Glossary

• Base Flood is a flood having a 1% chance of being equaled or exceeded in any given year. Also referred to as the “100-year flood.”
• Base Flood Elevation (BFE) is the elevation of surface water resulting from a flood that has a 1% chance of equaling or exceeding that level in any given year. The BFE is shown on the Flood Insurance Rate Map (FIRM) for zones AE, AH, A1-A30, AR, AR/A, AR/AE, AR/A1-A30, AR/AH, AR/AO, V1-V30, and VE.
• Basement is any area of the building, including any sunken room or sunken portion of a room, having its floor below ground level (subgrade) on all sides.
• Best Management Practices (BMPs) are effective, practical, structural or nonstructural methods which prevent or reduce the movement of sediment, nutrients, pesticides and other pollutants from the land to surface or ground water, or which otherwise protect water quality from potential adverse effects of various land-use activities.
• Building is a structure with 2 or more outside rigid walls and a fully secured roof that is affixed to a permanent site; or a manufactured home; or a travel trailer without wheels, built on a chassis and affixed to a permanent foundation.
• Climate Change is defined as a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years.
• Combined Sewer is a type of sewer system that collects wastewater and stormwater in a single pipe.  These systems often get overwhelmed during precipitation events.
• Combined Sewer Overflows (CSOs) occur when a combined sewer system exceeds capacity and overflows into waterways.  These overflows contain not only stormwater but also untreated human and industrial waste, toxic materials, and debris. They are a major water pollution concern for the approximately 772 cities in the U.S. that have combined sewer systems.  Read more here.
• Community Rating System (CRS) is a program developed by FEMA to provide incentives for those communities in the Regular Program that have gone beyond the minimum floodplain management requirements to develop extra measures to provide protection from flooding.
• Concentrated Animal Feeding Operations (CAFOs) are agricultural operations where animals are kept and raised in confined situations.
• Dry Wells are a type of infiltration device, located underground that collect and infiltrates roof runoff at gutter downspouts, roof valleys, and other places where large amounts of concentrated water flow off of a roof.
• Electronic Waste (E-Waste) refers to discarded electronic devices.  In addition to lead, electronics can contain chromium, cadmium, mercury, beryllium, nickel, zinc and flame retardants. When electronics are not disposed of or recycled properly, these materials can cause environmental problems, including water pollution.
• Environmental Site Design (ESD), also referred to as Better Site Design (BSD),is an effort to mimic natural systems along the whole stormwater flow path through combined application of a series of design principles throughout the development site to replicate the natural landscape prior to development.
• Erosion is the collapse, undermining, or subsidence of land along the shore of a lake or other body of water.
• Evapotranspiration is the combination of water that leaves the soil through evaporation and transpiration from plants.
• Flood is a general and temporary condition of partial or complete inundation of 2 or more acres of normally dry land area or of 2 or more properties from: overflow of inland or tidal waters; or unusual and rapid accumulation of runoff of surface waters from any source; or mudflow; or collapse or subsidence of land along the shore of a lake or similar body of water as a result of erosion or undermining caused by waves or currents of water exceeding anticipated cyclical levels that result in a flood as defined above.
• Flood Insurance Rate Map (FIRM) is the official map of a community on which FEMA has delineated the Special Flood Hazard Areas (SFHAs), the Base Flood Elevations (BFEs), and the risk premium zones applicable to the community.
• Floodplain is any land area susceptible to being inundated by floodwaters from any source.
• Freeboard is an additional amount of height above the Base Flood Elevation used as a factor of safety in determined the level at which a structure’s lowest flood must be elevated or flood proofed to be in accordance with state or community floodplain management regulations.
• Green Infrastructure consists of site-specific management practices that are designed to maintain natural hydrologic functions by absorbing and infiltrating precipitation where it falls or utilizing natural systems that capture, cleanse and reduce stormwater runoff.
• Groundwater is water that is underground, stored in rock and soil.
• Household Hazardous Waste is leftover household products that contain corrosive, toxic, ignitable, or reactive ingredients are considered to be household hazardous waste (HHW).
• Illicit Discharge is any discharge to an MS4 that is not composed entirely of stormwater, except authorized non-stormwater discharges. Examples of illicit discharges include dumping of motor vehicle fluids, grass clippings and landscape debris, animal wastes, industrial waste/discharges, restaurant wastes, or any other non-stormwater waste. Illicit discharges can be accidental or intentional.
• Impervious Surfaces are surfaces that do not allow water to infiltrate.  Some examples of impervious surfaces are rooftops and paved roads.
• Increased Cost of Compliance (ICC) is coverage for expenses that a property owner must incur, above and beyond the cost to repair the physical damage the structure actually sustained from a flooding event, to comply with mitigation requirements of state or local floodplain management ordinances or laws.
• Infiltration devices drain or infiltrate water directly into the ground, providing opportunity for groundwater recharge. Infiltration facilities are below ground, and water should not appear on the surface after 24-48 hours following rainfall. Infiltration trenches and dry wells are example of infiltration devices.
• Lake is an inland body of standing water.
• Letter of Map Amendment (LOMA) is an amendment to the currently effective FEMA map which establishes that a property is not located in a Special Flood Hazard Area (SFHA). A LOMA is only issued by FEMA.
• Letter of Map Revision (LOMR) is an official amendment to the currently effective FEMA map. It is issued by FEMA and changes flood zones, delineations, and elevations.
• Load Allocation is the portion of surface water’s loading capacity that is assigned or allocated to existing and future nonpoint sources and natural quality.
• Low-Impact Development (LID) is a stormwater management approach that seeks to manage runoff by mimicking a site’s predevelopment hydrology by using design techniques that infiltrate, filter, store, evaporate, and detain runoff close to its source. LID preserves natural drainage features and patterns. For more information visit Low Impact Development Center.
• Lowest Adjacent Grade is the lowest point of the ground level immediately next to a building.
• Lowest Floor is the lowest floor of the lowest enclosed area (including a basement). An unfinished or flood-resistant enclosure, usable solely used for parking of vehicles, building access, or storage in an area other than a basement area, is not considered a building’s lowest floor provided that such enclosure is not built as to render the structure in violations of requirements.
• Municipal Separate Storm Sewer System (MS4) is all separate storm sewers that are defined as “large” or “medium” or “small” municipal separate storm sewer systems pursuant to 40 CFR §§ 122.26(b)(4), (b)(7), and (b)(16), respectively, or designated under 40 CFR § 122.26(a)(1)(v).
• Municipal Separate Storm Sewershed (MS3) is the land area draining to an individual MS4 outfall.
• Municipal Separate Storm Sewer is a conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels, or storm drains): (i) Owned or operated by a State, city, town, borough, county, parish, district, association, or other public body (created by or pursuant to State law) having jurisdiction over disposal of sewage, industrial wastes, stormwater, or other wastes, including special districts under State law such as a sewer district, flood control district or drainage district, or similar entity, or an Indian tribe or an authorized Indian tribal organization, or a designated and approved management agency under section 208 of the CWA that discharges to surface waters; (ii) Designed or used for collecting or conveying stormwater; (iii) Which is not a combined sewer; and (iv) Which is not part of a Publicly Owned Treatment Works (POTW) as defined at 40 CFR 122.2.
• National Flood Insurance Program (NFIP) is the program of flood insurance coverage and floodplain management managed under the National Flood Insurance Act of 1968 and applicable federal regulations promulgated in the Title 44 of the Code of Federal Regulations, Subchapter B.
• Non-Point Source Pollution is pollution that collects in small amounts from a variety of places.  Cumulatively, these small amounts often result in large amounts of pollution.  Stormwater picks up non-point source pollution as it moves across the land.  Examples of non-point source pollution are oil from cars, trash, and pesticides/fertilizers. 
• Outfall is a point source as defined by 40 CFR § 122.2 at the point where a municipal separate storm sewer discharges to surface waters and does not include open conveyances connecting two municipal separate storm sewers, or pipes, tunnels or other conveyances which connect segments of the same stream or other surface waters and are used to convey surface waters
• Pervious Surfaces allow water to infiltrate.  Some examples of pervious surfaces are un-compacted landscaping beds and pervious pavement. 
• Point source is a discernible, confined, and discrete conveyance, including, but not limited to, any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, Concentrated Aquatic Animal Production Facility (CAAP), Concentrated Animal Feeding Operation (CAFO), landfill leachate collection system, or vessel or other floating craft from which pollutants are or may be discharged.
• Point Source Pollution is pollution that is discharged from a single point, such as an oil spill.
• Pre-FIRM Building is a building for which construction or substantial improvement occurred after December 31, 1974 or on or after the effective date of an initial Flood Insurance Rate Map (FIRM), whichever is later.
• Post-FIRM Building is a building for which construction or substantial improvement occurred on or before December 31, 1974 or before the effective date of an initial Flood Insurance Rate Map (FIRM).
• Preferred Risk Policy (PRP) is a lower-cost Standard Flood Insurance Policy (SFIP) written under the Dwelling Form or General Property Form. The PRP is available for property located in B, C, and X Zones in Regular Program communities that meets eligibility requirements based on the property’s flood loss history.
• Rain Barrel is a device to collect rainwater from downspouts. Rain barrels can be bought in a store or made at home.
• Rain Garden is a landscaping feature that is planted with wild flowers and other native plants that stores and infiltrates water runoff from a roof, driveway, or other paved surface. The water slowly seeps into the ground instead of heading for the nearest storm drain.
• Repetitive Loss Structure is an NFIP-insured structure that has had a least 2 paid flood losses of more than $1,000 each in any 10-year period since 1978.
• River is a large natural stream of water emptying into an ocean, lake, or other body of water and usually fed along its course by converging tributaries.
• Runoff is water or snow melt that is not absorbed by soil during a precipitation event and flows into surface waters.
• Sanitary Sewer is a type of sewer system that is designed to collect only wastewater.  Where these sewer systems are present, stormwater is conveyed to local waterways in pipes designed exclusively for stormwater. 
• Separate Sewer Overflows (SSOs) occur when sanitary sewers exceed capacity and overflow.  EPA estimates that there are at least 23,000 – 75,000 SSOs per year (not including sewage backups into buildings). The untreated sewage from these overflows can contaminate our waters, causing serious water quality problems. It can also back-up into basements, causing property damage and threatening public health.  Read more at the EPA website.
• Severe Repetitive Loss Building is any building that 1) is covered under a Standard Flood Insurance Policy made available under this title; and 2) has incurred flood damage for which a) 4 or more separate claim payments have been made under an SFIP with the amount of each such claim exceeding $5,000, and with the cumulative amount of such claims payments exceeding $20,000; or b) at least 2 separate claims payments have been made under an SFIP, with the cumulative amount of such claim payments exceed the fair market value of the insured building on the day before each loss.
• Sheet flow is a type of flood with flooding depths of 1 to 3 feet that occurs in areas of sloping land. The sheet flow hazard is represented by the zone designation AO on the FIRM.
• Small Municipal Separate Storm Sewer System (Small MS4) is an MS4 that is not a large or medium MS4 pursuant to 40 CFR §§ 122.26(b)(4) and 122.26(b)(7). The term small MS4 includes systems similar to separate storm sewer systems in municipalities, such as systems at military bases, large hospital or prison complexes, and highways and other thoroughfares. The term does not include separate storm sewers in very discrete areas, such as individual buildings.
• Special Flood Hazard Area (SFHA) is an area having special flood, mudflow, or flood-related erosion hazards and shown on a Flood Hazard Boundary Map (FHBM) or a Flood Insurance Rate Map (FIRM) as Zone A, AO, A1-A30, AE, A99, AH, AR, AR/A, AR/AE, AR/AH, AR/AO, AR/A1-A30, V1-V30, VE, OR V.
• Stormwater is water that originates during precipitation events.
• Stormwater Management Program (SWMP) is the foundational program management tool for MS4 Permit facilitation; capturing the developed process, procedure, and implementation strategies for described elements (including MCMs). The primary purpose of the document is to present an integrated approach for reducing the discharge of pollutants from the MS4 to the Maximum Extent Practicable (MEP), to protect and improve the quality of water bodies, and adhere to the appropriate water quality standards requirements in the CWA
• Stormwater Pollution Prevention Program (SWPPP) is a compilation of BMPs to address the six minimum control measures of the MS4 permit that is designed to reduce the discharge of pollutants from your MS4 to the maximum extent practicable.
• Stormwater Runoff is generated when precipitation from rain and snowmelt events flows over land or impervious surfaces and does not percolate into the ground.
• Substantially Damaged Building is a building that has incurred damage of any origin whereby the cost of restoring the building to its before damaged condition would equal or exceed 50% of the market value of the building before the damage occurred.
• Substantially Improved Building is a building that has undergone reconstruction, rehabilitation, addition, or other improvement, the cost of which equals or exceeds 50% of the market value of the building before the “start of construction” of the improvement.
• Surface Water is any perennial and intermittent streams, rivers, lakes, reservoirs, ponds, wetlands, springs, natural seeps and estuaries, excluding water at facilities approved for wastewater treatment such as wastewater treatment impoundments, cooling water ponds and constructed wetlands used as part of a wastewater treatment process. (PADEP definition in MS4 permit – see Clean Water Act definition of “Waters of the United States”).
• Total Maximum Daily Load (TMDL) is maximum amount of a pollutant that can be discharged into a water body from all sources and still maintain water quality standards. Under CWA Section 303(d), TMDLs must be developed for all water bodies that do not meet water quality standards.
• Urban Forestry is the management of trees and plants or forested area located within a city or other urban area.
• Watershed is an area of land that drains precipitation (rain and snow) into a stream, river, wetland, lake or ocean.
• Write Your Own (WYO) Program is a cooperative undertaking of the insurance industry and FEMA begun in October 1983. The Write Your Own (WYO) Program operates within the context of the NFIP and involves private insurance carriers who issue and service NFIP policies.