Sedimentation - A solid-liquid separation process utilizing gravitational settling to remove soil or rock particles from the water column .
SSO ( sanitary sewer overflow ) - Wastewater entering sanitary sewers may be so great , because of blockage , a lack of capacity , inflow and infiltration , or other reasons , that the collection system or sewage treatment plant cannot handle the increased flow . As a result , untreated sewage empties directly into receiving waters , often from manholes or up through sewer connections .
Storm sewer system - A system of pipes and channels that carry stormwater runoff from the surfaces of building , paved surfaces , and the land to discharge areas .
Stormwater - Water derived from a storm event or conveyed through a storm sewer system .
Stormwater utility - A utility established to generate a dedicated source of funding for stormwater pollution prevention activities where users pay a fee based on land-use and contribution of runoff to the stormwater system .
Surface water - Water that flows across the land surface , in channels , or is contained in depressions on the land surface ( e . g . runoff , ponds , lakes , rivers , and streams ).
Swale - A natural or human-made open depression or wide , shallow ditch that intermittently contains or conveys runoff . Can be used as a BMP to detain and filter runoff .
Total maximum daily load ( TMDL ) - The maximum allowable loading of a pollutant that a designated water body can assimilate and still meet numeric and narrative water quality standards . TMDLs were established by the 1972 Clean Water Act
Urban ( metropolitan ) runoff - Runoff derived from urban or suburban land-uses that is distinguished from agricultural or industrial runoff sources .
Water ( hydrologic ) cycle - The flow and distribution of water from the sky , to the Earth ' s surface , through various routes on or in the Earth , and back to the atmosphere . The main components are precipitation , infiltration , surface runoff , evapotranspiration , channel and depression storage , and groundwater .
Water quality - The biological , chemical , and physical condition of a waterbody ; a measure of the ability of a waterbody to support beneficial uses .
Watershed - The land area , or catchment , that contributes water to a specific waterbody . All the rain or snow that falls within this area flows to the waterbodies as surface runoff , in tributary streams , or as groundwater .
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