Are water quality issues associated with subsurface drainage?
Where rainfall triggers tile flow events, the water that discharges from tile has some positive and negative quality aspects. Generally, phosphorus and sediment losses from tile drained fields are less than surface drained fields while loss of nitrogen in the form of nitrate and other dissolved minerals may increase. Tile drains installed to control salinity will discharge water containing higher total dissolved salts for several years with the concentration decreasing each year after installation. Eventually, the discharge will reach an equilibrium value.
NDSU Extension Ag and Biosystems Engineering in partnership with the North Dakota Department of Health, has conducted two tile drainage water-sampling projects. The first project, titled Phase 1 and completed in 2008, was to collect weekly water samples from 18 tile outlets to determine the water quality characteristics of tile drainage water.
The second project, titled Phase II, began in 2009 and was completed in 2013. The objective was to determine the concentration and loading rates of the outflow from recently installed tile on saline affected soils.
