Open feedlots are a common component of Midwestern animal agriculture, providing an economical option for the feeding and raising of livestock. However, open lot effluent, if not properly treated, can contribute to environmental pollution. Filterstrips are designed to treat open lot runoff by reducing concentrations of nutrients and sediment, which mitigates potential environmental impacts. The goals of this study are to (1) determine the ability of a filterstrip to attenuate pollutants, and (2) investigate the effect 20 years of filterstrip operation has on soil physical and chemical properties. Filterstrip treatment performance was determined by analyzing water samples entering and exiting the filterstrip. Water samples were collected and water volume determined using USGS gauging stations. Samples were analyzed for the following: total solids, suspended solids, nitrate-N, ammonium-N, total-N, organic-N, dissolved reactive phosphorus, and total phosphorus. Treatment performance was based on percent removal for each of the above constituents. The effect of filterstrip operation on soil chemical and physical properties was investigated by collecting and analyzing soil samples from the filterstrip and adjacent soils not impacted by the open lot effluent. Soil cores (12) were collected to a depth of 1 meter and divided into 10 cm segments prior to analysis. Samples were analyzed for the following: organic matter, pH, phosphorus, potassium, total nitrogen, ammonium-N, nitrate-N, chloride, and particle size. Research was conducted at U.W.-Platteville's Pioneer Farm. Keywords: filterstrip, open-lot, runoff, manure, dairy, feedlot.