Soil Erosion

Lake Enemy #1 – Soil Erosion
Did you know that soil erosion from runoff accounts for approximately 67% of our unwanted phosphorus levels?

What is Soil Erosion and How Does it Affect Our Lakes?
Erosion is the loss of soil by the action of water, ice, gravity, or wind. Soil erosion is a natural process that can be greatly accelerated by human activities which remove protective vegetation and expose the soil. Soil erosion resulting from human activity can be as much as 100 times the natural erosion rate. When it rains the raindrops wash away the soil particles. These particles are then carried along by the runoff and combine with many other particles from the same area. The runoff flows to low points, usually a lake or river. This increases the sediment load or sedimentation of the waterbody. Too much sediment can be harmful to a waterbody.

Sediment can carry nutrients such as phosphorus, which act as natural fertilizers and promote the growth of algae. Too much algae reduces the water clarity and uses up the oxygen in the water that the fish and other organisms need to survive. Sediment deposits in shallow water areas can provide a good place where aquatic plants can proliferate. Soil erosion and sedimentation can also cloud the water and decrease the penetration of sunlight in deeper water. Over time this will decrease the depth of a lake and promote aquatic plant life. Sediment finally settles out and may smother important insects and plants that live on the lake bottom.

What Are the Conditions That Encourage Erosion?

  • The primary cause of soil erosion is the removal of protective grasses, shrubs and trees. This vegetative cover protects against erosion three primary ways: it shields the soil from the impact of raindrops; its “vegetative litter” made up of dead leaves, needles and twigs slow and filter the rainfall runoff, and its root system acts like a net and holds the soil together.
  • Soil containing large quantities of fine sand and silt are more erodible than other soils.
  • Exposed soils on long and/or steep slopes can promote soil erosion.
  • A large sloping area above and area of disturbed soil adds to the water flowing over the surface. More flowing water increases the erosion problem.
  • Poorly managed construction sites also encourage erosion.

How to Prevent Erosion

  • Preserve and promote growth of natural grasses, trees and shrubs to the greatest extent possible.
  • Minimize the area and the length of time soils are exposed.
  • Only disturb soil from May to mid-September when conditions favor proper erosion controls.
  • Use soil erosion control methods (such as mulch, matting, silt fences, or hay bales) during construction.
  • Divert runoff around areas or bare or disturbed soils.
  • NEVER have street runoff drain directly to the lake.

Landscaping Tips

  • Maintain the natural grass, trees and shrubs wherever possible.
  • Plant trees, shrubs, and ground covers, or use mulches to cover bare soil. Trees and plants and mulches trap and hold water.
  • Correct mowing height may be the single most important factor in the health of your lawn. Mowing height for most lawns should be about 2 to 3 inches. A healthy lawn holds rainwater, filters out dirt and pollutants, and requires less watering.
  • Leave grass clippings on the lawn. This reduces the need for fertilizers and water. (Lawn Fertilizers running into the lake promotes weed growth).

Sloping Property

  • Create terraces to slow runoff and prevent erosion on steep slopes.
  • Add a row of rocks or shrubs across a slop to interrupt water as it flows downhill.
  • Water with care. Do not soak lawn or garden areas on or near steep slopes.
  • When planting these areas select plants (especially native plants) that do not need intense or deep watering.
  • If you lay sod, place strips across, not down the slope.
  • Limit activity that disturbs the soil on unprotected steep slopes.

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