Stormwater is a term used to describe water that originates during precipitation events. In Meteorology, precipitation (also known as one class of hydrometeors, which are atmospheric water phenomena is any product of the condensation of atmospheric It may also be used to apply to water that originates with snowmelt or runoff water from overwatering that enters the stormwater system. Stormwater that does not soak into the ground becomes surface runoff, which either flows into surface waterways or is channeled into storm sewers. Surface runoff is a term used to describe when soil is infiltrated to full capacity and excess Water, from Rain, Snowmelt, or other sources flows A storm drain, storm sewer ( US) stormwater drain ( Australia and New Zealand) or surface water system ( UK)
Stormwater is of concern for two main issues: one related to the volume and timing of runoff water (flood control and water supplies) and the other related to potential contaminants that the water is carrying, i. A flood is an overflow of an expanse of water that submerges land a deluge e. water pollution. Water pollution is the contamination of Water bodies such as Lakes Rivers Oceans and Groundwater caused by human activities
Since the era that humans began living in concentrated village or urban settings, stormwater runoff has presented itself as an issue. Such dwelling styles can be generally related to the Bronze Age when considerable amounts of impervious surface emerged as a factor in the design of early human settlements. The term Bronze Age refers to a period in human cultural development when the most advanced Metalworking (at least in systematic and widespread use included techniques for A settlement is a general term used in Archeology, Landscape history and other subjects for a permanent or temporary community in which people live which avoids being Some of the early incorporation of stormwater engineering is evidenced in ancient Greece. Greece (Ελλάδα transliterated: Elláda, historically, Ellás,) officially the Hellenic Republic (Ελληνική Δημοκρατία  An early specific example of stormwater runoff system design is found in the archaeological recovery at Minoan Phaistos on Crete. Archaeology, archeology, or archæology (from Greek grc ἀρχαιολογία archaiologia – grc ἀρχαῖος archaīos Phaistos (Φαιστός also transliterated as Phaestos, Festos and Phaestus is an ancient city on the Island of Crete Crete ( Greek: Κρήτη transliteration: Krētē, modern transliteration Kriti) is the largest of the Greek islands and the 
Because impervious surfaces (parking lots, roads, buildings, compacted soil) do not allow rain to infiltrate into the ground, more runoff is generated than in the undeveloped condition. Impervious surfaces are mainly artificial structures such as pavements rooftops sidewalks roads and parking lots - covered by impenetrable materials such as asphalt concrete Parking lot (called a car park in Australia and the UK) is a cleared area that is more or less level and is intended for Parking vehicles A road is an identifiable route, way or path between two or more places. In Architecture, Construction, Engineering and real estate development the word building may refer to one of the following Any man-made Soil compaction occurs when weight of Livestock or heavy machinery compresses Soil, causing it to lose Pore space Infiltration is the process by which water on the ground surface enters the Soil. This additional runoff can erode watercourses (streams and rivers) as well as cause flooding when the stormwater collection system is overwhelmed by the additional flow. A stream is a body of Water with a current, confined within a bed and stream-banks "Riverine" redirects here For the use of that term in Maritime geography, see there A flood is an overflow of an expanse of water that submerges land a deluge A storm drain, storm sewer ( US) stormwater drain ( Australia and New Zealand) or surface water system ( UK) Because the water is flushed out of the watershed during the storm event, little infiltrates the soil, replenishes groundwater, or supplies stream baseflow in dry weather. A drainage basin is an extent of Land where Water from Rain or Snow melt drains downhill into a body of water such as a River, Groundwater is Water located beneath the Ground surface in Soil pore spaces and in the Fractures of lithologic formations Baseflow is the portion of Streamflow that comes from Groundwater and not runoff.
Pollutants entering surface waters during precipitation events is termed polluted runoff. Daily human activities result in deposition of pollutants on roads, lawns, roofs, farm fields, etc. A road is an identifiable route, way or path between two or more places. A lawn is an area of recreational or amenity land planted with grass, and sometimes Clover and other plants which are maintained at a low even height Vietnam roofjpg|thumb|The roofs of Vietnam.]] A roof is the covering on the uppermost part of a Building. A farm is an area of land including various structures devoted primarily to the practice of producing and managing food ( Produce, Grains, or Livestock When it rains or there is irrigation, water runs off and ultimately makes its way to a river, lake, or the ocean. Rain is Liquid precipitation. On Earth it is the condensation of atmospheric Water vapor into drops heavy enough to fall often making it to Irrigation is an artificial application of water to the soil usually for assisting in growing crops Water is a common Chemical substance that is essential for the survival of all known forms of Life. "Riverine" redirects here For the use of that term in Maritime geography, see there A lake (from Latin lacus) is a Terrain feature (or Physical feature) a body of Liquid on the surface of a world that is localized to the An ocean (from Greek, ''Okeanos'' (Oceanus) is a major body of saline water, and a principal component of the Hydrosphere. While there is some attenuation of these pollutants before entering the receiving waters, the quantity of human activity results in large enough quantities of pollutants to impair these receiving waters
In addition to the pollutants carried in stormwater runoff research by Australian researchers is identifying urban runoff as a cause of pollution in its own right. In Physics, attenuation (in some context also called extinction) is the gradual loss in intensity of any kind of Flux through a medium Human beings, humans or man (Origin 1590–1600 L homō man OL hemō the earthly one (see Humus
In natural catchments surface run off entering waterways is a relatively rare event, occurring only a few times each year and generally after larger storm events. Before development occurred most rainfall soaked into the ground and contributed to groundwater recharge or was recycled into the atmosphere by trees as evapotranspiration.
Modern drainage systems which collect runoff from impervious surfaces (eg. roofs and roads) ensure that water is efficiently conveyed to waterways through pipe networks, meaning that even small storm events result in increased flows in our waterways.
In addition to delivering higher pollutants from the urban catchment increased stormwater flow can lead to stream erosion, encourage weed invasion and can alter natural flow regimes which native species rely on for a range for activities including spawning, juvenile development and migration.
Integrated water management (IWM) of stormwater has the potential to address many of the issues affecting the health of waterways and water supply challenges facing the modern urban city.
Also known as low impact development in the United States, IWM has the potential to improve runoff quality, reduce the risk and impact of flooding and deliver an additional water resource to augment potable supply. Low Impact Development (LID is a term used in the United States to describe a land planning and engineering design approach to managing Stormwater The United States of America —commonly referred to as the
The development of the modern city often results in increased demands for water supply due to population growth, while at the same time altered runoff predicted by climate change has the potential to increase the volume of stormwater that can contribute to drainage and flooding problems. IWM offers several techniques including stormwater harvest (to reduce the amount of water that can cause flooding), infiltration (to restore the natural recharge of groundwater), biofiltration or bioretention (e. An infiltration basin, is a type of best management practice (BMP that is used to manage Stormwater runoff, prevent Flooding and downstream Bioretention is the process of biological removal of contaminants or nutrients as fluid passes through media or a biological system g. rain gardens) to store and treat runoff and release it at a controlled rate to reduce impact on streams and wetland treatments (to store and control runoff rates and provide habitat in urban areas). A rain garden is a planted depression that is designed to absorb rainwater runoff from impervious urban areas like roofs driveways walkways and compacted lawn areas
IWM as a movement can be regarded as a in its infancy and brings together elements of drainage science, ecology and a realisation that traditional drainage solutions which utilise more efficent pipe networks transfer problems further downstream to the detriment of the health of our stressed environmental streams.
In the United States, the Environmental Protection Agency (EPA) is charged with regulating stormwater pursuant to the Clean Water Act (CWA). The United States of America —commonly referred to as the This article is for the legal term For regulation of genes see Regulation of gene expression. The Clean Water Act is the primary Federal law in the United States governing Water pollution.  The goal of the CWA is to restore all "Waters of the United States" to their "fishable" and "swimmable" conditions. Point source discharges, which originate mostly from municipal wastewater (sewage) and industrial wastewater discharges, have been regulated since enactment of the CWA in 1972. Distinguish from Wastwater (a lake in the Lake District in northwest England Sewage is the mainly liquid Waste containing some solids produced by humans which typically consists of washing water Feces, Urine, laundry waste and other This article is for the legal term For regulation of genes see Regulation of gene expression. Pollutant loadings from these sources are tightly controlled and limited. However, despite these controls, thousands of water bodies in the U. S. remain classified as "impaired," meaning that they contain pollutants at levels higher than is considered safe by EPA for the intended beneficial use of the water. Much of this impairment is due to polluted runoff.
Under the CWA, point source discharges to "Waters of the United States" require National Pollution Discharge Elimination System (NPDES) permits. The Clean Water Act is the primary Federal law in the United States governing Water pollution. To address the nationwide problem of stormwater pollution, in 1987 Congress broadened the CWA definition of "point source" to include industrial stormwater discharges and municipal separate storm sewer systems ("MS4"). The United States Congress is the bicameral Legislature of the federal government of the United States of America, consisting of two houses A storm drain, storm sewer ( US) stormwater drain ( Australia and New Zealand) or surface water system ( UK)  These facilities were required to obtain NPDES permits. This 1987 expansion was promulgated in two phases: Phase I and Phase II. Phase I required that all municipalities of 100,000 persons or more, industrial dischargers, and construction sites of 5 acres or more have NPDES permits for their stormwater discharges. A municipality is an administrative entity composed of a clearly defined territory and its population and commonly denotes a City, Town, or Village, or In the fields of Architecture and Civil engineering, construction is a process that consists of the Building or assembling of Infrastructure The acre is a unit of Area in a number of different systems including the imperial and U Phase I permits were issued in much of the U.S. in 1991. The United States of America —commonly referred to as the Phase II required that all municipalities, industrial dischargers, construction sites of 1 acre or more, and other large property owners (such as school districts) have NPDES permits for their stormwater discharges. A municipality is an administrative entity composed of a clearly defined territory and its population and commonly denotes a City, Town, or Village, or In the fields of Architecture and Civil engineering, construction is a process that consists of the Building or assembling of Infrastructure The acre is a unit of Area in a number of different systems including the imperial and U School districts are a form of Special-purpose district which serves to operate the local public primary and secondary schools Phase II rules came into effect in 2003.
On May 16, 2008 the EPA announced the issuance of a new Construction General Permit (CGP) to replace the permit that expires on July 1, 2008. This new permit has no substantive changes to the current Construction General Permit save the extension of the current conditions through July 1, 2010. 
EPA has authorized 45 states to issue NPDES permits.  In addition to implementing the NPDES requirements, many states and local governments have enacted their own stormwater management laws and ordinances, and some have published stormwater treatment design manuals. Some of these state and local requirements have expanded coverage beyond the federal requirements. For example, the State of Maryland requires erosion controls and sediment controls on construction sites of 5,000 sq ft (460 m²) or more. Erosion control is the practice of preventing or controlling wind or water Erosion in Agriculture, Land development and Construction. 
Agricultural runoff (except for concentrated animal feeding operations, or "CAFO") is considered by the CWA to be nonpoint source pollution. Factory farming is the practice of raising Farm animals in confinement at high stocking density where a farm operates as a Factory &mdash a practice typical in Nonpoint source (NPS pollution is Water pollution affecting a water body from diffuse sources rather than a point source which discharges to a water body at a single It is not included in the CWA definition of "point source" and therefore not subject to NPDES permit requirements. The 1987 CWA amendments established a non-regulatory program at EPA for nonpoint source pollution management consisting of research and demonstration projects. Related programs are conducted by the Natural Resources Conservation Service (NRCS) in the U. The Natural Resources Conservation Service (NRCS formerly known as the Soil Conservation Service (SCS is an agency of the United States Department of Agriculture S. Department of Agriculture.