Fact Sheet

What's It Mean?

Heard some terms that were unfamiliar? Below is a glossary of terms associated with water quality and the environment. For more information and application of these terms, see our Water Quality Web site.

Acid rain: rain having a pH lower than 5.2-5.6; typically caused by sulfur and nitrogen acids created by human involvement.

Algae: Simple one-celled, colonial, or multi-celled aquatic plants.

Algal bloom: algae that can be a hazard to humans and aquatic life.

Cyanobacteria: Blue-green algae, or "pond scum," as it is often called, do not harm aquatic life directly. However, as they die and decay in large numbers, bacteria that consume them may deplete the oxygen in the water.

Decompose: the process of bacteria breaking down organic matter into smaller pieces.

Detritus: dead or decaying organic matter, often called organic detritus.

Dissolved oxygen: concentration of free oxygen molecules dissolved in water, usually measured in milligrams per liter, parts per million, or percent of saturation.

Ecosystem: the relationship between living organisms and their non-living surroundings, where both living and non-living mutually depend on each other.

Estuary: a large river of water that mixes the freshwater of the river with saltwater from the approaching ocean.

Eutrophication: process by which bodies of water are enriched by nutrients (usually phosphorus and nitrogen) which leads to excessive plant growth.

Fish kill: a sudden and massive fish death caused by insufficient oxygen.

Nonpoint source pollution: Nonregulated pollution, typically from various sources such as pesticides, car exhaust, fertilizer, and even sediment. Everyone contributes nonpoint source pollution.

NPDES permit: a permit that industries contributing point source pollution must obtain before they can legally operate. They must also maintain the permit on a timely basis.

Nutrient loading: when too many nutrients are added to a water system through nonpoint source pollution. For a full explanation of how nutrient loading endangers aquatic life, see the Water Quality Web site.

Organic: substances containing carbon atoms and carbon-carbon bonds.

Pfiesteria: Short for Pfiesteria Piscicida, this dinoflagellate (a single-celled alga) is typically found in coastal waters from Delaware and North Carolina and has 24 reported forms, a few of which produce toxins.

Point source pollution: emanates from one specific place, or point. The most common origins of this type of pollution are pipes from industrial plants or factories, storm sewers on city roads and large feedlots or animal waste lagoons with a specific area of discharge. Point source pollution requires an NPDES permit.

Pollution: any substance that exists in the environment that is undesirable or harmful for that environment.

River basin: a watershed that drains directly into a river.

Sediment: soil that washes into a body of water or wetland and contributes additional nutrients to a body of water. Sediment ncludes decaying algae and weeds, and soil and organic matter eroded from the watershed.

Turbidity: Degree to which light is blocked because water is muddy or cloudy.

Watershed: the area in which water, sediments, and dissolved minerals drain from higher elevations to a larger body of water, such as a stream, river, lake, estuary or ocean. See the Water Quality Web site for a demonstration of what a watershed does and what happens when it cannot function properly.

Wetlands: any area where water covers the soil for at least part of the year, including marshes, swamps, bogs and other marshy areas.