Definition of Terms

There is a lot of technical terms on the Rivers and Streams website. This page is designed to help navigate and define these words and phrases. Use the line below to skip to a certain letter.
Material through which water cannot pass or passes with great difficulty.
Natural or artificial body of water that is confined by a structure such as a dam to retain water.
Index of biotic integrity (IBI):
A measure of the degree to which aquatic resource quality deviates from what would be expected at an undisturbed location. Calculated based on data from biological communities that measure species composition, trophic position, species abundance, and condition.
Indicator organisms:
Organisms that respond predictably to various environmental changes and whose presence, absence, and abundance are used as indicators of environmental conditions.
Intermittent stream:
A stream that does not have a continuous flow of water throughout the year.