Best Management Practice (BMP) is a common term used to describe a structure or land management practice that filters or removes pollutants from stormwater runoff, slows the velocity of runoff, and/or reduces the volume of runoff. BMPs may be very large scale, such as those used to control stormwater from an entire community or a large scale development project. They may also be very small actions individuals can take to reduce their own impacts on stormwater runoff. Or, they may be any scale in between. Other terms used to describe BMPs are “conservation practices” or “stormwater management facilities” (the latter usually refers to the larger scale practices).
Some common BMPs include:
- Dry Detention Basin/Pond: Dry ponds are designed to hold water temporarily after a storm; no water will remain in it permanently if it is functioning properly.
- Wet Retention Basin/Pond: Wet ponds contain a permanent pool of water much like a lake.
- Biofilter/Bioretention Area (including rain gardens): Biofilters, bioretention areas, or “rain gardens” as they are often called, are shallow, vegetated depressions that store and treat stormwater runoff.
- Constructed Wetlands: The complex physical and biological environments of wetlands can improve water quality and provide flood control.
- Infiltration Practices: Infiltration practices use temporary surface or underground storage to allow incoming stormwater runoff to be absorbed by the soil. If soils have adequate permeability, infiltration practices can have the greatest runoff reduction capability of any stormwater practice.
- Sand Filter: Sand filters are stormwater practices that use sand to filter runoff.
- Grassed Swale: Grassed swales are concave, earthen conveyance systems designed to simply move water safely, or to provide water quality improvements through infiltration and the trapping of sediment particles in the ground cover.
- Manufactured Unit (also known as proprietary BMPs): Many companies have developed devices to improve the quality of stormwater runoff.
- Permeable Pavement: Permeable pavement is an alternative surface that allows stormwater to filter through to the soil below.
- Filter Strips, Stream Buffers, and Conserved Open Space: Natural areas of vegetation between a developed site and a waterway can protect water quality by filtering out pollutants and controlling the amount of runoff.
- Vegetated Roofs: A rooftop that is engineered to support plant growth can reduce pollutant loads, runoff volumes and flow rates of stormwater.
- Disconnected Impervious Areas: This is a simple practice that takes runoff from pavement or rooftops, and allows it to infiltrate into soil before it reaches a stormdrain or waterway.
- BMPs for your home: Everyone can help.
The effectiveness of any BMP is dependent on its maintenance.