Water availability for public supply and irrigation is becoming increasingly important in Colorado and throughout the western U.S.   As demands increase, more water is diverted from natural channels to meet human needs.   Limited ecological research on diversions has focused on the immediate downstream impacts, e.g., showing declines in biological community metrics, but the downstream extent of these impacts has not been assessed.  We have developed a landscape model to assess the spatial extent of hydrologic and macroinvertebrate community alteration below diversion structures in the Fraser River Basin, Colorado. Topological and climatic variables, including contributing basin area, slope, elevation, tributary inflows and precipitation, were incorporated into a GIS flow accumulation model to predict hydrologic recovery downstream of diversion structures. Biological recovery was modeled using empirical relationships between invertebrate community metrics and hydrologic recovery. Field data were collected in July-August, 2006 from nine headwater streams in the Fraser River Basin, with one upstream pre-diversion and several downstream segments sampled for each stream. The rate of downstream hydrologic recovery relative to upstream reference was quantified using discharge, depth, velocity and wetted width.  Benthic invertebrates were collected using a Surber sampler; and taxonomic diversity and functional composition were assessed relative to measured hydrologic recovery.