Surface and subsurface water that leaves the field following application of irrigation water. While irrigation return flows are a " point source," they are expressly exempted from permit requirements under the Clean Water Act.
(1) That part of a diverted flow that is not consumptively used and returned to its original source or another body of water. (2) Irrigation water that is applied to an area and which is not consumed in evaporation or transpiration and returns to a surface stream or aquifer.
the water that reaches a ground- or surface-water source after release from the point of use and thus becomes available for further use.