The need to accommodate larger reservoir discharge events has prompted the improvement or replacement of existing spillways. One possible spillway modification is the use of an in-reservoir arced labyrinth weir in place of a linear weir. Arced labyrinth weirs can increase crest length (more cycles) and have improved hydraulic efficiency in non-channelized approach flow applications, compared to traditional labyrinth weir applications. In this study, arced labyrinth weir flow characteristics were observed for eleven different laboratory-scale model geometries at the Utah Water Research Laboratory. Rating (Cd vs. HT/P) data and observations were recorded for each configuration, and discharge efficiency was determined. Cycle efficiency, which is representative of the discharge per cycle, was also reported.