Discussion
The results of this study indicate the introduction of a channel occlusion and the subsequent hydrologic and geomorphic responses of the riverscape have initiated expansive, positive changes to habitat diversity. Prior research identified that valley plugs can have negative ecosystem implications including various land-use challenges and alterations to both floodplain and sedimentation dynamics (Shields Jr., Knight, & Cooper, 1999; Pierce & King 2008; Fore, Alford, Blackwood, & Blanchard, 2019); however, we observed that in the SRR, the valley plug has facilitated a positive return to near-historic conditions. Accounts of the SRR valley during the early 20th century describe abundant cottonwoods, willows, sedges, and wetlands suggesting the water table was near the surface in much of the valley, similar to what we have seen over the past decade with the evolution of the valley plug (Fortney et al., 2011). Early surveys of the lower SRR also observed a highly sinuous, braided system with multiple low flow channels within the wide active channel (Fortney et al., 2011). Taking these early observations into account, we conclude the conditions surrounding the valley plug are very similar to the historic late 19thand early 20th century condition of the SRR, where the river has shifted from a Stage III degraded riverscape to the anastomosing grassed wetland or Stage 0, of the nine-stage Stream Evolution Model identified by Cluer and Thorne (2014).