Biological Indicator
An organism, species, assemblage, or community characteristic of a particular habitat, or that it is indicative of a particular set of environmental conditions; also known as a "bioindicator".
Existing Use
A use that was actually attained in a waterbody on or after November 28, 1975, whether or not they are included in the state water quality standards (November 28, 1975 is the date on which U.S. EPA promulgated its first water quality standards regulation in 40CFR Part 131). Existing uses must be maintained and cannot be removed.
Biological Assessment
An evaluation of the biological condition of a waterbody using surveys of the structure and function of a community of resident biota; also known as "bioassessment". It also includes the interdisciplinary process of determining condition and relating that condition to chemical, physical, and biological factors that are measured along with the biological sampling.