Stormwater Glossary
City of Leavenworth, KS – Stormwater Glossary
This glossary provides clear definitions of terms commonly used in stormwater management, water quality, and drainage systems as they apply to the City of Leavenworth, Kansas. Its purpose is to help residents, developers, and city staff better understand the language of stormwater regulations, infrastructure, and practices. Many of these terms—such as detention basins, catch basins, BMPs (Best Management Practices), and watersheds—are directly connected to local features, including Leavenworth’s creeks (Three Mile Creek, Five Mile Creek, and the Missouri River). By using this glossary, the community can gain a clearer picture of how stormwater systems work, why they matter for reducing flooding and pollution, and how everyone plays a role in protecting water resources.
A
Above-ground planter – A large box of topsoil with timber or other sides. A raised bed provides accessibility to plants and is beneficial if there is limited space to grow vegetation.
Aquifer – A layer of sand, gravel, or clay below the earth’s surface that holds enough water for people to withdraw through wells and springs. Rainwater soaks into the ground and replenishes aquifers.
B
Backwater – Water upstream from an obstruction that is deeper than it would normally be without the obstruction.
Baffle – A device used to deflect, regulate, or check the flow of water.
Berm – A constructed barrier of compacted earth.
Best Management Practices (BMPs) – Multiple treatment methods, activities, facilities, and structures that, when used together, help protect water quality by preventing or reducing pollution of stormwater and removing pollutants from runoff before it is discharged to ground or surface water. To learn more: Manual of Best Management Practices
Bio retention cells, swales, planters – Shallow, engineered landscape depressions that receive stormwater runoff, with soil media and plants designed for specific pollutant removal; may or may not have underdrains.
Biofiltration swale – A broad, open, vegetated channel that filters flowing stormwater. The most common form is a wide, shallow, inclined depression planted with grasses.
Brackish water – Water that has more salt than freshwater but less than seawater. In Kansas, brackish water may occur where salt layers in bedrock or saltwater-bearing sandstone are connected to overlying freshwater aquifers.
Buffer – A designated area adjacent to steep slopes, landslide areas, streams, or wetlands that protects slope stability, reduces surface water flow, and minimizes erosion.
C
Catch basins (also called drain inlets) – Underground concrete structures that collect stormwater runoff from the surface—typically through a grated inlet in the gutter or an opening in the curb—and route it into underground pipes. They are designed with a sump or depression below the pipe inlet to allow sediment and debris to settle, and may include inserts or fittings to trap oils and floatables. Catch basins can serve as junctions in a pipe system and may have grated or solid lids. Maintenance often requires specialized expertise and equipment.
Channels or ditches – Constructed waterways that convey stormwater. In Leavenworth, KS, the largest channels include the Missouri River drainage on the east side of town and 3 Mile Creek and 5 Mile Creek on the west side. Many other channels in the main part of town are irrigation ditches supplying water to orchards and gardens, which typically carry very little stormwater.
Cistern or rain barrels – Tanks or barrels used to collect and store rainwater from roofs and gutters.
Clean Water Act (CWA) – The federal environmental law that regulates water quality, including the management of stormwater. To learn more: Summery of the Clean Water Act
Closed detention system – An underground structure, typically a concrete vault or large-diameter pipes, that temporarily stores stormwater and releases it slowly. These systems are used when space for above-ground detention is limited and are accessed via manholes.
Covenants, Conditions, and Restrictions (CC&Rs) – Non-governmental rules for condominiums or homeowners associations. They may include requirements for lawn maintenance and care of stormwater management facilities.
Critical areas – Locations where flooding or erosion conditions present a significant risk to public safety or property.
Culvert – A pipe or concrete box structure that drains water under roadways or embankments, typically without catch basins or manholes along its length.
Curb inlet or storm drain – A catch basin along a curb that collects and conveys stormwater runoff through a slotted cover or curb opening.
D
Drainage swales – Vegetated, sloped depressions that allow water to flow while encouraging infiltration into the ground.
Detention basins – Depressed areas designed to temporarily store stormwater and release it at a controlled rate, reducing downstream pipe sizes and costs.
Detention facility – A pond, vault, or pipe system that temporarily stores stormwater runoff and slowly releases it through a designed outlet, draining completely within hours or days.
Detention pond – An open basin, either excavated or built with embankments, designed to temporarily store stormwater runoff and release it slowly.
Discharge point – The location where a stormwater system empties into a stream, river, lake, or other waterbody.
Ditch – A constructed channel with a top width less than 10 feet at design flow.
Diversion structures – Structures that control the direction or volume of water flow, often using head gates.
Downspout – Part of a roof gutter system that directs water away from a building, ideally onto planted areas to reduce runoff.
Drainage facility – A constructed feature designed to collect, convey, store, or treat surface and stormwater runoff, including streams, pipelines, channels, ditches, gutters, lakes, wetlands, closed depressions, flow-control or water-quality treatment structures, erosion and sediment control measures, and related appurtenances.
Drinking water – Water treated to be safe for human consumption. Conserving drinking water helps municipalities save money. For more information: Leavenworth Waterworks.
Drywell – An underground structure that allows stormwater to infiltrate the ground. Maintenance often requires specialized expertise.
E
Ecosystem – A community of living organisms (plants, animals, microorganisms) and nonliving components (water, air, soil) interacting to create habitats. Polluted water can impair ecosystems.
Environmental Impact Statement (EIS) – A document assessing potential adverse impacts of a project, ways to mitigate them, and alternatives. Required under federal and state environmental policy acts for projects with significant environmental impact potential.
Embankment – A structure of earth, gravel, or similar material raised to form a pond bank or road foundation.
Erosion – The process of moving soil or other materials due to wind, water, ice, or other forces. Runoff increases erosion.
Estuary – A partially enclosed coastal body of brackish water with inflow from rivers or streams and connection to the sea. Estuaries are highly productive habitats.
Eutrophic – A waterbody condition where excess nutrients, particularly phosphorus, stimulate aquatic plant growth and reduce dissolved oxygen for other aquatic life.
F
Filtration – Passing a fluid through a medium to separate solids, such as water passing through soil or plant roots.
Filter strip – A grassy strip along parking lots or roads that removes sediment and pollutants from stormwater before it infiltrates the ground.
Filter vaults or stormwater filters – Underground structures containing filter cartridges to remove sediment and pollutants from stormwater before discharge.
Flow control structure/flow restrictor – A device that restricts or slowly releases stormwater to reduce flooding, erosion, and pollutants.
Freshwater – Water that is not salty; about 3% of Earth’s water is freshwater.
G
Green roofs – Engineered roofs with vegetation that filter water before discharge. Leavenworth currently has few green roofs but may see more in the future.
Groundwater – Water stored underground in soil, sand, or rock, often in aquifers, originating from infiltration. Much drinking and irrigation water comes from groundwater.
H
Habitat – The specific area or environment in which a particular type of plant or animal lives and grows.
Headwaters – The source or origin of a stream.
Hydrologic cycle – The continuous movement of water from the atmosphere to the earth and back, including precipitation, interception, runoff, infiltration, percolation, storage, evaporation, and transpiration.
I
Impervious – A surface that does not allow water to pass through.
Infiltration basin – An open basin, either excavated or constructed with berms or embankments, that temporarily stores stormwater and disposes of it by allowing it to soak into the ground.
Impervious surface – Any surface that water cannot soak into, such as streets, sidewalks, driveways, rooftops, and compacted soils. Urban areas in Leavenworth have many impervious surfaces, which increase stormwater runoff.
Infiltration – The process of water moving into the soil from the surface. Many new stormwater management practices focus on infiltration (green infrastructure).
Infiltration facility – A drainage facility designed to use infiltration/percolation to dispose of surface and stormwater runoff. Examples include infiltration basins, ponds, and underground tanks.
Illicit discharge – Any discharge to the municipal separate storm sewer system (MS4) that is not entirely composed of stormwater, with limited exceptions.
Illicit Discharge Detection and Elimination (IDDE) – A program designed to identify, eliminate, and prevent illicit discharges through inspection, monitoring, and public awareness.
Isopluvial – A line on a map connecting points that receive the same amount of precipitation.
L
Lawn alternative – Low-growing ornamental perennials, ground covers, or native meadow grasses used instead of traditional lawns.
Low Impact Development (LID) – Techniques and designs that manage rainwater on-site by allowing some to evaporate, infiltrate, be captured for reuse, or slowly pass into the stormwater system, reducing runoff and pollution.
M
Maintenance Access Point (Manhole) – Underground structures, typically concrete or corrugated metal, providing maintenance access to storm drainage pipes. Located in paved areas, they are placed at regular intervals or where pipes connect, and some include pre-treatment devices.
Mulch – A layer of organic material applied to soil to enrich it, retain moisture, and prevent erosion.
Municipal Separate Storm Sewer System (MS4) – A storm system with its own set of pipes separate from the sanitary sewer system.
N
Native plantings and trees – Using native vegetation reduces impervious surfaces, increases infiltration, intercepts rainfall, provides wildlife habitat, and improves aesthetics.
Natural conveyance system elements – Swales, small drainage courses, streams, rivers, lakes, and wetlands that naturally convey stormwater.
Natural onsite drainage feature – A natural swale, channel, stream, wetland, closed depression, or lake that conveys or stores stormwater.
Non-point source (NPS) pollution – Pollution from diffuse sources, caused by rainfall or snowmelt moving over and through the ground.
Nonstructural BMP – A preventative action to protect water quality without construction, relying on behavior changes, education, recycling, maintenance, and source controls.
Notice of Intent (NOI) - A formal application submitted to the Kansas Department of Health and Environment (KDHE) to obtain coverage under a stormwater permit, such as the National Pollutant Discharge Elimination System (NPDES) construction stormwater permit. The NOI notifies the state of activities (like construction projects) that may discharge stormwater and outlines how the site will comply with permit requirements to reduce pollution.
National Pollutant Discharge Elimination System (NPDES) – A program created under the federal Clean Water Act that regulates the discharge of pollutants into U.S. waters. In Kansas, the NPDES program is administered by the KDHE. It requires permits for certain activities, such as stormwater runoff from construction sites, municipal storm sewer systems (MS4s), and industrial facilities, to ensure that discharges do not harm water quality.
O
Oil-water separator – An underground vault that mechanically separates oil from stormwater, typically used where high oil concentrations are expected (parking lots, fueling stations).
On-site Sewage/Septic System (OSS) – Multi-stage systems that collect, treat, and disperse wastewater to soils rather than a centralized treatment plant.
Outfalls – Points where stormwater discharges from a system into a stream, river, or lake. In Leavenworth, outfalls provide locations for water quality monitoring and indicate responsibility transitions between agencies.
P
Permeable pavers – Modular paving systems with gaps filled with permeable material to allow water infiltration.
Permeable surface – Paving that allows water to pass through and infiltrate the ground.
Pervious concrete – Rigid pavement with large spaces to allow water infiltration, used for driveways and parking lots.
Pipes – Leavenworth’s stormwater system includes nearly 50 miles of underground pipes, ranging from 12″ to 96″ in diameter, made of concrete, corrugated metal, or HDPE.
Pre-treatment inlets or oil/water separators – Drain inlets designed to remove common pollutants. Sediment settles, oils and floatables remain at the top, and water is discharged to the stormwater system.
Porous asphalt – Flexible pavement with large spaces for water infiltration, bound with bituminous material.
Point discharge – Release of concentrated stormwater runoff from a pipe, culvert, or channel.
Point source pollution – Pollution traced to a specific source, such as a factory, spill, or wastewater treatment plant.
R
Rain barrel – A container that collects and stores roof runoff, typically 30–100 gallons, made of wood or plastic.
Rain garden – A specially designed, site-specific depression planted with vegetation that captures runoff from parking lots, roads, driveways, or rooftops, filtering pollutants and allowing infiltration. If you want to learn more: Rain Garden Guide
Rainwater harvesting – The collection of rainwater in planted areas (rain gardens, green roofs) or containers (rain barrels, cisterns) to reduce runoff. Harvested water is usually used for non-potable purposes like irrigation or grey-water flushing.
Receiving waters – Bodies of water that receive stormwater from upstream natural or man-made systems.
Retention – The collection and holding of stormwater with no surface outflow.
Retention facility – A drywell, vault, infiltration basin, or pond that holds stormwater while it soaks into the ground.
Riparian – Pertaining to the banks of rivers, streams, wetlands, or lakes.
Riprap – A protective layer of stones placed to prevent erosion of embankments or structures.
Runoff – Water from precipitation that flows over surfaces into drainage systems, streams, rivers, lakes, wetlands, or shallow groundwater.
S
Sediment – Primarily eroded soil, but also dirt from rooftops or paved surfaces. Sediment is often carried into water bodies with stormwater runoff.
Sewer system – Pipes and pump stations that collect and transport wastewater from homes and businesses to a treatment plant. Wastewater comes from sinks, showers, toilets, and washing machines. In Leavenworth, stormwater is generally not treated before discharge.
Site planning and design – A multidisciplinary approach to locating buildings, roads, and other features to minimize impervious surfaces and impacts on critical habitats and waterways.
Soil amendments – Products like gypsum or lime added to soil to improve physical qualities and nutrient availability for plants.
Source control – Identifying and preventing potential pollution before it reaches water bodies, including inspections, cleanup, stormwater management, coordination among agencies, and public education.
Storm drain or curb inlet – A type of catch basin that collects and conveys stormwater runoff.
Stormwater – Water from rainfall or snow that flows off surfaces like rooftops, streets, highways, lawns, or gravel lots into drainage systems, streams, rivers, or lakes.
Stormwater treatment facility – A landscaped feature or structure that captures, conveys, slows, detains, or treats stormwater, including detention and retention facilities.
Storm and Surface Water Management Program – A plan outlining stormwater programs and capital projects, addressing regulatory requirements, emerging technologies, flooding and water quality issues, and resources. To learn more: Stormwater Management Program
Storm drain system – Gutters, pipes, streams, or ditches that carry surface and stormwater to nearby water bodies.
Stormwater engineer – A professional who designs solutions for stormwater runoff and pollution issues.
Stormwater facility – A facility that controls stormwater discharge, including storage (ponds, vaults, underground tanks), water quality (wet ponds, bioswales, constructed wetlands, sand filters, oil/water separators), and conveyance systems (ditches, pipes, catch basins).
Stormwater Pollution Prevention Plan (SWPPP) – A plan required under the Clean Water Act NPDES program that outlines strategies to reduce polluted stormwater runoff, improve water quality, identify priority watersheds, and describe stormwater management actions to prevent pollution and ensure regulatory compliance.
Stormwater pollution – Anything in stormwater that makes it unclean, including soil, pesticides, litter, oil, grass clippings, leaves, and bacteria.
Stormwater runoff – Water from rainstorms, irrigation, or other sources that flows across streets, parking areas, rooftops, lawns, and other impervious surfaces instead of soaking into the ground. This runoff carries pollutants to nearby creeks, rivers, and lakes, and moves faster over impervious surfaces, increasing erosion and pollutant transport.
Stormwater system – A network of catch basins, pipes, and/or facilities for conveying, detaining, or treating stormwater. Not to be confused with sanitary sewers.
Structural BMP – Constructed facilities or measures designed to protect water quality and control stormwater quantity. Examples include storage, vegetation, infiltration, and filtration structures.
Sumps – Concrete or metal cylinders, 5–10 ft deep, with side perforations designed to allow water to drain into subsurface soils.
Surface water – Water found above land, including oceans, lakes, rivers, streams, ponds, and wetlands.
Surface Water Design Manual – The formally adopted manual describing surface and stormwater design and analysis requirements, procedures, and guidance.
T
Total Maximum Daily Load (TMDL) – The maximum amount of a pollutant a water body can receive while meeting water quality standards. Standards define uses such as drinking water, recreation, or aquatic life support.
Total Suspended Solids (TSS) – A measure of the solid particles, such as soil, silt, organic matter, or debris, that are suspended in water and can be trapped by a filter. High TSS levels can make water cloudy (turbid), reduce light penetration, smother aquatic habitats, and carry pollutants like nutrients, bacteria, or metals. In stormwater management, reducing TSS is important to protect water quality in creeks, rivers, and lakes.
Toxic – Poisonous or harmful to life, including carcinogenic substances.
Treatment train – Two or more stormwater treatment facilities connected in series to improve water quality.
Treatment wetland – A shallow man-made pond designed to treat stormwater biologically through dense wetland vegetation and sediment settling.
U
Underdrain – Perforated pipes installed at the bottom of stormwater features to collect and remove excess runoff.
V
Vegetated swale – A landscaped drainage course with gently sloped sides, vegetation, compost, and/or rock, designed to remove silt and pollutants from surface runoff.
Vegetated roofs – Engineered systems with a thin layer of soil and plants to capture rain on roofs.
W
Wastewater treatment (sewage) plant – Municipal facilities that treat wastewater from homes and businesses before discharging it into a stream or river. In Leavenworth, stormwater is generally not treated at these facilities. To learn more: City of Leavenworth Water Pollution Control
Water cycle – The continuous movement of water above, on, and below the Earth in liquid, gas, and solid phases. Water on Earth today is the same as when the planet formed.
Watershed – The entire land area from which water drains to a common outlet, such as a stream, river, lake, or other water body. In Leavenworth, KS, all residents live within a watershed and are upstream or downstream from other watersheds. Watersheds are often named after their outlet, e.g., the Missouri River Watershed, and the term is sometimes used interchangeably with drainage basin or catchment.
Wet season – In Leavenworth, KS, the wet season generally occurs in spring and early summer, from April through June, when rainfall is highest, often from thunderstorms. Secondary peaks can occur in late summer or early fall.
Wetland – An area inundated or saturated by surface or groundwater often enough to support vegetation adapted to saturated soils, including swamps, marshes, bogs, and similar areas.
Wetpond/Wetvault – Stormwater treatment facilities that contain a permanent pool of water. Designed to optimize water quality by providing long retention times for sediment settling and biologic activity. Wetvaults have a covered pool to limit sunlight-dependent biological activity.
X
Xeriscaping and water-efficient plants – Landscaping and gardening methods that reduce or eliminate the need for irrigation, using drought-tolerant and low-water-use plants.
Common Stormwater types of pipes and their abbreviations:
Reinforced Concrete Pipe (RCP)
High-Density Polyethylene (HDPE)
Polyvinyl Chloride (PVC)
Corrugated Metal Pipe (CMP)
Ductile Iron Pipe (DIP)
