Natural Filter Strips:
An Ecological Approach to Pollutant Reduction in Water Bodies
Dr. Mario A. Villarino, County Extension Agent for Agriculture and Natural Resouces
A recent publication from Texas A&M Agrilife Extension Services entitled Lone Star Healthy Streams provides best management practices (BMPs) for dairies looking into reducing water contamination. The publication was created by the collaborative work of many entities interested in water conservation and protection. One particular part of the publication became very interesting to me after reviewing the different chapters and it was runoff management. Runoff management BMPs help reduce the amount of water moving across the landscape as well as the amount of pollutants being moved into water bodies. For grazing dairies, the primary BMP to manage runoff is filter strips (NRCS Code 393). A filter strip is an area of herbaceous vegetation that is established between a body of water and cropland, grazing land, or disturbed land. It is designed to remove sediment, bacteria, organic material, nutrients, and chemicals from overland water flow.
A filter strip works by slowing runoff, which allows the contaminants to settle out, infiltrate, and be dispersed across the width of the strip. In addition to protecting water quality, filter strips can also improve soil aeration, create wildlife habitat, provide shade that improves soil moisture content, recycle nutrients that promote plant growth, and help protect riparian areas. If riparian areas are protected from overstocking and overgrazing, they will naturally develop effective vegetative filter strips that further protect the stream from runoff containing bacteria, nutrients, pesticides, and sediment.
For adequate protection, filter strips should have specific minimum widths, which vary according to the slope of the land. The effectiveness of filter strips depends on the amount of sediment that reaches the filter strip and the amount of time that water is retained in the filter strip, among other technical requirements for the filter strip to become effective. For more information on filter strips or any other agricultural topic, please contact the Hopkins County Extension Office at 903-885-3443 or e-mail me at firstname.lastname@example.org