Fish ladder Chesapeake Bay Glossary Glossary and Key Word List Definition: A series of ascending pools of running water constructed to allow fish to swim upstream around or over a dam. Fish Ladder EPA EV-Built Environments-Energy Generation Taxonomy Definition 1: Transport structure for safe upstream fish passage around hydropower projects. [DOE Water Power Technologies Office Glossary of Hydropower Terms] Definition 2: Series of ascending pools of running water constructed to allow fish to swim upstream around or over a dam. [Chesapeake Bay Glossary]