Streambank Revegetation and Protection: A Guide for Alaska
Revegetation Techniques: Live Siltation
Live siltation is a revegetation technique used to secure the toe of a slope, trap sediment and create fish rearing habitat. This technique may be installed behind other toe-of-slope protection. The practice can be constructed as a living brushy system at the water's edge. This technique is particularly valuable for providing immediate cover and fish habitat while other revegetation plantings become established.
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Collection, storage and planting information are described in Dormant Cuttings under the Plant Care and Preparation section. The dormant branches need to be a minimum of 3 feet long with side branches still attached. Feltleaf, Pacific or Sitka Willow is recommended for dormant cuttings (see Plant Species Selection List, Shrubs and Trees)
Construct a v-shaped trench above the ordinary high water (OHW) level, with hand tools or a backhoe. Excavate a trench so that it parallels the toe of the streambank and is approximately 2 feet deep. Lay a thick layer of willow branches (8"-10" before compaction) in the trench so that 1/3 of the length of the branches are above the trench and the branches angle out toward the stream. Place a minimum of 40 willow branches per yard in the trench. Of the 2/3 buried willow, not more than 1/2 should fall in permanently moist soil.
![caption follows](/static/lands/habitatrestoration/streambankprotection/images/livesilt1.jpg)
Backfill over the branches with a gravel/soil mix and secure the top surface with large washed gravel and/or bundles (see Bundles / Coir Logs sections). Both the upstream and downstream ends of the live siltation construction need to transition smoothly into a stable streambank to reduce the potential for the technique to wash out. More than one row of live siltation can be installed.
Advantages:
- Provides good fish habitat
- Provides bank stability in low velocity areas
- Provides good riparian vegetation
Disadvantages:
- Requires shallow water and slope
- Requires relatively low velocity
- Critical to know OHW (ordinary high water)
![caption follows](/static/lands/habitatrestoration/streambankprotection/images/livesilt2.jpg)
![caption follows](/static/lands/habitatrestoration/streambankprotection/images/livesilt3.jpg)