Washington State Department of Ecology

Contour Wattling

Wattling system can be used as slope drains when angled slightly across a contour. Contour wattling is an erosion control planting method which can also be used to stabilized very shallow soil structure against landsliding.

The method involves packing lengths of woody plant material into cables or bundles (sometimes called live fascines) about 8 to 10 inches in diameter as shown in Figure 16. The bundles are laid continuously along slope contours as shown in Figure 17. The cabling effect along the slope helps to intercept surface water runoff and route it laterally before it creates erosion problems. The wattles help trap sediment by creating barriers (living fences) to protect down slope areas against material falls or erosion.

Figure 16. Wattle detail

Woody plants which are particularly suitable to contour wattling are willow, red-osier dogwood, and snowberry. Wattling is generally considered good for slopes of 1.5H:1V or less. The installation of wattles along slopes requires a greater degree of planning prior to installation. Generally, wattles are placed horizontally in shallow trenches along preselected alignments on the slope at a single contour elevation. The wattles are placed into the trenches and partially covered creating what appear like slope terraces. Wattling installation along a slope face should progress from the slope toe upslope to the crest until planting is complete. The Ecology booklet Slope Stabilization and Erosion Control Using Vegetation describes wattling techniques in detail.

Figure 17. Contour wattling.

Limitations: There is a significant quantity of plant material required for this technique. Installation is best performed with a labor crew of 3 to 4 people. The technique is time consuming if quality work is performed. For dry sites, summer watering may be initially necessary.
Advantages: Good erosion control technique, can be used to manage mild gully erosion, can serve as slope drains when wattle cables are angled slightly.
Disadvantages: On steep or long slope lengths, high runoff velocities can undermine wattling near drainage channels, can dry out if not properly installed, covered, or maintained. Routed drainage must be collected into stable swales at slope toe.

	Applicability	Compatibility

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