Natural erosion is generally considered to be due to the influence of climatic forces on the surface of the earth. While we can learn from the process of natural erosion, the practice of erosion control is usually limited to sites where human activities accelerate this natural process.
Erosion problems can be accelerated by a variety of human activities, including unrestricted development, overtaxed resources, removal of surface cover (such as vegetation), increased imperviousness (such as paving and rooftops) that increases runoff volume and velocity. These activities are evidence of poor stewardship of our soils and natural resources.
The goal of the EPA regulations on erosion is not to stop natural erosion. If we didn't have natural erosion, we would have no beaches. The goal of the regulations is to control accelerated erosion caused by human activities, so there is no net increase in sediment being discharged from a construction site over pre-construction conditions.
Construction-related erosion and sedimentation can cause problems for downslope property owners, create nuisance problems on adjacent streets, clog streams and storm drains, result in turbidity plumes in downstream water bodies, and can cover sensitive habitat areas (such as fish spawning beds) with sediment. The cumulative toll on the environment can be devastating. Uncontrolled erosion is costly; violates state and federal pollution laws; exposes developers, contractors, and landowners to legal liabilities; and provides ammunition to those who argue that the development process is out of control.
Water quality parameters that reflect the level of sediment yield are turbidity and suspended solids. As turbidity increases within a stream environment, photosynthetic activity may decrease with a subsequent potential decrease in available free oxygen necessary to support aquatic life. An increase in the concentration of suspended solids may destroy water supplies for human and wildlife consumption, as well as feeding and nesting habitats. Implementation of erosion control features consistent with sound construction operations can minimize the adverse impacts associated with increased sediment yield.