The runoff and algae have increased with all the drain tiles installed in farm fields. Are these drains regulated?
The extensive tile and open drainage system that is in place in the flat lake plain portion of the Maumee River watershed has been in place for many years. In fact there are considerable less agricultural drainage tiles being installed the last several years than was installed during the 1970’s and earlier. The key nutrient that is being identified as contributing factor in the increase of algae blooms is phosphorus. Research results indicate that phosphorus is primarily transported in surface water and sediment runoff rather than through underground tile drains. However, if surface water enters a tile drain through a direct opening then, of course, the tile drain would transport it to its outlet.
The installation of tile drainage on private land is not regulated like a "point source" of pollution and does not require a National Pollution Discharge Elimination System (NPDES) Permit like for example a discharge pipe from an factory city sewage treatment plant does. There are thousands and thousands of tile drainage outlets and monitoring every single one is impossible and impractical. However, private tile drainage installation must comply with federal legislation that prohibits the use of drainage to convert wetlands to agricultural cropland and must also comply with the state drainage laws established in each state within the basin.
Tile drainage can actually reduce runoff in certain conditions by improving crop growth and soil tilth. Untiled fields can become saturated quicker resulting in more surface runoff, erosion and more transport of sediment and nutrients in surface runoff. Admittedly, tile flow can be a source of transport for nitrogen and dissolved runoff. That is why farmers and agricultural researchers are developing conservation practices to use "controlled drainage" to shut off tile and manage runoff during the non growing season when the tile are not needed.
Jim Lake, IN State Department of Agriculture