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Storm Water - any water that flows during, or following, any form of natural precipitation, and is a result of such precipitation, including snow melt.
Watershed - land areas that catch rain or snow and drain to specific marshes, streams, rivers, lakes, or to ground water.
Best Management Practices (BMPs) - schedules of activities, prohibitions of practices, maintenance procedures, and other management practices to prevent or reduce the potential for storm water pollution. BMPs also include treatment requirements, operating procedures, and practices to control runoff, spillage or leaks, sludge or waste disposal, or drainage from raw material storage.
Contaminated - containing a harmful quantity of any substance.
Discharge - addition or introduction of any pollutant, storm water, or any other substance whatsoever into the municipal separate storm sewer system (MS4), into the Waters of the State, or into Waters of the United States.
Harmful Quantity - an amount of any substance that will cause pollution of the waters in the State, Waters of the United States, or that will cause sub-lethal adverse effects on representative, sensitive monitoring organisms upon their exposure to samples of any discharge into Waters in the State, Water of the United States, or the MS4.
Return to top of pageIllicit discharge - a discharge to an MS4 that is not entirely composed of storm water, except authorized discharges identified in the Storm Water Management Programs.
Major outfall - an outfall that discharges from a single pipe with an inside diameter of 36 inches or more, or its equivalent (discharge from a single conveyance other than a circular pipe which is draining an area greater than 50 acres.)
Maximum extent practicable - the technology-based discharge standard for MS4s to reduce pollutants in storm water discharges that was established by CWA §402(p). A more detailed discussion of MEP as it pertains to small MS4s can be found at 40 CFR 122.34.
Municipal separate storm sewer system (MS4) - the system of conveyances (including sidewalks, roads with drainage systems, County maintained streets, catch basins, curbs, gutters, ditches, man-made channels, or storm drains) owned and operated by the County and designed or used for collecting or conveying storm water, and which is not used for collecting or conveying sewage.
Return to top of pageNational Pollutant Discharge Elimination System (NPDES) - the national program for issuing, modifying, revoking and reissuing, terminating, monitoring and enforcing permits, and imposing and enforcing pretreatment requirements, under sections 307, 402, 318, and 405 of the federal Clean Water Act.
Non-point source pollution - any source of any discharge of a pollutant that is not a "point source."
Point source pollution - any discernible, confined, and discrete conveyance, including but not limited to, any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, concentrated animal feeding operation, landfill leachate collection system, vessel or other floating craft from which pollutants are or may be discharged. This term does not include return flows from irrigated agriculture or agricultural storm water runoff.
Pollutant - dredged spoil; solid waste; incinerator residue; sewage; garbage; sewage sludge; filter backwash; munitions; chemical wastes; biological materials; toxic materials; radioactive materials; heat; wrecked or discarded equipment; rock; sand; cellar dirt; and industrial, municipal, recreational, and agricultural waste discharged into water or into the municipal separate storm sewer system.
Pollution - the alteration of the physical, thermal, chemical, or biological quality of, or the contamination of, any Water of the State or Water of the United States, that renders the water harmful, detrimental, or injurious to humans, animal life, vegetation, or property, or to the public health, safety, or welfare, or impairs the usefulness or the public enjoyment of the water for any lawful or reasonable purpose.
Return to top of pageRelease - any spilling, leaking, pumping, pouring, emitting, emptying, discharging, injecting, escaping, leaching, dumping, or disposing into ground-water, subsurface soils, surface soils, the municipal separate storm sewer system (MS4), the Waters of the State, or the Waters of the United States.
Storm water pollution prevention plan (SWPPP or SWP3) - a plan required by a permit to discharge storm water associated with construction activity, and which describes and ensures the implementation of practices that are to be used to reduce the pollutants in storm water discharges associated with construction activity.
Texas Pollutant Discharge Elimination System (TPDES) - the program created for the State of Texas by TCEQ as agreed upon by the EPA pursuant to 33 USC §1342(b).
Uncontaminated - not containing a harmful quantity of any substance.
Wetland - an area that is inundated or saturated by surface or ground-water at a frequency and duration sufficient to support, and that under normal circumstances does support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas.
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Below you will find the defintions for 20 words commonly used in discussing storm water issues. It is not a complete list, but contains many of the more important, and lesser known terms.
Clicking on an underlined word will open a less technical description of the term.