Beginning in the 20th century, designers of industrial and municipal sewage pollution controls typically utilized engineered systems 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 to treat polluted stormwater, as well as operational or procedural practices. 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.
EPA definitions
In implementing the CWA, the U.S. Environmental Protection Agency defined BMP in the federal wastewater permit regulations, initially to refer to auxiliary procedures for industrial wastewater controls. Later the Agency added a reference to stormwater management BMPs.
Industrial wastewater BMPs
Industrial wastewater BMPs are considered an adjunct to engineered treatment systems. Typical BMPs include operator training, maintenance practices, and spill control procedures for treatment chemicals. There are also many BMPs available which are specific to particular industrial processes, for example:
management BMPs are control measures taken to mitigate changes to both quantity and quality of urban runoff caused through changes to land use. Generally BMPs focus on water quality problems caused by increased impervious surfaces from land development. BMPs are designed to reduce stormwater volume, peak flows, and/or nonpoint source pollution through evapotranspiration, infiltration, detention, and filtration or biological and chemical actions. BMPs also can improve receiving-water quality by extending the duration of outflows in comparison to inflow duration, which dilutes the stormwater discharged into a larger volume of upstream flow. Stormwater BMPs can be classified as "structural" or "non-structural". There are a variety of BMPs available; selection typically depends on site characteristics and pollutant removal objectives. EPA has published a series of stormwater BMP fact sheets for use by local governments, builders and property owners. Stormwater management BMPs can be also categorized into four basic types:
