“…Federal guidelines allow for the use and evaluation of VTS as an alternative to runoff retention ponds (Bond et Passive, gravity-based systems have been proposed as a cost-effective alternative for larger feedlots (Woodbury et al, 2003). Active systems have also been proposed and evaluated that include valves, pumps, or sprinkler systems to manage and apply runoff to the vegetated areas (Bond et al, 2010;Henry, 2007, 2010;Koelsch et al, 2006;Melvin and Lorimor, 2007;Moody et al, 2006;Ostrem et al, 2010;Powers et al, 2010) Berry et al (2007) evaluated a passive, gravity-fed brome grass VTS and found that bacterial and protozoal pathogen numbers generally declined over time, although some manure-borne bacteria were able to survive in the soil for extended periods. Andersen et al (2013) evaluated the performance of six commercial VTS in Iowa for nutrient parameters; however, microbial data were not collected in that study.…”