Best management practice for water pollution

Best management practices (BMPs) is a term used in the United States and Canada to describe a type of water pollution control. Historically the term has referred to auxiliary pollution controls in the fields of industrial wastewater control and municipal sewage control, while in stormwater management (both urban and rural) and wetland management, BMPs may refer to a principal control or treatment technique as well. Beginning in the 20th century, designers of industrial and municipal sewage pollution controls typically utilized engineered systems (e.g. filters, clarifiers, biological reactors) to provide the central components of pollution control systems, and used the term "BMPs" to describe the supporting functions for these systems, such as operator training and equipment maintenance. Stormwater management, as a specialized area within the field of environmental engineering, emerged later in the 20th century, and some practitioners have used the term BMP to describe both structural or engineered control devices and systems (e.g. retention ponds) to treat polluted stormwater, as well as operational or procedural practices (e.g. minimizing use of chemical fertilizers and pesticides). Other practitioners prefer to use the term Stormwater control measure, due to the varied definitions of the term "BMP" and its use in non-stormwater practice. Congress referred to BMP in several sections of the U.S. Clean Water Act (CWA) but did not define the term. The 1977 CWA used the term in describing the areawide waste treatment planning program and in procedures for controlling toxic pollutants associated with industrial discharges. The "Section 404" program, which covers dredge and fill permits, refers to BMPs in one of the enforcement exemptions. References to stormwater BMPs first appear in the 1987 amendment to the CWA in describing the Nonpoint Source Management Demonstration Program. Another stormwater BMP reference was added in 2001 with the authorization for a Wet Weather Watershed Pilot Project program.