Altitudinal Distribution of Brown Trout and Other Fishes in a Headwater Tributary of the South Platte River, Colorado

Upstream distribution of brown trout (Salmo trutta) in the Little South Poudre River drainage stops between the elevations of 2,590 and 2,750 m in five tributaries. As no geomorphic barriers limit distribution, trout distribution may be related to water temperature. Brook trout (Salvelinus fontinalis) is present at higher altitudes in all headwaters. Maximum 5—day water temperature is approximately 13°C at the upper altitudinal distribution of brown trout. Distribution of other species is discussed briefly.