In the Southern Rocky Mountains, water diversions from headwater streams are a ubiquitous source of streamflow alteration. During the summer and fall of 2005 we analyzed stream reaches above and below 13 diversions on low order streams in Colorado and southern Wyoming that range in baseflow diversion intensity from moderate to near complete. Sites were selected according to strict criteria including an unmodified upstream flow regime, similar character upstream and downstream of diversion, and no potential of metal, nutrient or other chemical water quality impairment. During each visit an extensive set of physical and biological measurements were used to characterize the current stream conditions. We examined upstream vs. downstream flow characteristics using ecohydraulic metrics referenced to process thresholds. We also contrasted fine sediment accumulation, physical habitat variation, and composition of benthic macroinvertebrate assemblages. Below the diversions, we observed significantly more fine sediments in fast flowing habitats and greater areal extents of slow habitats. In general, ecohydraulic metrics provide a more complete representation of diversion effects as compared to measures of % diverted based on total discharge.