Tidal Power Alternative to the Severn Barrage

"The main idea, being put forth by the Severn Tidal Fence group, is rather than a full tidal barrier a line of underwater turbines would be built, with spaces between the turbine groups large enough for commercial shipping to pass, as well allowing for the migration of salmon and reducing the risk of flooding upstream by reducing high tide levels upstream from the fence. Mudflat areas used by migratory birds would also be protected."



http://www.treehugger.com/files/2008/07/tidal-power-alternative-to-severn-barrage-touted.php