Filter strips are bands of vegetation along streams or other bodies of water. They filter sediment and other pollutants from runoff water before the water enters streams, lakes, rivers and reservoirs. The vegetation is most often grass but in some cases trees are also planted to work with the grass. Their roots can absorb nutrients that might otherwise enter the water. The most effective filter strips are those established at the bases of gentle, even slopes that have fairly uniform, non-concentrated runoff from the slope. A filter strip, if wide enough, will slow runoff water enough that sediments settle out.

Filter strips do not take the place of upland soil conservation practices; they are the last line of defense to prevent contamination of water bodies. These areas of vegetation alongside watercourses also mean farming operations are kept farther away from water, which slows stream bank erosion and distances any chemicals from the water body.