Best management practices

Best management practices (BMPs) are methods that have been determined to be the most effective and practical means of preventing or reducing non-point source pollution to help achieve water quality goals. BMPS include both measures to prevent pollution and measures to mitigate pollution.

BMPS for agriculture focus on reducing non-point sources of pollution from croplands and farm animals. Agricultural runoff may contain nutrients, sediment , animal wastes, salts, and pesticides. With conservation tillage , crop residue, which is plant residue from past harvests, is left on the soil surface to reduce runoff and soil erosion , conserve soil moisture, and keep nutrients and pesticides on the field. Contour strip farming, where sloping land is farmed across the slopes to impede runoff and soil movement downhill, reduces erosion and sediment production. Managing and accounting for all nutrient inputs to a field ensures that there are sufficient nutrients available for crop needs while preventing excessive nutrient loading , which may result in leaching of the excess nutrients to the ground water. Various BMPs are available for keeping insects, weeds, disease, and other pests below economically harmful levels. Conservation buffers, including grassed waterways, wetlands , and riparian areas act as an additional barrier of protection by capturing potential pollutants before they move to surface waters. Cows can be kept away from streams by streambank fencing and installation of alternative water sources. Designated stream crossings can provide a controlled crossing or watering access, thus limiting streambank erosion and streambed trampling.

Coastal shorelines can also be protected with BMPs. Shoreline stabilization techniques include headland breaker systems to control shoreline erosion while providing a community beach. Preservation of shorelines can be accomplished through revegetation, where living plant materials are a primary structural component in controlling erosion caused by land instability.

Stormwater management in urban developed areas also utilize BMPs to remove pollutants from runoff. BMPS include retention ponds, alum treatment systems, constructed wetlands, sand filters , baffle boxes, inlet devices, vegetated swales, buffer strips, and infiltration/exfiltration trenches. A storm drain stenciling programs is an educational BMP tool to remind persons of the illegality of dumping litter, oil, pesticides, and other toxic substances down urban runoff drainage systems.

Logging activities can have adverse impacts on stream water temperatures, stream flows, and water quality. BMPS have been developed that address location of logging roads, skid trails, log landings and stream crossings, riparian management buffer zones, management of litter and fuel and lubricant spills, and reforestation activities.

Successful control of erosion and sedimentation from construction and mining activities involves a system of BMPs that targets each stage of the erosion process. The first stage involves minimizing the potential sources of sediment by limiting the extent and duration of land disturbance to the minimum needed, and protecting surfaces once they are exposed. The second stage of the BMP system involves controlling the amount of runoff and its ability to carry sediment by diverting incoming flows and impeding internally generated flows. The third stage involves retaining sediment that is picked up on the project site through the use of sediment-capturing devices. Acid drainage from mining activities requires even more complex BMPs to prevent acids and associated toxic pollutants from harming surface waters.

Other pollutant sources for which BMPS have been developed include atmospheric deposition , boats and marinas, habitat degradation, roads, septic systems, underground storage tanks, and wastewater treatment.

[Judith L. Sims ]

RESOURCES

BOOKS

Urban Water Infrastructure Management Committee. A Guide for Best Management Practice (BMP) Selection in Urban Developed Areas. Reston, VA: American Society of Civil Engineers, 2001.

U.S. Environmental Protection Agency.NPDES Best Management Practices Manual. Rockville, MD: Government Institutes, ABS Group, Inc., 1995.

OTHER

Logging and Forestry Best Management Practices. Division of Forestry, Indiana Department of Natural Resources. May 30, 2001. [June 15, 2002]. <http://www.state.in.us/dnr/forestry/bmp/logindex.htm>

Best Management Practices (BMPs) for Agricultural Nonpoint Source Pollution Control. North Carolina State University Water Quality Group. June 15, 2002. [June 17, 2002]. http://h2osparc.wq.ncsu.edu/info/bmps_for_ agnps.html

Best Management Practices (BMPs) for Non-Agricultural Nonpoint Source Pollution Control: Nonpoint Source Pollution Control Measures—Source Categories. North Carolina State University Water Quality Group. June 15, 2002. [June 17, 2002]. <http://h2osparc.wq.ncsu.edu/info/bmps.html>