Biennial reporting requires description of the quality of the
Nation's surface waters, evaluation of progress made in
maintaining and restoring water quality, and description of the
extent of remaining problems by using biological data to make
aquatic life use support decisions.

All the groups of organisms living together in the same area,
usually interacting or depending on each other for existence.

The composition of the taxonomic grouping such as fish, algae,
or macroinvertebrates relating primarily to the kinds and number
of organisms in the group.

Regulation of the size of a population by mechanisms that are
themselves controlled by the size of that population (for
example, the availability of resources) and whose effectiveness
increases as population size increases.

Classification designated in water quality standards for each
waterbody or segment that defines the optimal purpose for that
waterbody. Examples are drinking water use and aquatic life use.

Microscopic algae with cell walls made of silicon and have two
separating halves.

A combination of the number of taxa and the relative abundance
of those taxa. A variety of diversity indexes have been
developed to calculate diversity.

The condition of an unimpaired ecosystem as measured by combined
chemical, physical (including physical habitat), and biological
attributes.

The sum of the physical, chemical, and biological environment
occupied by individuals of a particular species, population, or
community, including the food, cover, and space resources needed
for plant and animal livelihood.

Reptiles and amphibians.