ABSTRACT
A headwater stream is the origin of most rivers. These streams are small, ‘rst-order streams that have few or no tributary, have incised channels that are eroding, and are found to be associated with seeps or springs (Armantrout 1998). In higher elevations, headwaters are very cold mountain streams with fast ¤ows and relatively straight channels. The channels are incised in mostly coarse inorganic soils, and the ¤owing water is clear. Coldwater streams are usually small ones of stream order 1-3 and greatly affected by conditions of the terrestrial environment, including daily ¤uctuations in ambient temperature. Due to higher elevation, the water temperature is cold and may not exceed an average annual high of 15°C, with a maximum high temperature that does not exceed 20°C. This stream reach also is known as the rhithron: a reach of low temperature, fast and turbulent ¤ow, and substrates of gravel, cobble, or boulder (Armantrout 1998).
