Click here for a list of commonly used abbreviation/acronyms associated with the topic of Stormwater.

Aquifer – a geological formation, group of formations, or part of a formation that is capable of yielding potentially usable quantities of potable water from wells or springs.

Berm - a mound of soil, either natural or manmade.

Bioretention cells — shallow, landscaped depressions that can handle large volumes of water.

Bioswales — storm water conveyance features that slowly convey water to storm sewer inlets or surface waters and filter the initial runoff.

Clearing – the alteration of a site from its pre-development natural condition.

Closed Basin – an internally drained watershed in which the runoff does not have a surface outfall up to and including the 100-year flood elevation.

Design Flow – the flow of water in a pipe when either half full or full and expressed in gallons per minute, gallons per day, or cubic feet per second.

Developer – person, firm, or corporation engaged in developing or improving real estate for use or occupancy.

Drainage Basin or Watershed Basin – the area of land from which water drains into rivers, lakes, or other systems, including man made drainage facilities.

Drainage Facility – any pipe, ditch, retention area, etc., which stormwater flows through.

Drainage Retention Area (DRA), or Water Retention Area (WRA) – A reservoir which provides temporary storage of storm water runoff and disposes of same by soil percolation.

Drainage System – the system through which water flows from the land, including all drainage facilities, DRA’s WRA’s, swales, etc.

Equivalent Stormwater Unit (ESU) – the standard unit used to express the stormwater burden expected to be generated by each parcel of property. The average impervious area of single-family residential properties, in Marion County, is 2,275 square feet.

Flooding – a natural and recurring event for a rivers, lakes, streams, or ponds.  Flooding is a result of heavy or continuous rainfall exceeding the absorptive capacity of soil and the flow capacity of rivers, streams, and coastal areas. This causes a watercourse to overflow its banks onto adjacent lands.

Floodplains – in general, those lands most subject to recurring floods, situated adjacent to rivers, lakes, streams, ponds or localized depressions.

100-year Floodplain – areas around rivers, streams, ponds, lakes or localized depressions, at an elevation having a 1% chance of flood waters equaling or exceeding it each year,  as delineated in a flood insurance study for Flood Insurance Rate Maps for Marion County, FL.

Geotechnical/Soils Engineer – a Registered Florida Engineer who provides services related to terrain evaluation and site selection, subsurface exploration and sampling, determination of soil and rock properties, foundation engineering, settlement and seepage analysis, design of earth and earth retaining structures, the design of subsurface drainage systems and the improvement of soil properties and foundation conditions, and testing and evaluation of construction materials.

Green Space – parcel or area of land which is developed, planted, and maintained with trees, shrubs, ground covers or grass or a combination thereof, and is reserved for a yard area, landscape area, public or private park or recreation area, drainage retention areas and other similar areas.

Impervious Area – hard surfaced areas that do not absorb water, severely restrict the absorption of water and/or cause water to run off.  Common examples include parking lots, roofs, driveways, patios, sidewalks, etc.

Open Basin – all watersheds not meeting the definition for "closed basin".

Percolation – seepage of water through the soil under gravity.

Pervious Paving — surfaces, including permeable paver blocks, porous concrete, or porous asphalt. They provide the support of traditional parking surfaces, but they allow a significant amount of annual precipitation to be filtered.

Pollutant – chemicals and other materials that degrade the quality of water.  Common water pollutants are motor oils and other fluids, sewage, animal wastes, fertilizers, and other materials that may be collected by stormwater.

Pollution Abatement – methods and practices used to reduce or eliminate pollution of water bodies.

Potable Water — used for drinking, cooking, and domestic purposes. 

Rain Garden — native, perennial gardens strategically located to capture stormwater runoff. Potential benefits: increase aesthetic value, absorb water, reduce runoff, protect water quality and prevent flooding.

Retrofitting – designing and constructing improvements to an existing stormwater facility in order to meet the new NPDES and/or TMDL requirements.

Storm Frequency – the time interval in years in which a storm of given magnitude is expected to recur.

Stormwater – the flow of water which results from, and which occurs following, a rainfall event.

Stormwater Assessment – a stormwater improvement assessment, a stormwater service assessment, or both.

Stormwater Management – the intentional capture, placement, or movement of stormwater runoff in order to minimize pollution and/or flooding.

Stormwater Master Plan – a policy document which may be adopted by the board, as a part of the county's overall stormwater management program, which identifies the levels of service for water quality and quantity management in the county, based upon the criteria in the comprehensive plan and applicable state and federal law, and the methods for prioritizing expenditures within the county. The stormwater master plan shall designate those stormwater basins for which a stormwater basin plan will be prepared.

Stormwater Outfall – point where stormwater exits from a controlling device, such as a culvert, into a swale, retention area, lake or river.

Stormwater runoff – the flow of water that results from and occurs following a rainfall event.  As it travels across fields, yards, roads, etc., it will pick up a variety of pollutants and litter along the way.

Swale – a manmade, shallow ditch which can contain standing or flowing water for less than 72 hours following a rainfall event.

Total Maximum Daily Loading (TMDL) – a standard to meet for a specific pollutant such as nitrogen or phosphorus.

Water Detention Basin – manmade or natural water collection facility which collects surface or subsurface water and which impedes its flow and releases the same gradually at a rate not greater than that prior to the development of the property, into natural or manmade outlets.

Water Retention Area (WRA), or Drainage Retention Area (DRA) – A reservoir which provides temporary storage of storm water runoff and disposes of same by soil percolation.

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