This project delivered the first installation and assessment of a ballast water filtration system on an operating commercial bulk cargo vessel (M/V Algonorth) in the Great Lakes. It allowed for the first comparative evaluation of flow-through secondary ballast-water treatment systems using a stationary barge-based experimental platform. Tested treatment systems to prevent ballast-mediated transfers of nonindiginous species underwent substantial redesign in response to initial results. The project team also developed and refined a set of evaluation criteria that are now the ‘the standards to beat’ for ballast water treatment systems in the Great Lakes.