Watershed Glossary

Best Management Practices (BMPs)

Structural, nonstructural, and managerial techniques that are recognized to be the most effective and practical means to control nonpoint source pollutants yet are compatible with the productive use of the resource to which they are applied.


Storage of water over brief periods of time to manage the flow.

E. coli

E. coli, Escherichia coli, is a common type of bacteria that lives inside of the intestines of warm blooded animals. In the environment, it comes from human and animal waste.

Fecal Coliform Bacteria

Fecal coliforms are bacteria that are associated with human or animal waste. Their presence is a strong indication of sewage or animal waste contamination, however, not all fecal coliforms originate from feces.

Ground Water

The supply of fresh water found beneath the Earth`s surface, usually in aquifers, which is often used for supplying wells and springs.


Used in reference to surfaces that are resistant to the movement or passage of water. Impervious surfaces can include asphalt, concrete, rooftops, and highly compacted soils.


The flow of water from the land surface into the soil or subsurface.

Non-Point Source

Pollution sources which are diffuse and do not have a single point of origin, or are not introduced into a receiving stream from a specific outlet. The pollutants are generally carried off the land by stormwater runoff. The commonly used categories for non-point sources are: agriculture, forestry, urban, mining, construction, dams and channels, land disposal, and saltwater intrusion.


Any substance that is assimilated (taken in) by organisms and promotes growth. Nitrogen and phosphorous are nutrients which promote the growth of algae.

Nutrient pollution

Contamination of water resources by excessive inputs of nutrients; in surface waters, excess algal production is a major concern.

Point Source

A stationery location or fixed facility from which pollutants are discharged or emitted. Also, any single identifiable source of pollution, e.g., a pipe, ditch, ship, ore pit, or factory smokestack.


Generally, any substance introduced into the environment that adversely affects the usefulness of a resource.


Stormwater runoff, snow melt runoff, and surface runoff/drainage that flows over the ground surface or through the ground directly into streams, rivers, or lakes.

Surface Water

All water naturally open to the atmosphere (rivers, lakes, reservoirs, streams, etc.).

Total Maximum Daily Load (TMDL)

A TMDL is a calculation of the maximum amount of a pollutant that a water body can receive and still meet water quality standards.


The land area from which water drains into a stream, river, or reservoir. An area of land that contributes runoff to one specific delivery point; large watersheds may be composed of several smaller “subwatersheds,” each of which contributes runoff to different locations that ultimately combine at a common delivery point.