Grass Filter Strip
Grass filter strip protecting a stream from agricultural runoff. Photo courtesy USDA NRCS.
Setback distances for Minnesota shoreland rules, atrazine use and manure application. Diagram courtesy of the Cannon River Watershed Partnership.
Birdseye view of an agricultural landscape with grass filter strips and other types of conservation buffers. Photo courtesy USDA NRCS.
Grass Filter Strips are planted strategically between fields and surface waters (rivers, streams, lakes and drainage ditches) to protect water quality. They slow runoff from fields, trapping and filtering sediment, nutrients, pesticides and other potential pollutants before they reach surface waters. They can also be planted around drainage tile inlets for the same purpose.
Grass filter strips are especially important in Minnesota, which has more surface water than any of the 48 contiguous states. Grass filter strips can also help protect groundwater when planted around sinkholes (common in the karst regions of southeastern Minnesota) or in wellhead protection areas.
Grass filter strips in Minnesota typically range from 20 to 120 feet wide, depending on site characteristics, landowner goals, applicable regulations and voluntary conservation program requirements. Wider filter strips provide greater wildlife habitat benefits. Ongoing management of grass filter strips is needed to maintain the health of the vegetation and to repair rills running through the strip or channels that may develop along the edges.
Grass filter strips are useful in meeting Minnesota laws regarding vegetative buffers along streams and drainage ditches in agricultural areas. Minnesota drainage laws require a minimum 16.5 foot (1 rod) buffer strip along public drainage ditches. (Individual counties may require a wider buffer.) Minnesota shoreland management rules require a minimum 50-foot wide buffer on agricultural land in shoreland areas adjacent to designated public waters. (Shoreland areas include land within 1,000 feet of lakes or 300 feet of perennial rivers and streams.)
Grass filter strips are also useful in meeting manure application setback requirements in the Minnesota feedlot rules and Minnesota Department of Agriculture best management practice recommendations for herbicide and pesticide use. Setbacks may be mandatory when using products that contain the herbicide atrazine.
Whereas upland erosion and runoff control practices such as conservation tillage, cover crops, rotational grazing and nutrient and pest management are the first defense for minimizing the amount of sediment, nutrients and pesticides leaving farm fields, grass filter strips provide a second defense against water pollution by trapping and filtering pollutants that do leave the field, before they reach a river, lake or stream.
Grass filter strips involve grass planting and often go hand in hand with streambank & lakeshore protection and livestock exclusion/access control.
Once established, grass filter strips require ongoing grassland management.
Other similar or related practices covered in this Conservation Funding Guide include feedlot/wastewater filter strips, grass waterways, contour buffer strips, field borders and forested riparian buffers.
Guidance from USDA's Natural Resources Conservation Service (NRCS)
See Grass Planting and Grassland Management resources also.
Minnesota has long been a leading state in grass filter strip acreage established through federal programs. For details see:
See contacts for specific programs that fund this practice in the side-by-side payment comparison or contact your local Soil and Water Conservation District.