Water, sediment and many water quality constituents for rivers are typically derived from upland contributing watersheds as well as from lower-elevation streamside zones and banks. This is particularly evident for the topographically complex landscapes of the interior Pacific Northwest and Great Basin regions, where meltwater frorn high-elevation snowpacks is the primary water source for rivers traversing extensive semiarid lowlands. While river basin management has commonly focused on downstream highorder reaches, natural resource managers are increasingly concerned with small, low-order stream systems and riparian environments in the headwaters of river basins. The need for understanding headwaters hydrology is demonstrated for a rangeland watershed system in which hydrologic regime of headwaters and mid-elevation sectors is intimately linked to streamflow and channel processes in low-elevation, higherorder stream reaches. Comprehensive, successful river and watershed management and simulation model application requires adequately understanding hydrologic and ecosystem characteristics of the source watershed. Water, sediment and many water quality constituents for rivers are typically derived from upland contributing watersheds as well as from lower-elevation streamside zones and banks. This is particularly evident for the topographically complex landscapes of the interior Pacific Northwest and Great Basin regions, where meltwater frorn high-elevation snowpacks is the primary water source for rivers traversing extensive semiarid lowlands. While river basin management has increasingly focused on downstream highorder reaches, natural resource managers are increasingly concerned with small, low-order stream systems and riparian environments in the headwaters of river basins. The need for understanding headwaters hydrology is demonstrated for demonstrated a rangeland watershed system in which hydrologic regime of headwaters and mid-elevation sectors is intimately linked to streamflow and channel processes in low-elevation, higherorder stream reaches. management and simulation model application requires adequately understanding hydrologic and ecosystem characteristics of the source watershed.