Erosion Control

Soil erosion occurs naturally when rain falls. Runoff flows to the lowest point of the landscape. The velocity depends on the characteristics of the soils, the slope of the land and the vegetative cover.

Erosion can be a serious environmental problem when the land is disturbed by development, agriculture, or forestry. Surfaces like roads, roofs, driveways and hard-packed soils will not absorb water, and the runoff increases. Expanses of pavement like parking lots reduce the chances for ground water recharge. Exposed soils are lost and the land becomes less productive. Fertilizers and pesticides that may have been applied wash away, too, causing water quality problems for people living downstream.

Suspended silt keeps sunlight from penetrating waterbodies, robbing aquatic plants, animals, and fish of the light and oxygen they need to live. When silt eventually settles to the bottom, it can smother fish eggs and other aquatic life. Sediments can also reduce stream channel capacity, causing localized flooding.

Plants are a natural, inexpensive and highly effective means of controlling runoff. Runoff slows down and loses much of its erosional force when it reaches a strip of vegetation. Vegetation also works as a filter, straining out sediment, debris and other pollutants. You can do certain things to reduce erosion from your property.

Minimize hard surfaces and maximize the absorption capacity of your land.
Keep trees, shrubs, perennial grasses or legumes along steep slopes, drainage channels or ditches, and around bodies of water. Native plants generally survive best. The proper width of "buffer strips" of vegetation between land that is being used and water courses will depend on type of soil, degree of slope, and type of vegetative cover. Forested areas are more effective than grasslands for reducing erosion on steep slopes.
Use terraces or water bars to reduce runoff velocity on long or steep slopes.
Keep heavy equipment off exposed soil during the rainy season. Use gravel for parking areas.
Find out if there are erosion control regulations in your county's ordinances.

Take special precautions if you need to break ground.

Avoid disturbing soil in the autumn. Plan activities such as plowing, logging and construction for good weather, so vegetation covers the soil and protects it during rainy and freezing seasons.
When selecting a building site, avoid naturally wet areas or areas that may be unstable. Protect such areas before the rains start. Fabric fencing is a good erosion control method.
Think carefully how to divert runoff from erosion-prone areas. Keep sites small, disturbing only the amount of land absolutely necessary.
Save natural vegetation wherever possible, as a buffer zone and soil stabilizer.
Plant temporary vegetative cover (annual grasses or clovers) on sites that must remain exposed during the winter.
Use commercial hydromulch, straw or hay to help stabilize exposed or steep areas until vegetation is established.
If you have a wetland on your property, cherish and protect it. Order At Home with Wetlands: A Landowner's Guide. Call Ecology's publications office at (360) 407-7472 or e-mail and ask for publication #90-31.

For information and help: Contact your local conservation district, Soil Conservation Service agent, or your county cooperative extension office.

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