Process using living material (plants) to capture and decompose pollutants in stormwater runoff. Plants hold back sediments and take up excess nutrients, such as phosphorus, that are not healthy for our water bodies.


Process using plants and soils to remove pollutants from stormwater runoff.

dissolved metal

Metals dissolved in water such as copper dust from vehicle brake pads, certain metals left in the rain, and others. Dissolved metals are toxic to fish and other aquatic creatures.

fecal bacteria

found in the guts and feces of mammals. When fecal bacteria is detected in lakes, streams, and sea water, that tells us other pathogens (disease-causing germs) may be in the water as well. These pathogens, including giardia, E. coli, parvovirus, toxoplasmosis, and roundworms, can make people or animals sick.


Fertilizer is applied to soils or to plants to help plants grow. Fertilizers can be made of natural or synthetic materials, and include the nutrients nitrogen (N), phosphorus (P), and potassium (K).


Water found underground in the cracks and spaces in soil, sand, and rock.


Chief components of petroleum and natural gas which are toxic to living things.

impervious surface

hard surfaces such as roads, driveways, parking lots, roofs, and even many lawns, which do not allow water to soak in


When rainwater soaks in, filters through, or seeps into the ground to the groundwater below.


The process of capturing runoff and giving it time to soak into the soil.


Human-made features such as buildings, roads, sidewalks, bridges, pipes, and power supplies.

low impact development

Also known as LID, this is set of stormwater design and landscaping practices that can reduce runoff, sediment loading, and pollution by managing runoff as close to its source(s) as possible.

low impact landscaping

landscaping using native plants and natural processes to capture and treat nearby sources of stormwater runoff.

nonpoint source

A source of water pollution coming from multiple places making it difficult to identify and control.

nutrient pollution

A type of pollution caused by nitrogen or phosphorus that stimulates an overgrowth of algae in water.


Substances that have harmful effects to living things. Captured in stormwater as it runs off surfaces, these substances include metals, pesticides, grease, and oil that are harmful even in small concentrations.


rain, melted snow, and overflowing irrigation water that flows off hard surfaces into stormdrains, creeks, lakes, and the sea.

storm drain

A drain that is designed to collect rain, snowmelt, and ground water.

trash rack

Trash rack is a metal structure that maintains water flow and prevents debris from entering stormwater systems.