Water Treatment

Glossary of Water Quality Terms

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

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.

Fecal coliforms: a group of organisms found in the intestinal tracts of people and animals. Their presence in water usually indicates pollution that may pose a health risk.

Ground water: the supply of fresh water that is found under the earth¹s surface in underground rock formations or soil.

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

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

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.

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).