Fish Protection at Cooling Water Intakes and Outfalls: A Concept Using Innovative Electric Fields for 316(b) Protection in Both Fresh and Saltwater Environments

Consistent with recent 316(b) legislation in the USA, cost-effective solutions are needed to minimize fish impingement and entrainment at cooling water intakes in fresh, brackish and full-strength seawater.  We present a concept using rotating electric fields, innovative switching technology and novel electrode designs to preclude fish entry into cooling water structures.  Video evidence from small-scale trials shows how this approach can affect fish behavior.  Recent advances in the understanding of electric fields in various salinities suggest such novel configurations could be deployed to screen relatively large intakes without excessive power demands.  During laboratory trials, technological breakthroughs were achieved in altering behavior and movement of marine species in seawater.  Better known are results we present on successful fish deterrence from hydropower draft tubes and tailraces in freshwater.  Coupled with a Flow Velocity Enhancement System, a hybrid-technology approach could also reduce entrainment of life stages (eggs and larvae) not easily influenced by electric fields.  Behavior of fish and marine mammals in the vicinity of thermal outfalls has received even less attention than impingement / entrainment of fish at cooling water intakes.  Further testing is required to independently evaluate the merits of these innovations in helping facility operators meet new 316(b) requirements.