BLM REA CYR 2013 Large Streams

Within the study area, small and large stream ecosystems provide important habitat for aquatic insects, fish, and waterbirds. Large streams are those with sufficient depth to allow for deep pool areas, which provide overwintering habitat. Large streams ecosystems support extensive spawning and rearing habitat for numerous fish species in the study area. They also provide important habitat for aquatic invertebrates as well as important transportation and recreational uses for local residents. Large streams are typically less productive than smaller streams due to warmer temperatures in smaller tributaries. Consequently, smaller streams are often preferred summer feeding habitat for many fish species and aquatic insects. Locations of large streams are determined by topography. Because the National Hydrography Dataset was compiled from topographic maps largely developed in the 1950s and 1960s, the distribution of streams contained therein is outdated and does not necessarily reflect current conditions. Therefore, a stream network was calculated using the Tau DEM toolset and the USGS National Elevation Dataset 2 Arc Second Digital Elevation Model within an area of hydrographic influence including and surrounding the Central Yukon study area.