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A Vegetated Treatment System (VTS) is an alternative to full containment of runoff for managing open lot runoff. As part of a multi-state effort to determine VTS alternative performance standards for large beef Concentrated Animal Feeding Operations, two sites in Nebraska were constructed and monitored for two years to determine performance. Feedlot #1 has 1700 head on 11.8 acres which gravity flows onto 9.5 acres of VTA and utilizes a settling bench for solids retention. Feedlot #2 has 1200 head on 11.8 acres of lots that drain into four settling basins, from which the runoff is pumped onto 11 acres, separated into eight distribution areas. VTA runoff is collected and returned to the settling basins. The VTAs are hayed once each summer to remove nutrients. ISCO water samplers were installed on each site and recorded water flow onto and off of the VTA's and samples were taken to determine nutrient concentrations of these flows. At feedlot #1, during 2008, 44,133 m3 of VTA discharge was recorded (10,904 kg N; 9,064 kg P). The following year, with an established grass stand and lower rainfall, 2,581 m3 was discharged (975 kg N; 768 kg P). At feedlot #2, in 2008, 26,795 m3 of lot runoff were applied to the VTAs (1,496 kg N, 46.9lb/ac-in; 1,053 kg P). Haying removed 865 kg N and 134 kg P. During 2009, 9,356 m3was applied with a 94% reduction in the VTA runoff volume (-94% N, -94% P). The nutrient concentrations in the feedlot runoff water pumped onto the VTA did not show any trends based on the volume pumped out of the basins. The volume of VTA runoff is linearly related to the mass of the runoff nutrients indicating that infiltration is the primary mechanism for nutrient reductions. At both sites vegetation stand establishment and soil infiltration were critical to VTS performance and increased throughout the sampling period.