ASAE/ASABE EP479.1 (R2023)

This Engineering Practice is intended as a guide for the design, installation and operation of a drainage system and head control structures whose purpose is the efficient management of the free water surface in the soil for drainage. This Engineering Practice is limited to systems utilizing pipe drains or open ditches to effect artificial subsurface drainage.

Water management systems, when operated in a drainage mode, have the potential of improving surface water quality by increasing soil water storage available for infiltration thereby reducing runoff that may carry sediment and undesirable chemicals. When operated in the controlled drainage mode, reduction in drainage depth or volume may occur, thereby reducing nutrient export, specifically nitrate-nitrogen. In open ditch systems, reduction in phosphorus loss can occur due to sedimentation in the channel upstream of the control structure.