Best Management Practices
Best management practices (BMPs) are effective practices that act to reduce the nonpoint pollution load in water systems and decrease the velocity of runoff after storm events. These practices are usually created and maintained for long-term use and coincide with the local water quality standards for a particular area. Selection and suitability of a BMP should be based on: site specific conditions, type of land use activity, the physical makeup of the watershed, and consideration of the pollutant(s) involved.
|Conservation Tillage and No-Till|
- Conservation tillage is an agricultural BMP that provides long-term crop residues and vegetation on croplands. This practice greatly reduces erosion and surface runoff of heavy metals and pesticides, which may reside in higher concentrations in the surrounding soil. No-plow is a similar practice that minimizes the spring influx of sediment into nearby waters by anchoring the soil to the plant root systems. Either way, by retaining crop residue and vegetative cover, this practice reduces time and energy on the farmer, it delays the warming and drying of the soil, and overall maintains a higher quality of soil.
|Contour strip cropping|
- Various rowcrops and hay in alternating strips planted side-by-side can reduce soil loss of about 50% compared to the same rotation contoured on its own. This practice is effective in that it provides rotated crops in different parts of the soil which act to strengthen the soil characteristics over time by not continually depleting the resource based on a monoculture. This process also decreases erosion and runoff and increases the stability of the local soil.
- Simple practices can be implemented to offset livestock impacts on nearby streams and rivers. By providing an alternative water source, for example, livestock would not be forced to wade in the streams and therefore would not be as likely to contribute to excess nutrient input from wastes. Large concentrations of wastes can speed up eutrophication of a stream, which will eventually decrease the effectiveness of the watershed's sustainability. Another effect of livestock in waterways is the increased potential for erosion by streambank deterioration from trampling and compaction. An alternative to better manage for the watershed could include creating a bridge to connect pastures where the animals can easily cross the stream without directly interacting with the water system.
Urban and Suburban
- Filter strips are wide areas of vegetation that act to intercept runoff. They can consist of any type of dense vegetation from woodlands to grass and can remove various pollutants, such as heavy metals, sediment loads, and excess organic materials.
Swales are shallow channel depressions where runoff flows. These swales slow the flow of the runoff water and allow particulates to settle out and water to infiltrate into the soil. These swales can effectively remove small amounts of excess nutrients and heavy metals.
- Constructed wetlands are often used in mitigation of other areas that lost wetlands due to development. Both natural and constructed wetland areas are saturated for sufficient time periods and are able to support unique vegetation adapted for life in such conditions. Wetlands are extremely efficient in filtering sediment, nutrients, and some heavy metals from storm water runoff and overflow of nearby water systems.
- Structures are often built in residential areas to alleviate stormwater runoff and retain or detain precipitation from storm events. Detention ponds are basins that temporarily store runoff from a site and release it at a controlled rate to minimize downstream flooding. These ponds are quite effective for pollutant removal, especially suspended sediments, if well designed.
- These trenches are shallow, usually three to eight feet deep, and backfilled with gravel to create underground reservoirs. Runoff, therefore, is diverted to the trenches and percolates into the subsoil. Such a practice effectively removes sediments and similar particles from stormwater runoff. This practice is commonly used in both commercial and residential areas.
- Construction sites, while under development, can implement many BMPs to reduce runoff, decrease pollutant loads to nearby water systems, and decrease the amount of soil washed from the site. Simple practices, such as setting up straw bales, silt fences, or even filter fabrics can act to slow runoff and retain sediment during storm events. Other practices, such as sediment basins to detain runoff or stabilizing entrances of construction, further decrease sediment and pollutant runoff.
- Citizens, commercial businesses, and even local and state agencies can implement and maintain efficient BMPs by taking the conservative approach to many everyday landscaping events. For example, sufficiently seeding grass to promote long-term stabilization of soil surfaces and planting wildflower cover (a practice used by many highway departments to provide aesthetically pleasing vegetation along roadways) greatly reduces the potential for erosion by securing the surfaces with plant roots. Other practices such as sodding and mulching can also be applied and have similar effective results.