Habitat

A place where the physical and biological elements of ecosystems provide a suitable environment and the food, cover, and space resources needed for plant and animal livelihood.

Headwaters

The uppermost tributaries of a stream or river; often refers to first order streams.

HUC

Hydrologic unit code

Hydrology

The study of the properties, distribution, circulation, and effects of water on the Earth’s surface, soil, and atmosphere.