Project ID



Subsurface drainage systems with surface inlets are widely used to divert water in crop producing areas, but pose problems because they can allow unfiltered, sediment-laden water to travel quickly to other waterways. The project tested several modest, uncomplicated inlet protection practices with potential to keep nutrient and sediment flows in check.

Key Question

Do surface inlets to tile drainage systems contribute to water quality problems in Iowa and are there viable alternative practices that can reduce their impact?


Current designs of surface inlets can allow water with high concentrations of sediment, sediment-bound phosphorus, and dissolved phosphorus to enter the drainage system. Blind inlets and filter socks amended with alum can reduce these concerns, but choosing the best practice to use will depend on site-specific conditions.

Principal Investigator(s)

Martin Shipitalo


Mark Tomer

Year of Grant Completion