Basin – a large area of lower elevation than the surrounding areas.

Benthic invertebrates – insects, mollusks, crustaceans, worms and other organisms without a backbone that live in, on or near the bottom of lakes, streams and oceans.

Best Management Practices (BMPs) - a method, activity, maintenance procedure, or other management practice for reducing the amount of pollution entering a body of water.

Contour – a line drawn on a map connecting points of equal elevation.

Digital Elevation Model (DEM) – a representation of the topography of the earth in digital format, that is, by coordinates and numerical descriptions of altitude.

Fecal coliform – microscopic, single-celled organisms found in the wastes of warm-blooded animals.

Floodplain – the relatively level area of land bordering a stream channel and inundated during moderate to severe floods.

Geographic Information Systems (GIS) - a computer system for capturing, storing, checking, integrating, manipulating, analyzing and displaying data related to positions on the earth’s surface.

Groundwater – water beneath the surface of the earth which saturates the pores and fractures of sand, gravel, and rock formations.

Growing Greener – the PA Department of Environmental Protection's Growing Greener Program, enacted in 1999, provides the funding necessary to preserve farmland and protect open space; eliminate the maintenance backlog in state parks; clean up abandoned mines and restore watersheds; and provide new and upgraded water and sewer systems across the Commonwealth.

Hydrology – the science of dealing with the properties, distribution, and circulation of water on the surface of the land, in the soil and underlying rocks, and in the atmosphere.

Hydrologic Modeling – the use of physical or mathematical techniques to simulate the hydrologic cycle and its effects on a watershed.

Impervious Surface – a hard surface area that either prevents or retards the entry of water into the soil mantle or causes water to run off the surface in greater quantities or at an increased rate of flow. Common impervious surfaces include, but are not limited to, rooftops, walkways, patios, driveways, parking lots, storage areas, concrete or asphalt paving, and gravel roads.

Infiltration – movement of water, typically downward, into soil or porous rock.

Macrofauna – animals large enough to be seen with the naked eye.

Non-point source (NPS) – a surface water pollution source that is distributed over an area rather than limited to an identifiable point.

Remediation – the process of correcting environmental degradation.

Riparian – describes areas adjacent to rivers and streams with a high density, diversity, and productivity of plant and animal species relative to nearby uplands.

Runoff – part of the precipitation that flows toward the streams on the surface of the ground or within the ground, and is composed of base flow and surface runoff.

Stormwater – runoff from rain, snow melt, surface water, and other drainage.

Sustainable Development – development with the goal of preserving environmental quality, natural resources, and livability for present and future generations.

Total maximum daily loads (TMDLs) – under the Clean Water Act, a TMDL identifies the amount of a particular pollutant a stream can handle without violating water quality standards.

Turbidity – cloudiness in water derived from algae, suspended silt, or other impurities.

Watershed - the specific land area that drains water into a river system or other body of water.

Wetland – land areas that are wet due to a close relationship to a body of water or groundwater, or land areas that are flooded regularly; they support vegetation adapted for life in saturated soil conditions.