Definitions

A Brief Decription of Words and Terms

Best Management Practices (BMPs) - Methods and practices such as good housekeeping, spill prevention, or treatment measures that prevent or minimize pollutant discharges to municipal

Erosion - The washing away of soil by moving water. The water may be in many forms: falling raindrops, surface flow over the ground surface, in creeks or other channels, or waves against the shore of a lake or bay.

Habitat - The specific area or environment in which a particular type of plant or animal lives. An organism's habitat must provide all of the basic requirements for life and should be free of harmful contaminants.

Groundwater - Water stored underground that fills the spaces between soil particles or rock fractures. A zone underground with enough water to withdraw and use for drinking water or other purposes is called an aquifer.

Illegal Discharges or Illicit Connections - These discharge non-storm water to municipal storm drain systems and contribute to water pollution.

Impervious Surface - Any surface that cannot be easily penetrated by water. Examples include pavement, buildings, compacted soils, and rock outcrops.

Nonpoint Source Pollution - Pollution that enters water from dispersed and uncontrolled sources, such as rainfall or snowmelt moving over and through the ground rather than single, identifiable sources.

NPDES - National Pollutant Discharge Elimination System, a provision of the Clean Water Act that prohibits discharge of pollutants into waters of the United States unless a special permit is issued by EPA, a state, or another delegated agency.

Perennial Stream - A stream channel that has running water throughout the year. In the Bay Area, stream flow during the dry season is supplied naturally by springs.

Pollutant - An undesirable substance added to the environment. Water pollutants can cause harm because of their chemical properties (as with insecticides and some metals), physical presence (e.g. dirt or sediment), or through biological action (e.g. bacteria or viruses that affect humans). Pollutants in surface water may originate from either point sources or non-point sources.

Riparian Area - Habitat found along the bank of a natural and freshwater waterway, such as a river, stream, or creek, that provides for a high density, diversity, and productivity of plant and animal species.

Runoff - Water from rain, melted snow, or agricultural or landscape irrigation that flows over the land surface.

Storm Drain System - The system built to collect and transport rain to prevent flooding in urban areas. Anything that flows or is discharged into the storm drain system goes directly into local creeks or San Francisco Bay without any treatment.

Sanitary Sewer System - The system that collects and transports sanitary wastes from interior building plumbing systems to the wastewater treatment plant to be treated. In Alameda County, rain water that falls on streets, roofs and other exterior surfaces usually does not pass through this system (see Storm Drain system).

Stormwater Runoff - Rain that flows off the surface of the land without entering the soil.

Structural Control - A facility, such as a stormwater detention basin, designed to mitigate the impact of stormwater runoff by removing pollutatants or attenuating flow.

Urban Runoff - Urban Runoff is rain and any other water that passes through and out of developed areas (streets, parking lots, roof tops, etc.) into adjacent waterways.

Watershed - The geographic region within which water dr