, Idaho

Case Study Summary

Considerations for Using Ecological Restoration: Fine Sediment Loadings

Overall Project Goal: Restore populations of resident and anadromous salmonid species by reducing sediment loadings.

Restoration Techniques and Parameters of Concern: See table below.

                          ===========Parameter of Concern========

Restoration Technique/         Fish        Sediment     Cobble

Functional Attribute        Populations    Loadings  Embeddedness

============Reduction in Ground-Disturbing Activities============

Road closures and

     land reclamation            u             d          d   

Road reconstruction

     and relocation              u             d          d

BMPs for road building

     and forestry                u             d          d

=================Stream Stabilization Activities=================

Removal of sand from pools       u             d          d   

Instream gravel cleaning         u             o          d

Stream bank stabilization        u             d          d


Assessment of sediment

     reduction progress          u             d          d 

u means that the restoration technique increases water quality parameter;
d means that the restoration technique decreases water quality parameter;
ud means that site-specific conditions can dictate increase or decrease in parameter;
o means that the restoration technique has a negligible effect on water quality parameter.

Highlight on Techniques to Address Sediment Loadings with a Phased TMDL: Increased sediment loadings resulting from human activities had disrupted spawning sites for Chinook salmon and steelhead trout. Helping to restore those populations required reducing sediment loadings. The primary cause of sedimentation is road construction associated with forestry. An extensive data collection and modeling program was used to develop a numeric sediment criterion for the problem; then, a phased TMDL with an ongoing monitoring program was established. Initial projects are together expected to provide a 25-percent reduction in sediment yield, with goals for specific numeric sediment criteria specified. Additional sediment reduction projects have been identified for implementation if the first round of projects does not make sufficient progress toward restoration of spawning habitat.

For a more complete project description, including techniques to address additional parameters of concern, refer to Chapter 6.

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