This work included the in situ testing, laboratory characterization, and performance monitoring of biofilters amended with standard and alternative medias. Testing identified pertinent physical and water transport qualities of media that was compared between the methods to evaluate the predictive capacity of laboratory testing. Performance monitoring included a pilot test plot comparing compost and peat amended biofilters and a newly constructed peat biofilter. Field and laboratory testing revealed a range of performance in existing biofilters but did not indicate over or under performance of biofilters amended with alternative medias. The results of the two methods showed promise for the use of laboratory methods in predicting field performance. The monitoring at the pilot plot showed comparable infiltration capabilities between peat and compost. Both biofilters showed the ability to capture first flush rainfall events. The pilot plots showed clear impacts on infiltration efficiency based on initial soil moisture content and the duration of storm events. The newly constructed biofilter experienced similar impacts but also showed promise in meeting stormwater infiltration requirements.