SURFACE RUNOFF

That part of the runoff which travels over the soil surface to the nearest stream channel. It is also defined as that part of the runoff of a drainage basin that has not passed beneath the surface since precipitation. Also applies to snowmelt or irrigation water in excess of what can infiltrate the soil surface and be stored in small surface depressions. In terms of surface water quality, may constitute a major transporter of Non-Point Source (NPS) Pollution. The term is misused when applied in the sense of Direct Runoff. Also see Runoff, Direct Runoff, Overland Flow, Ground-Water Runoff, and Surface Water.