Glossary of Terms

Beach

The sandy, pebbly, or rocky part of the shore of a body of water washed by the tide or waves.

Bioretention

The process in which contaminants and sediment are removed from runoff by collecting it into a ponding area consisting of a grass buffer strip, sand bed, organic layer, soil, and plants.

Bioretention Basins

Landscaped slopes or shallow basins used to slow and treat runoff onsite.

Biotreatment

The treatment of waste materials to remove pollutants or toxic substances through a biological process, such as using bacteria to remove contaminants.

BMPs (Best Management Practice)

Best management practice or device that helps to control, treat, or prevent runoff pollution.

Boom

Containment structure placed in waterways that controls the spread of pollutants to a single area.

Catch Basin

An inlet to a storm drain that includes some type of screening material, such as a grate, that helps to remove sediment and debris from entering storm drains.

Channels

Man-made basin which lets water flow and eventually drain into a river or other body of water.

Drainage Area

The land area where precipitation falls off into creeks, streams, rivers, lakes, and reservoirs.

Erosion

The process in which soil and rock are worn away or removed from a surface by the action of waterflow, wind, or physical means.

Estuaries

A coastal wetland created when salt water from the ocean mixes with nutrient-rich fresh water from inland sources.

Eutrophication

Excessive richness of nutrients in a lake or other body of water, frequently due to runoff from the land, which causes a dense growth of plant life and death of animal life from lack of oxygen.

Evapotranspiration

The process by which water is transferred from land to the atmosphere by evaporation from soil and evaporation of water from plant leaves (transpiration).

Green Roofs

A vegetative layer grown on a rooftop.

Green Waste

Biodegradable waste, such as branches, twigs, flowers, leaves, and grass clippings. Green waste includes all items that can be composted.

Groundwater

Groundwater is fresh water that soaks into the soil and is stored in the tiny spaces between rocks and particles of soil.

HHW (Household Hazardous Waste)

Household products that are flammable, corrosive, toxic, or can explode under certain circumstances.

Hydrologic

Relating to the science of water movement, distribution, quality, cycles, resources, and watersheds. Hydrologic character refers to the components that impact how water behaves in a certain area.

Illegal Discharge

Anything entering the storm drain system that is not rainwater, unless exempted by local ordinance.

Impermeable Surface

Impermeable surfaces are solid surfaces that don’t allow water to penetrate, forcing it to run off. Common impermeable surfaces include asphalt; concrete; and grouted stone, brick or concrete pavers.

Infiltration

The process of water entering the soil through rainfall and irrigation events.

IPM (Integrated Pest Management)

Long-term prevention of pests through a combination of techniques such as biological control, habitat manipulation, modification of cultural practices, and use of resistant varieties.

Irrigation Tune-Up

A test of a yard’s irrigation system to ensure water isn’t running off the property due to system leaks, misaligned or broken sprinklers, or unnecessary overwatering. Irrigation tune-ups are recommended to be conducted seasonally or every three months.

LID (Low Impact Development)

Refers to systems and practices that use or mimic natural processes that result in the infiltration, evapotranspiration, or use of stormwater to protect water quality and associated aquatic habitat. LID is an approach to land development (or re-development) that works with nature to manage stormwater as close to its source as possible.

MS4

Municipal Separate Storm Sewer System. A municipal conveyance system that collects and carries runoff that is not combined with the sewer system.

Mulch

Any material used as a covering to protect soil and surrounding plants, prevent weed growth, retain moisture, and reduce runoff pollution.

NPDES

National Pollutant Discharge Elimination System. The part of the Clean Water Act which requires point source discharges to obtain permits. NPDES permits are administered by the California Department of Natural Resources.

Ocean

A large body of salt water.

Permeable Surfaces

Surfaces which allow water to penetrate through and into the soil. Permeable surfaces filter out pollutants and recharge ground water sources.

Precipitation

Water released from clouds in the form of rain, hail, freezing rain, sleet, or snow.

Rain Garden

An area with adapted or deep-rooted native plants and grasses that collects rainwater runoff to infiltrate into the ground.

Rainwater Bump Outs

Plant-filled curb extension that protrudes into the street at mid-block or at an intersection to collect, infiltrate, and absorb runoff.

River

A large natural stream of water flowing in a channel to the sea, a lake, or another such stream.

Runoff

The flow of water over land that does not infiltrate into the ground.

Sanitary Sewers

Sanitary sewers carry raw sewage from homes and businesses to wastewater-treatment facilities.

Sewer Laterals

Sewer laterals are the pipes that carry wastewater from indoor plumbing fixtures like toilets‚ sinks‚ and dishwashers to the public sewer line under the street.

Source Control Measures

Elimination of pollutant sources through either product substitution or green chemistry.

Storm Drain

A structure that collects excess runoff from paved streets, parking lots, sidewalks, and roofs.

Stormwater

Water from rain events that runs off roofs, driveways, parking lots, yards, and other surfaces that does not absorb into the ground.

Stormwater Infiltration System

System which collect rainwater to help it infiltrate into the groundwater basin.

Structural Best Management Practices

Structural best management practices are facilities that help to prevent pollutants in runoff from leaving a developed property, entering our storm drains, and impacting our local waterways. Examples include detention basins and vegetated strips next to pavement.

total maximum daily loads

The maximum amount of a pollutant a waterway can contain while still meeting the state’s water quality standards.

Tree Box Filters

Mini bioretention areas installed beneath trees which helps to control stormwater runoff and filter out contaminants.

U.S. EPA

United States Environmental Protection Agency. A federal government agency that writes and enforces regulations based on laws passed by Congress to protect human health and the environment.

Water Quality Improvement Plan

Water Quality Improvement Plans include descriptions of the highest priority pollutants or conditions in a specific watershed, goals and strategies to address those pollutants or conditions, and time schedules associated with those goals and strategies.

Watershed

The land area that channels rainfall to creeks, streams, rivers, and eventually to reservoirs, bays, and the ocean. No matter where you live…you live in a watershed.

Watershed Divide

Elevated land (such as ridges, hills, or mountains) that forms a boundary to separate different watersheds, river systems, or drainage basins.

Wetland

Land or areas (such as marshes or swamps) that are covered, often intermittently, with shallow water or have soil saturated with moisture.