Restoration of Wallens Bend and Clinch Rivers to Reduce Sediment near Threatened Mussel Shoals

The Clinch River in Northeastern Tennessee supports some of the most diverse, and threatened, mussel shoals in the world. Sediment produced by agriculture, mining, and other anthropogenic activities upstream has endangered the stability of this fragile ecosystem. The Tennessee Stream Mitigation Program, in conjunction with The Nature Conservancy and the Tennessee Wildlife Resource Agency, identified two sites along the Clinch River and a tributary where suitable restoration practices could significantly decrease the amount of erosion and sediment entering the Clinch River system as a consequence of changes upstream of the mussel beds. One site consisted of a 450 foot section of actively eroding bank on the Clinch River. The other site was Wallens Bend, a 2,400 linear foot channelized tributary that is actively incising into the valley floor. This paper discusses the process of identifying potential restoration sites; conducting assessments to identify the existing condition of impacted streams; collecting and analyzing relevant geomorphic and sediment data; developing channel plan, dimension and profile geometry; selecting appropriate vegetation; and developing a construction plan. The project was designed utilizing a combination of empirical.and "analytical" methods. Dimensionless ratios derived from a reference condition provided the foundation on which the design was developed; however, before the design was finalized a series of analytical equations were utilized to assess the sediment transport characteristics of the stream. To minimize the intrusion of equipment into an environmentally sensitive area, the eroding bank along the Clinch River will be reconstructed to correct geometrical deficiencies and supplemented with in-stream structures designed to relieve shear stress along the banks. Wallens Bend will be relocated in the historic valley bottom and the sinuosity will be greatly increased, adding approximately 2,000 linear feet to the channel. The objective of the project is a significant reduction in bank erosion at both sites and an increase of biodiversity within the channel bottom and riparian corridor.