Agricultural storm water runoff: storm water runoff from orchards, cultivated crops, pastures, ranch lands, and other nonpoint source agricultural activities.

Algae: a group of microscopic, photosynthetic, rootless plants that grow chiefly in water.

Animal waste: animal manure, litter or bedding; water that has contacted animal manure, litter, or bedding; water from washing, flushing, or cleaning animal pens; and liquid or solid waste from pens used at kennels, animal hospitals, poultry processing facilities, dairies or rendering plants.

Antifreeze: a toxic chemical liquid that is added to a vehicle's radiator to protect the engine from freezing during cold weather and overheating during hot weather. Antifreeze is commonly ethylene glycol, and can be major source of storm water pollution if not disposed of properly.

Bacteria: single-cell microscopic organisms that break down organic materials. Some can cause disease in plants or animals.

Bioassessment: the study of the biological community (aquatic insects, fish, plant life) of a body of water to help assess the health of the water. See also macro invertebrates, pollution-tolerant organisms, and pollution-sensitive organisms.

Biodegradable: capable of being decomposed by natural biological processes.

Composting: mixing together leaves, grass clippings, table scraps, and soil and allowing the mixture to decompose into mulch that is high in nutrients and useful to fertilize gardens and flower beds.

Contamination: the introduction of a substance to a water supply that makes the water bad for humans and other organisms in nature.

Decomposition: the breakdown or decay of organic materials.

Detergent: a cleansing agent made from chemical compounds.

Discharge: any addition, introduction, release, or flow of any pollutant, storm water or other substance, whether separate or mixed, into the storm drainage system, waters of the United States, or state water body. The term includes any spilling, leaking, pumping, pouring, emitting, emptying, escaping, leaching, dumping, disposing, or other type of release or discharge engaged in, caused, or permitted by the discharger.

Dredging: removing solid matter from the bottom of a water body to make a deeper channel.

Ecosystem: the biological community (living organisms) and the non-living environment functioning as one system.

Endangered species: plants or animals in serious danger of becoming extinct.

Erosion: the wearing away of the earth's surface by running water, wind, ice or other agents; processes, including weathering, dissolution, abrasion, corrosion, and transportation, but which material is removed from the earth's surface.

Extinct: no longer living.

Fertilizer: a substance used to increase growth of a plant or improve the quality of a crop. When used inappropriately, can contribute to storm water pollution.

Floatable debris: trash floating in the water, such as tires, discarded cans and bottles and other garbage.

Hazardous waste: any discarded solid, liquid, or gaseous material that can harm humans or other animals.

Hydrologic cycle(water cycle): the movement of water from the atmosphere to the earth and back to the atmosphere through precipitation (rain, sleet and snow), runoff, and evaporation.

Landfill: a large, outdoor area for waste disposal.

Macroinvertebrate: an animal without a backbone large enough to be seen without a microscope.

Microorganism: a living thing that is visible only through a microscope.

Motor vehicle fluid: any vehicle oil, antifreeze, transmission fluid, brake fluid, lubricant, gasoline, diesel fuel, or other fluid used in a motor vehicle.

Mulch: any material such as straw, sawdust, leaves, plastic film, or pine bark that is spread upon the surface of the soil to protect the soil and plant roots from the effects of raindrops, soil crusting, freezing, and evaporation.

Nonpoint source pollution: pollution that cannot be traced to a specific point because it comes from many individual places or a widespread area (such as agricultural sites).

Nutrient: an element or compound, such as nitrogen, phosphorous, and potassium that is necessary for plant growth.

Nutrient pollution: human-caused addition of excess nutrients, such as grass clippings and abandoned pet waste, that is delivered to creeks, lakes and rivers through storm water runoff.

Oil: any kind of oil in any form, including petroleum, fuel oil, motor oil and crude oil.

Organic materials: carbon-containing substances found in plants, animals, and their remains.

Organism: a living thing, including humans, plants and animals.

Pesticide: any chemical or biological agent that kills plant or animal pests.

Point source pollution: pollution that can be traced to a single point source, such as a pipe or culvert.

Pollutant: any substance that causes pollution.

Pollution prevention: processes, practices or products that reduce or eliminate pollutants.

Pollution-sensitive macroinvertebrates: aquatic organisms that cannot live in polluted water. These include mayflies, caddisflies, dobsonflies, stoneflies, crayfish, alderflies, craneflies, dragonflies, riffle beetles, whirligigs and damselflies.

Pollution-tolerant macroinvertebrates: aquatic organisms that can live in polluted water. These include leeches, midges, aquatic worms, gilled snails, black flies, and lunged snails.

Retaining wall: A wall built to support or prevent the advance of dirt or water.

Runoff: the portion of rainfall, melted snow, or irrigation (such as water from a lawn sprinkler) that flows across the land's surface, does not soak into the ground, and eventually runs into larger water bodies. May pick up and carry a variety of pollutants. In Dallas, runoff enters the storm drain system; the storm drain system empties runoff into creeks, lakes and the Trinity River.

Sanitary or sewer system: an underground system of pipes used to carry wastewater to a treatment plant.

Sediment: material suspended in water that consists of particles of rocks, soil and organic materials. Sediment is a major nonpoint source pollutant that other pollutants may attach to. Construction site erosion is a major source of sediment pollution.

Silt: small particles of rock, soil or organic material suspended in water.

Storm sewer or storm drain: a sewer or pipe that carries surface water runoff, street waste, and snow/ice melt from the land directly into a nearby body of water.

Storm water: the rainfall that flows over yards, streets, alleys, parking lots, farms and buildings and enters the storm drain system.

Storm water drainage system: a system of streets, roads, storm drains, curbs, gutters, ditches, creeks, lakes and rivers that are designed or used exclusively to collect and transport storm water.

Surface runoff: rain water that flows across surfaces rather than soaking into the ground. It eventually enters a creek, river or lake and may pick up and carry a variety of pollutants.

Toxic: harmful, destructive, or deadly to humans, animals and plants.

Wastewater: water that has been used for washing or cleaning and which contains waste products. Discharged into the wastewater system and carried to a wastewater treatment plant.

Wastewater treatment: physical and chemical processes used to remove pollution from wastewater before discharging it into a water body.

Water pollution: any human-caused contamination of water that reduces its usefulness to humans and other organisms in nature.

Watershed: the total land area that contributes runoff to a particular water body.

Yard waste: leaves, grass clippings, yard and garden debris and brush that result from yard care.