FAQ's/Glossary
Glossary of Common Watershed Protection and Stormwater Pollution Prevention Terms
Backfill
Earth refilling a trench or an excavation
Berm
An earthen mound used to direct flow of runoff around or through a structure.
Buffer strip or zone
Strip of erosion-resistant vegetation between a waterway and an area of more
intensive land use.
Catch Basin
Curbside opening that collects rainwater from streets and serves as an entry
point to the storm drain system.
Conduit
Any pipe for collecting and directing storm water.
Conveyance system
Any channel or pipe for collecting directing storm water.
Culvert
A covered channel or a large-diameter pipe that directs water flow below ground
level.
Denuded
Land stripped of vegetation or land that has had its vegetation worn down due
to the impacts from the elements or humans.
Discharge
The release of storm water or other substance from a conveyance system or storage
container
Erosion
The wearing away of land surface by wind or water. Erosion occurs naturally
from weather or runoff but can be intensified by land-clearing practices
related to farming, residential or industrial development, road building,
or timber-cutting.
Excavation
The process of removing earth, stone, or other materials, usually by digging.
Filter fabric
Textile of relatively small mesh or pore size that is used to (a) allow water
to pass through while keeping sediment out (permeable), or (b) prevent both
runoff and sediment from passing through (impermeable).
First flush
The first big rain after an extended dry period (usually summer) which flushes
out the accumulated pollutants in the storm drain system and carries them
straight to the ocean.
Grading
The cutting and/or filling of the land surface to a desired slope or elevation.
Gutter
The edge of a street (below the curb) designed to drain water runoff from the
streets, driveways, parking lots, etc. into catch basins.
Hazardous substance
1. Any material that poses a threat to human health and/or environment. Typical
hazardous substances are toxic, corrosive, ignitable, explosive, or chemically
reactive. 2. Any substance named by EPA to be reported is a designated quantity
of the substance is spilled in the waters of the United States or if otherwise
emitted into the environment.
Household hazardous waste
Common everyday products that people use in and around their homes - including
paint, paint thinner, herbicides, and pesticides - that, due to their chemical
nature, can be hazardous if not properly disposed. Illegal discharge Any
activity or event which results in a release, leak, flow, escape or the placement
of any material other than rain water (including liquids or solids) into
the storm drain system.
Illicit connection
Any connection to the storm drain system that is not permitted: or any legitimate
connection that is used for illegal discharge. Inlet An entrance into a ditch,
storm drain, or other waterway.
Illicit discharge
Any activity or event that results in a release, flow, spill, escape or disposal
of any material other than rainwater (including liquids or solids) into the
storm drain system.
Material storage areas
On site locations where raw materials, products, final products, by-products,
or waste materials are stored.
Non-point source pollution
Pollution that does not come from a single, identifiable source. Includes materials
that wash from roofs, streets, yards, driveways, sidewalks and other land
areas. Collectively, this is the largest source of stormwater pollution.
Non-stormwater discharge
Any discharge to municipal separate storm sewer that is not composed entirely
of storm water. Discharges containing process wastewater, non-contact cooling
water, or sanitary wastewater are non-storm water discharges.
Oil sheen
A thin, glistening layer of oil on water.
Organic pollutants
Substances containing carbon which may cause pollution problems in receiving
waters.
Organic solvents
Liquid organic compounds capable of dissolving solids, gases, or liquids.
Outfall
A flow of water from one drainage system into a larger system, or into a body
of water like a lake, bay, or the ocean.
Permeability
The quality of a soil that enables water or air to move through it. Usually
expressed in inches/hour or inches/day.
Point-source pollution
Pollution from a single identifiable source such as a factory or a sewage-treatment
plant. Most of this pollution is highly regulated at the state and local
levels.
Pollutant
Generally, any substance introduced into the environment that adversely affects
the usefulness of a resource.
Precipitation
Any form of rain or snow.
Retention
The storage of storm water to prevent it from leaving the development site;
may be temporary or permanent
Runon
Off-site flows which flows onto your site.
Runoff
Water originating from rainfall and other sources (e.g., sprinkler irrigation)
that is found in drainage facilities, rivers, streams, springs, seeps, ponds,
lakes, wetlands, and shallow groundwater.
Scour
The erosive and digging action in watercourse by flowing water.
Secondary containment
Structures, usually dikes or berms, surrounding tanks or other storage containers
and designed to catch spilled material from the storage containers.
Sedimentation
The process of depositing soil particles, clays, sands, or other sediments
that were picked up by runoff.
Sediments
Soil, sand, and minerals washed from land into water usually after rain, that
pile up in reservoirs, rivers, and harbors, destroying fish-nesting areas
and clouding the water so that needed sunlight might not reach aquatic plants.
Careless farming, mining, and building activities will expose sediment materials,
allowing them to be washed off the land after rainfalls.
Significant materials
Include, but not limited to, raw materials; fuels; materials such as solvents,
detergents, and plastic pellets; finished materials such as metallic products;
raw materials used in food processing or production; hazardous substances
designed under Section 101(4) of CERLCA; any chemical the facility is required
to report pursuant to Section 313 of Title III or SARA; fertilizers; pesticides;
and waste products such as ashes, slag and sludge that have the potential
to be released with storm water discharges.
Significant quantities
The volume, concentrations, or mass of a pollutant in storm water discharge
that can cause or threaten to cause pollution, contamination, or nuisance,
that adversely impact human health or the environment, and cause or contribute
to a violation of any applicable water quality standards for the receiving
water.
Source control
Action to prevent pollution where it originates.
Source control BMPs
Everyday operational practices that prevent pollution by reducing potential
pollutants at the source.
Spill guard
A device used to prevent spills of liquid materials from storage containers.
Storm drain system
A vast network of pipes and open channels designed for flood control, which
discharges straight to the ocean.
Stormwater
Precipitation that enters the storm drain system and empties into lakes, rivers,
streams or the ocean.
Stormwater pollution
Water from rain, irrigation, garden hoses or other activities that picks up
pollutants (cigarette butts, trash, automotive fluids, used oil, paint, fertilizers
and pesticides, lawn and garden clippings and pet waste) from streets, parking
lots, driveways and yards and carries them through the storm drain system
and straight to the ocean.
TMDLs - Total Maximum Daily Loads
A TMDL sets a limit for the total loading of a particular pollutant, such that
the pollutant loads from all sources will not impair the beneficial uses
designated for the water body.
Watershed
An area of land that drains water or runoff to a single point. For example,
the watershed of the Ventura River would be the surrounding neighborhoods
and natural terrain.
