Erosion is the displacement and deposition of soil particles. In short, it's the picking up and setting down of dirt. Erosion takes place when the soil is blown or washed off bare soil, such as a construction site. Erosion can also happen when there is more water in a creek than it was designed to hold. The rushing water can eat away at the sides of the stream. Dirt particles end up in the water and the stream banks can become unstable. More about stream bank erosion. Erosion is a concern for storm water professionals because it can harm water quality and our streams themselves.

When soil erodes the particles stay suspended in water for quite a while. This can clog fish gills, shade out aquatic life and make our streams appear "muddy".

When the particles finally fall to the bottom, the dirt often piles up on stream bottoms. The sediment can smother vegetation, cause the filling in of streams and ponds, and destroy aquatic habitat.

How can erosion be controlled? The best way to control erosion is to plant vegetation in bare soil. The roots of plants will bind the soil particles together and reduce the potential for erosion. Generally speaking, the larger the root system the more erosion control. So trees and shrubs are often used to stabilize stream banks while grasses are used to stabilize gentler slopes.