Restoring the River Discontinuum: Looking at the Example of Beaver Dams

River restoration targets are often set according to the River Continuum Concept, in which headwaters are narrow, forested, have coarse substrate, free-flowing water and sediment transport, and connect along a gradient from headwaters to mouth. This investigatory study examines this concept by comparing geometry and substrate of beaver-impounded with non-beaver (NB) headwaters at sixteen river segments in northeastern Connecticut. The beaver-impounded segments were classified in the following categories: valley-wide impoundments (VWI), in-channel dam series (IDS), and downstream of beaver dams (DD). The following width to depth ratios show distinct channels compared with NB: normal IDS (10.8±1.3 vs. 32.9±19.1), bankfull DD (10.2±1.5 vs. 20.0±6.2), and bankfull VWI (52.2±30.2 vs. 20.0±6.2). Additionally, bed substrate distinctions include the following: VWI (100% organic and fines vs. 0%), and IDS and DD (50% and 44% finer than coarse gravel vs. 0%). Given beaver dominance of pre-colonial U.S. river systems, these conditions should be incorporated into restoration targets.