ABSTRACT: A floating surface skimmer is a device that traditionally regulates dewatering in a sediment basin; however, there is also opportunity for their use in post-construction detention basins. Skimmer flow rates are dependent on design and vary across different manufacturers. Theoretical flow rates can lead to errors when estimating dewatering times; therefore, experimental testing is needed to obtain accurate skimmer flow rates. Throughout this study, thirteen floating surface skimmers, eight designed for sediment basins and five designed for post-construction detention basins, were evaluated for their hydraulic performance and to determine their dewatering rates. Testing took place in the skimmer evaluation apparatus at the Auburn University-Stormwater Research Facility. Each skimmer was assessed across several configurations for its hydraulic performance and discharge rates. For each configuration, models were developed using various methods to predict flow rates across depths below 7 ft (2.1 m). Once all flow rate models were developed, two skimmer sizing tools were constructed for the sediment basin skimmers and the post-construction skimmers: an engineer’s calculator and an estimator’s calculator. Overall, the findings of this study indicate that hydraulic performance and associated flow rates vary across different skimmer designs and configurations, ultimately improving selection guidance and enhancing basin functionality.