Most restoration programmes seek to increase species diversity at degraded locales but few are successful. This failure could be caused by species’ poor dispersal ability, unsuitable environmental conditions (including a lack of essential resources), or by the inability of species to “invade” established communities. However, most research has been unable to separate these different processes. In a recent multi-site experiment in Hughes Ck (Victoria), 26 of 54 common taxa responded to experimental retention of small packs of detritus (leaves, bark) on the stream bed, while 28 showed no response. During the experiment, we captured animals drifting into sites and numbers of winged adults present along stream margins. These data allow us to evaluate whether there were systematic differences in dispersal ability between responding and non-responding taxa. Many species were widespread along the creek and were found in the drift at many locations. Almost all species were found in the drift at some times of the year. However, non-responders inhabiting primarily upstream locations did not drift outside of this zone, whereas upstream-inhabiting responders drifted into downstream areas. For three taxa (two responders and one non-responder) drift was related to benthic densities at manipulation sites but not at control sites, suggesting a strong role for drift dispersal in effecting change. Overall, there were no strong differences in drift rates between responders and non-responders. Likewise, there were no differences in adult numbers trapped at manipulation and control sites. Our results suggest that relatively few species had possible dispersal constraints. Instead, non-responding taxa were more likely blocked either by unsuitable environmental conditions or by an inability to invade established communities. Nonetheless, this study was conducted in a single stream. A new research project is evaluating whether the retention of detritus can improve the diversity of multiple streams degraded by land clearance in Victoria.