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Water: Educator Resources

Technically Speaking - Glossary of Terms

Algal bloom: a sudden, excessive growth of algae in a waterbody.

Clarity: a measure of the amount of particles suspended in water; determined by using a secchi disk or turbidity test.

Combined sewers: Pipes that carry both storm water and household sewage to sewage treatment plants. During a big storm, they may overflow and dump untreated sewage into streams, lakes and coastal waters. These overflows are called combined sewer overflows or CSOs.

Designated use: the desired use a waterbody should support (like fishing or swimming).

Dissolved oxygen (DO): the amount of oxygen dissolved in water. The amount is usually expressed in parts per million (ppm) or milligrams per liter (mg/L).

Estuary: the area where the fresh water of a river meets and mixes with the salt water of the ocean.

Ground water: the supply of fresh water that is found under the earth's surface in underground rock formations or soil.

Impervious surface: A paved or other hard surface that does not allow water to penetrate.

Livestock operation: a facility that raises animals such as cows, sheep, or hogs. Fecal coliform bacteria are present in livestock waste.

Macroinvertebrate: organism that lacks a backbone and is large enough to be seen with the naked eye.

Meandering stream: one that follows its natural course creating winding curves.

National Water Quality Inventory: a report EPA prepares every 2 years summarizing information from states about the quality of the nation's waters.

Nitrogen: a nutrient that is essential to plants and animals.

Nutrients: substances necessary for the growth of all living things, such as nitrogen, carbon, potassium, and phosphorus. Too many nutrients in waterbodies can contribute to algal blooms.

Particulates: small pieces of material (such as sand) floating in the water.

Pervious surface: A surface which allows water to soak into it.

pH: a symbol for expressing the degree to which a solution is acidic or basic. It is based on a scale from 0 (very acid) to 14 (very basic). Pure water has a pH of 7.

Phosphorus: a nutrient that is essential to plants and animals.

Photosynthesis: The conversion of light energy to chemical energy. At night, this process reverses: plants and algae suck oxygen out of the water.

Runoff: water from rain, snowmelt, or irrigation that flows over the ground and returns to streams. It can collect pollutants from air or land and carry them to streams and other waterbodies.

Secchi disk: a black-and-white disk used to measure the clarity of water. The disk is lowered into the water until it cannot be seen and then the depth of the disk is measured. Septic system: a system that treats and disposes of household wastewater under the ground.

Turbidity: a measure of the degree of clarity of a solution. For cloudy water, turbidity would be high; for clear water, turbidity would be low.

Watershed: the area of land that drains into a specific waterbody.

Wetland: an area where water covers the soil or is present either at or near the surface of the soil all year (or at least for periods of time during the year).


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