LB 16-146 - The effects of re-channelization and chop and drop restoration measures on biofilm and fish abundance in the Little Arnot Watershed, PA

The legacy effects of human disturbance are long lasting in forested watersheds. Common disturbances found in the mid-Atlantic region of the US include historic railroad structures, natural gas extraction infrastructure and timber harvest practices. Restoration techniques that reconnect channel flow and riparian areas and increase large woody debris can provide greater connection of streams to nutrient fluxes, groundwater, and habitat for algae and fish. The goals of our study was to evaluate the influence of stream restoration techniques including chop and drop and large-scale earth movement on habitat, fish abundance and biofilm biomass in the Little Arnot (LiAR) watershed in northwestern Pennsylvania. Our approach include a before-after and control-impact design and 2 years of habitat, fish, and algal measures pre-restoration in LiAR and in the undisturbed control watershed. In conclusion, our findings suggest that the LiAR watershed lacks large wood and is nutrient limited. Habitat quality is poor due to lower abundance of deep pools, low photosynthetic active radiation, and low residence time due to high in-stream water velocity. Wood restoration and rechannelization efforts occurred in late 2021 and early 2022 and we present the emerging results of rechanneling and flooding and increased light availability. Such large wood restoration projects reconnect the stream to its floodplain, decrease downstream flooding, and restore biological functions but take many years of monitoring to best assess success of these mitigation efforts.