This fact sheet explains how soils influence water quality and why efficient soil management helps protect water quality. When a soil is well managed, it can be an efficient receiver of rainwater. If the soil is improperly managed, however, the water may run off the surface, carrying soil particles with it. Damage to water quality occurs when this eroded soil enters surface waters. Figure 1 .
Runoff water can transport chemicals and remove uniform amounts of soil from a wide area.
Sedimentation occurs when water carrying eroded soil particles slows long enough to allow soil particles to settle out. The smaller the particle, the longer it stays in suspension. Larger, heavier particles such as gravel and sand settle out sooner than smaller, lighter particles such as clay. Clay may stay in suspension for very long periods, contributing significantly to water turbidity. By volume, sediment is the largest water pollutant in North Carolina.