Much of the upper Midwest and 1/3 of Iowa is under tile drainage management. Subsurface tile drainage systems (often equipped with surface intakes) remove excess water from the land and improve the crop production in areas with hydric soils. However, these systems also have the potential to convey pollutants directly to nearby surface waters. When agricultural lands are amended with animal manures, there is concern of pathogen export as well as nutrient loading to downstream waters. One emerging technology for nitrate removal from subsurface waters is the woodchip bioreactor. These reactors are popular with farmers because of their edge-of-field treatment capabilities which do not require changes in land management practices. However, to date, limited research has been conducted to study the potential of these bioreactors to also reduce downstream transport of contaminants commonly detected in manure amended cropland, including pathogens and phosphorous. A 50% reduction in E. coli levels was observed in a single season of field sampling in Minnesota (K. Kult, Personal communication, 10 May 2013). Wide variations have also been reported regarding the potential for phosphorous removal by woodchip bioreactors (Ranaivoson et al., 2012). Potential filters using agents designed to adsorb P (limestone, steel shavings or slag, and gypsum, zeolites) have been described (King et al., 2010), but few studies have examined these in combination with woodchips.