GLOSSARY
This glossary provides non-technical definitions of technical terms that are used in this report.
| algal blooms | An algae population explosion that can turn clear water to a cloudy green color. In extreme cases, thick, foul smelling scum forms on the water and fish kills may occur when decomposing algae depletes the water’s oxygen supply. |
| duff layer | The accumulation of decaying leaves, pine needles, and other plant material that falls to the ground. |
| estuary | Partially enclosed bodies of water where saltwater from the ocean mixes with freshwater from rivers and streams. |
| fecal coliform bacteria | Bacteria found in fecal wastes originating from the digestive systems of warm-blooded animals. The measurement unit for fecal coliforms is counts (i.e., number of colonies counted under a microscope) per 100 milliliters of water sample. |
| geometric mean | Type of averaging that tends to damp out the bias that extremely high or extremely low test results normally have on an average. |
| impervious surfaces | Relatively waterproof surfaces such as pavement that shed rainfall and snowmelt rather than letting it seep into the ground. |
| polluted runoff | Rainfall and snowmelt that washes over a developed landscape and picks up pollutants that have dripped, dropped, or been deposited onto the ground. Nonpoint source pollution is another term for polluted runoff. |
| sediment forebay | Small basin built to capture coarse sediment from stormwater runoff before it is discharged into a stormwater control structure. |
| storm sewer | Underground pipes that drain rainfall and snowmelt that collects in developed, typically paved, areas into water bodies. |
| stormwater | Rainfall and snowmelt that washes over the landscape. Stormwater that washes over developed land meets the same definition as polluted runoff. |
| subwatershed | The land area that drains rainfall and snowmelt into a tributary contained within the larger watershed. |
| vegetated buffer | A strip of land along a water body that is composed of trees, shrubs, groundcovers, and a "duff" layer. A mature vegetated buffer both slows and filters runoff before it enters a water body. |
| water body | A natural or manmade feature in the landscape that holds flowing or standing water. |
| watershed | All of the land that slopes down to a water body, such as the Libby River, so that rainfall and snowmelt flowing over the land eventually reaches the water body. |
| watershed survey | A search, or survey, of a watershed for sources of polluted runoff. |
| 90th percentile value | A statistical term for the value in a group of numbers where 90 percent of the numbers are equal to or below the value. |