Nature-like fishways have evolved to pass fish ·with a more full range of swimming abilities as well as to satisfy our ecologic consciousness of restoring stream connectivity using fishways that have a more natural appearance and function. Nature-like fishways take two basic forms. The first is a rock ramp that typically occupies the full channel stream width and carries the full stream flow as a simulation of a natural stream riffle. The other is a roughened channel that conveys a portion of the full stream flow along a separate and longer flow path, usually off the stream edge. It is the hydraulic characteristics of the roughened channel that is of primary interest in this paper. Design of roughened channels is best accomplished by model or prototype physical testing. A more common approach is to use information generated from models, prototypes and constructed fishways in combination with empirical equations to establish the hydraulic characteristics for roughened channel fish ways. The open channel hydraulic empirical relationship in most common use is the Chezy-Manning equation. Critical periods for fish passage are often during low flow conditions where the water depth is significantly below bank full and closer to the height of exposed roughness elements. To better use this relationship as a representation of shallow flow in a small channel with high relative roughness it is important to revisit how the dependent variables of this formula relate to each other, including specifically the Manning "n" representing channel roughness. For this type of application of intentionally creating semi-smooth turbulent (isolated roughness) flow to enable upstream fish passage, the Manning roughness values are much higher than hydraulic engineers are accustomed to using for full channel flow.