Normally hydroelectric dam powerhouses use river flow once before discharging it as turbulent tailwater, ineffective to spin turbines. The present invention uses tapered channels to confine and constrict turbulent tailwater into laminar flow that drives turbines both submersible and floatable utilizing the same water three times concurrently to generate new electricity. Channels originate adjacent to draft tube outlets, constrict in the downstream direction to create narrow necks where turbine/generators benefit from debris free, increased velocity and laminar flows to generate electricity. Hydroelectricity uses zero fuel, creates zero waste and has zero carbon dioxide emissions. Structures are uncomplicated, construction is within project boundaries minimizing environmental impacts and speeding projects coming online. New facilities are protected by existing dam security. Hydroelectricity replaces less dependable renewable energy systems.